"service manual"

Circuit Test Point Impedance

Knowing the source impedance at the point of measurement is critical.

If the source impedance is low, rise time and amplitude measurements are generally no problem.

For example, batteries and power supplies h a v e source impedances of mil- liohms. Signal generators are

25, 50 or 600 ohms. The problem occurs when the source impedance is high.

TTL h a s a source impedance of

-2.5kR so even a t very low frequencies (single shot), measuring fast transition times is difficult a t best.

Basic Probe Considerations

If t h e scope is being used a s a monitoring device, the connection between the signal source and scope select a probelscope combination that has a n Rin that is a t least 100 times greater t h a n t h e source impedance.”

But as frequencies rise, or pulse rise time becomes very fast, scope input capacitance becomes more and more important, forcing use of a n minia- ture passive divider probe to reduce that input capacitance.

And a t the highest frequencies, if both amplitude and rise time are important in high source impedance circuits, an active FET input probe should be used.

If the ultimate in rise time is needed, a

500

divider probe may be used.

However, you must be careful of DC loading. A 50R divider probe with a n input Xc of amplitude

5000 will attenuate the of a signal, or upset the bias of the circuit if you probe the

While probe capacitance distorts pulse shape, the flat portion of t h e pulse top (maximum amplitude) can be used to make a n accurate amplitude measurement since i t contains low frequency information. Conversely, if the pulse width is small compared t o the measurement system rise time, input capacitance can introduce errors since the source cannot fully charge t h e input capacitance during its on time.

This problem becomes worse with increasing source impedance.

3.

When source impedance is unknown, the probe with the highest Zin usually yields the greatest accuracy. However, for frequencies above 10 MHz, high probe capacitance can reduce accuracy more than high probe resistance can help. is usually a direct 50R cable. How- ever, if the scope is being used for signal tracing or circuit analysis, then some type of a n isolating device must be used t o prevent the scope wrong point (e.g., collector of a transistor), or burn up the probe if you draw too much current.

4. If the source voltage is totally unknown, it is wise t o start with a 1 O O : l divider probe t o reduce from loading t h e circuit and a t - tenuating the signal. Today’s modern oscilloscopes use a probe for this isolation.

The frequency of the signal you are measuring and source impedance at the point of measurement influences

A current probe is useful in those certain situations where touching the circuit with any voltage probe a t a l l , even one with t h e smallest capacitance, changes the circuit’s operation. It may be the collector of a transistor where a n inductor and capacitance form a tuned circuit. the possibility of damaging the probe. This will also indicate whether or not there is enough signal available t o capitalize on the relatively low capacitance of a 1OO:l divider probe. However, in real-life situations, you proba- bly don’t have a 1OO:l divider which probe to use. What you want to measure

- is also a weighing factor. In gen- probe. If this is the case use your standard 1 O : l divider probe. eral, there are four types of probes available for common circuit analysis. thumb t o remember is, “To keep resistive loading errors below 1%, important as Rin being high relative t o t h e source impedance.

Probe Rules for Making Rise

Time Measurements

Any voltage probe will load the circuit you are attempting t o measure.

If amplitude measurements at low

If have a a 1. Always try to probe the lowest minimum impedance source. For example

: emi tter-to-base impe- impedance point that contains t h e waveform of interest. For dance of a transistor is generally example: emitter-to-base impe- lower than the collector-to-base dance of a transistor is generally impedance (this implies a bal- lower than the collector-to-base anced input measurement). impedance (this implies a balanced input measurement). frequencies a r e all you a r e in- 2. Select a probe with the highest terested in, then a passive one-to- possible Zin at the frequency of one 1MR non-attenuating probe may be all you need. A good rule-of-

Probe Rules for Making

Amplitude Measurements

interest. When measuring pulse amplitude, capacitance is not as

2. The fastest input system will generally have t h e lowest Rin and Cin. (This rule is limited only by the maximum resistive loading that the source can tolerate.)

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WWW.HPARCHIVE.COM

c

3.

A t high frequencies, the 50R divider probe (500R at lpf) is the best bet for accurate rise time measurements. However, you must be careful of DC loading.

The 500Q input Xc will attenuate t h e amplitude of a signal, or upset the bias of the circuit if you probe the wrong point (e.g., collector of a transistor), or burn up the probe if you draw too much current.

T I m

HOW

1.0

n

. -

.

1 .

bet mee Aavice on

Signal Source Loading and

Probes

Probe Compensation and

Calibrating Your Scope

After you have gone through the rigors of selecting the right probe, you’re ready t o m a k e some measurements.

Let’s begin by making sure your scope is operating properly. You should check its trace alignment astigmatism a n d focus adjustments, and finally, if required, probe compensation.

Trace alignment may be needed if your scope is operated near a strong magnetic field. To make this adjustment, ground the input and adjust the TRACE ALIGNMENT con- the best trace alignment orizontal graticule line. way to adjust astigmatism

3

is with a dot displayed on m. Of course this assumes ir scope has

X-Y display capabilities. If it doesn’t, select the slowest sweep speed possible. This will present a very slow-moving dot which you can use for adjustments.

To adjust astigmatism and focus, set the beam intensity to a low level.

Position the spot to center screen a n d t h e n adjust t h e focus a n d astigmatism controls for the smallest round dot.

How many of you are guilty of pick- ing up a divider probe, connecting it to your scope and t a k i n g measurements without first checking the probe’s compensation?

Application Note 152, titled “Prob- ing In Perspective,” is available free of charge from Hewlett-Packard

(write to the address at the rear of t h i s issue). AN152 describes i n detail all aspects of signal source loading a n d probes. There a r e graphs, formulas, and lots of good information

- be briefly described here.

One of the most common “pilot errors” is using a n un-compensated probe to make measurements. An un-compensated probe will cause errors in the display which will be un- detected Some kind

Of a standard waveform is checked. To be safe, You should always check probe compensation:

adjustments. Overshoot means the compensating capacitance is too large and the high frequencies are not attenuated enough. Undershoot means the capacitance is too small and the high frequencies are attenuated too much.

should be recalibrated using t h e main vertical amplifier gain adjustment (check your scope’s service manual for the proper procedure). day

- to a different input connector

-

To compensate the probe, connect it t o the calibrator squarewave signal, select

DC coupling, and adjust the scope’s controls for a stable display.

Select the lowest VOLTSLDIV setting possible and center the top portion of the squarewave on the screen.

This provides a more precise adjustment method (if your scope is adjusted properly). Adjust the probe until you get a flat-topped square wave with no rounding or overshoot of the signal’s corners. Refer to

Figure 2.

After probe compensation, check the scope’s vertical accuracy against the internal calibrator square wave.

With the vernier in the CAL position, set the VOLTSDIV control to obtain a display that is nearly full scale. The displayed square wave should match the p-p value of the calibrator output. If not, the scope

With the scope checked and t h e

Probe compensated,

Y O U a r e now ready to make some measurements.

Observing Two Signals at the Same Time

There are two techniques oscilloscope manufacturers use to display more than one signal at a time; dual beam and dual trace. The dual beam scope has two independent deflection systems within its CRT; hence two beams a r e displayed s i m u l t a n e - ously. The dual trace scope incorpo- rates electronic switching to alternately connect two input signals to a single deflection system; hence two traces are displayed alternately by a single beam. The switching rate is usually in the 250-500 kHz range.

Most dual beam scopes are used in applications where two events that occur simultaneously would not be displayed correctly on a dual trace scope as i t is switching between signals.


‘Since the greater majority of oscilloscope users have the dual trace mod- els, we will confine this article to those types. Most of the following discussion is confined to the input switching controls on the front panel and how they interact to provide the dual trace capability.

Dual Trace Input Controls

There a r e many various ways to manipulate two signals through two separate vertical input amplifiers and apply them to a single deflection system CRT. Front panel controls allow you t o view the two inputs at what appears to be the same time in either the Alternate or Chop modes.

And you can add or subtract the channels so that you can view the algebraic sum or difference between the two signals, Some oscilloscopes allow you t o switch a channel to the horizontal axis so you can view

Channe1.A on the against Channel B on the

This was discussed i n detail i n

Part

1.

Alternate Mode

In the Alternate mode, the A and

B channels are alternately displayed, one channel per sweep. At fast sweep speeds, the alternate traces will ap- pear t o be displayed a t the same time. However, as the sweep speed is slowed, t h e traces will begin t o flicker showing t h e a l t e r n a t i n g pattern.

Chop Mode

In the Chop mode, both A and B channels are alternately displayed by switching between channels at a fixed high-speed rate (250-500 kHz).

Even a t slow sweep speeds, both channels seem t o be displayed at the same time. Some oscilloscopes have t h e Chop mode connected to t h e sweep control so the scope automatically switches into the Chop mode a t the lower sweep rates.

If your oscilloscope does not have this automatic feature, the general rule is to use the Alternate mode for fast sweep speeds and the Chop mode for slow sweep speeds. On some occa- sions, fast sweeps might require the

Chop mode if the signal rep-rate is low, or even single-shot.

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Algebraic Sum

When both channels A and

B are selected plus

(or added), you’re in the A

B mode. The CRT screen will display the algebraic sum of the two input signals.

One use of the A plus

B mode is the dual channel display of single-shot events. Another use is checking balanced or push-pull type amplifiers.

Balanced signals should have equal amplitude and be 180 degree out of phase. Since the sum of these signals is zero volts, you would expect t o see a straight line. If the signals do not have equal amplitude or are not 180

7

Editor’s Note: The following information about 50-ohm and HF inputs is a small segment edited from one of HP’s application notes. For more information about probes, signal source loading, rise time measurements, and phase measurement rules, send for Probing in

Perspective, Application Note 152.

Use the address on the last page of

‘Bench Briefs’.

In recent years, there has been a lot of discussion over the merits and demerits of these two types of oscilloscope inputs. The key issue in making a comparison is input impedance versus frequency. The

“high impedance” input is only high impedance for frequencies below approximately 1 MHz. Above 1

MHz, the shunt capacitance takes over and there is a fair amount of uncertainty as to what the input im-

1 pedance actually is. The 50-ohm

The 50-Ohm Input Versus

input starts out with low impedance and has essentially a constant input impedance over the oscilloscope vertical amplifier bandwidth, and virtually eliminates the effects of capacitive loading. These input characteristics dictate the applications for which each input is best suited and the choice of probe to do the job.

Problems of “High

Impedance” Scope Inputs

0

Capacitive loading is much higher than with 50-0hm inputs.

0

Input impedance is highly variable with frequency.

0

There is a tendency to have confi- dence that there is no loading because R is high, when in fact capacitive loading is extremely high.

Benefits of “High

Impedance” Scope Inputs

0

Passive probes (refer to Application

Note can be used where high input resistance is required. No need for an active probe unless signal levels are small relative to vertical sensitivity.

0

Does not offer a aood termination for fast 50-ohm signal sources.

Even when a

50-ohm termination is used to shunt the high input resistance, the VSWR caused by the remaining capacitance high.

0

Can tolerate much greater input voltages than a 50-Ohm input.

Benefits of 50-ohm

Oscilloscope Input

0

Can be used with high voltage

0

Minimizes input capacitance and probes. the problems that it causes.

r

degrees out of phase, then the signal

- - you see will be a small sine wave.

Algebraic Difference

When both channels

A

and B are selected and one channel is inverted, you’re in the

A

minus

B mode. The

CRT screen will display the algebraic difference between t h e two input signals.

One use of the

A

minus

B mode is t o measure the voltage across a n ungrounded component without upsetting (or loading the circuit). This is called a balanced o r ungrounded input.

For example, to measure the voltage across the base-emitter junc- tion of a transistor, set both channels to the same volts-per-division, then connect channel A to the base and channel

B to the emitter of the transistor. Connect the ground clips to circuit ground. This allows you t o view the small base-emitter voltage on the CRT without upsetting or grounding the circuit.

Trigger Controls for Dual

Trace Oscilloscopes

The purpose of the trigger circuit is to produce a stable display on the

CRT. This is accomplished by synchronizing the scope’s sweep signal with the signal to be viewed. Several controls allow you to select t h e source, positive or negative mode, and level of the synchronizing trigger signal.

When you’re looking a t just one signal on a single channel scope, triggering is normally simple and straightforward. However, when dealing with complex digital signals, or RF, or two asynchronous signals, you need all the help you can get in the form of additional trigger controls. You need to be able to tell the scope exactly which signal, and even which portion of the signal, to trigger the sweep on.

As

a n example, when you’re looking a t dual trace presentations, you may want to see t h e correct time relationship between two pulses (i.e., how much a pulse on channel

A

leads or trails a pulse on channel

B).

Or, maybe you only want t o compare the shape of two signals, but their time separation makes comparison difficult. The ability to select various trigger functions from t h e front panel enhances the scope’s useabil- ity. Most modern dual trace oscilloscopes feature controls that allow: input channel (shows time relationship) channels (used for pulse shape comparison) delayed sweep) display the trigger signal)

The “High Impedance” Input

0

Presents a better termination for high speed 50-Ohm sources.

Minimizes pulse shape distortion,

VSWR, reflections.

0

When an appropriate probe is added to the 50-Ohm input, the input impedance can be considerably higher than that of a “high impedance” input scope. The source frequency for which this is true de- pends on the particular probe selected. b) Active probes are generally required to increase the input resistance to the 100kR to

10MR area. Active probes are expensive but generally offer a more flexible general probing solution. c) 50-0hm inputs are not compati- ble with high voltage probes.

0

Does not have ac coupling for signal input.

Problems with 50-ohm Input

0

Limited maximum input voltage.

Typically, the maximum voltage which can be applied directly is less than +1OV.

Sum ma ry

Requires a probe to increase the input resistance: a) Passive probes can be used to increase the input resistance to

5kQ if 1 OOX division ratios can be used.

To summarize, the 50-ohm input offers superior measurement capability in many situations. However, it cannot be considered to be a general purpose solution because a probe is required to increase the input resistance, and ac coupling is not available without an active probe.

The high impedance oscilloscope input is more general purpose than the 50-ohm input. However, it is generally not as capable for making accurate high speed pulse measurements, phase shift measurements, and high frequency amplitude measurements, even when a probe has been carefully selected.

Most oscilloscope manufacturers offer selectable high impedance and 50-ohm inputs in the same mainframe or plug-in vertical amplifier. The choice of both inputs plus the various probes offered allow the versatility required to make most waveform measurements.


______I_

~-

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-

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Composite Triggering

Trigger Holdoff

Selectable Triggering

Composite triggering is the only way

Trigger Holdoff is a variable control

Selectable triggering is a conven- to show two asynchronous signals. I t works like this. In the Alternate used in conjunction with the Trigger

Level control. Trigger Holdoff ience feature. I t allows you to look at t h e display a n d t h e n select t h e mode, Channel A sweeps once, then increases the time between sweeps proper trigger source a t the push of a

Channel B, etc. The trigger selection and helps stabilize the display when button. Selectable triggering allows you t o trigger t h e display from controls cause t h e sweep to be triggered by the displayed signal; triggering off complex digital signals. On scopes without this control either one of the input channels. you would use the Sweep Vernier therefore when Channel A is being displayed, it is the trigger source control as a holdoff, but then your

A typical set-up might be a signal and when Channel

B is being dis- sweep is no longer calibrated. pulse into Channel A and its trigger played, it is the trigger source. pulse into Channel B. The correct

Trigger View

time relationship between the pulses

A typical set-up might be two asyn- Some oscilloscopes have a feature i s obtained when t h e sweep i s chronous pulses with nanosecond called trigger view. Basically triggered by Channel B’s signal in rise tiwes but separated in time by allows you to simultaneously display the Alternate mode with Internal microseconds. You don’t care about the external trigger signal on the trigger selected. Figure 3 shows how the time relationship between the

CRT in addition to the input signals. the time relationship between the two signals but want to compare the This can be quite valuable in verify- two signals changes when the trig- pulse shapes. If a fast sweep is used, ing the time relationship of the triggering is changed from Channel B to only one of the pulses can be dis- ger signal t o t h e displayed

Channel A. played at a time.

1 compared by selecting Composite triggering in the Alternate mode. i t

Figure

4

shows how the time relationship between the two pulses is lost when composite triggering is used.

,

.. .

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Delayed Triggering

Figure 3. Trigger example showing time relationship between signal connected to CHAN

B.

View ‘ A shows the display (sweep) being triggered on the positive-going edge of CHAN B trigger. View ‘6’ shows the display being triggered on the positive-going edge of CHAN A signal.

‘ A

=

Internal trigger

Alternate display

Trigger on CHAN B (correct)

Positive slope

’ B

=

Internal trigger

Alternate display

Trigger on CHAN A (incorrect)

Positive slope

Delayed triggering is directly tied to

Delayed Sweep. Delayed Sweep allows easy location and expansion of a small portion of the display, permitting detailed analysis of that portion of the waveform. Delayed

Sweep can be triggered after a pro- grammed delay, eliminating any waveform jitter from the expanded display.

How the sweep is triggered in the

Delayed Sweep mode will be described in the Delayed Sweep portion of this article. Trying to explain it now may cause some confusion.

Figure 4. Composite trigger example showing how to compare two asynchronous signals connected to CHAN

A and CHAN B.

“ A ’

Internal trigger (correct

AIternate display time

Trigger on A or B relationship)

“B”

=

Internal trigger (incorrect

Alternate display time rela-

Composite Trigger tionship)

In Alternate mode and Composite

Trigger, each signal is its own trigger source. Effective for signal shape comparison.


I

r

c'

waveforms. In Trigger View, the point where the center horizontal graticule line a n d t h e trigger waveform intersect is the trigger point. By varying the Trigger Level and Slope controls, you can select any point on the positive or negative edge of t h e displayed trigger waveform t o trigger the sweep circuit, and measure how it affects the input signals.

- -

.-..

T .

..

-

1 1

Banawiatn Limit Control

The bandwidth of some scopes can be reduced to minimize interference in high noise areas such as airports and broadcast stations. On t h e H P

1740A, the limiter effectively re-

rlllrDc

UUI.2" thn

Y l l U

crnno'c hanrlur;rlth

U U I l Y frnm

100 MHz t o 20 MHz.

For example, suppose you are pick- ing up interference from 27 MHz citizens band equipment. If the test signal is less than 20 MHz, use the

Bandwidth Limit control to reduce the high frequency interference.

Delaved SweeD

Thi mo m b- ably one

or

tne least unaerstood capabilities of a modern oscilloscope.

I n basic terms,

the scope with delayed sweep simply has two time bases

-

main and delayed.

The controls for the two time bases may be labeled and arranged in various ways a n d have various capabilities, depending on the rnan- ufacturer, but their purpose is basically t h e same

- expand a selected portion of the displayed signal. To accomplish this, each time base has its own complete set of sweep and trigger controls.

In simple terms, delayed sweep functions as follows. The signal is first triggered by the main sweep a t the speed set by the TIMEDIV dial. The delayed sweep speed control is then set to a faster sweep speed than the main sweep (the delayed sweep is triggered after t h e main). This causes a small part of the main- sweep trace to become intensified or brightened, depending on the setting of the delayed sweep speed control.

The slower the setting, the larger the intensified portion becomes. This intensified marker can be moved along the signal by rotating the

DELAY control. Then, if we switch the mode to Delayed Sweep, AUTO mode, only the intensified portion will be displayed over t h e full screen. In other words, we have

r

nagnified a portion of the trace.

._r

. .

..

.

. pened if we consider the signal being displayed by two time bases; first the main sweep followed by the delayed, faster sweep (the intensified portion).

What we have done is to set up a delay time from the start of the trace t o the beginning of the intensified portion of the trace. When the delayed sweep is automatically triggered, this time is equal t o the distance i n centimeters from the start of the trace to the intensified trace, multiplied by the sweep time per centimeter (i.e., it's calibrated).

The product is the delay time. When we switch to Delayed Sweep (push the DLY'D button on the HP 1740A), we start the main time base with an input trigger, but we do not use it to display the signal. Instead, we use it as a clock that simply marks time until the delay period is over. Then the delayed time base sweeps, dis- playing the signal. Figure 5 shows how the delay system works in the

AUTO mode.

There are two ways to cause the delayed sweep to be initiated after the delay time. The first way (discussed above), is called the AUTO mode.

The delayed sweep automatically starts a t the end of the delay period with no trigger signal or other external command needed. In the

sweep sawtooth waveforms. Delay time (twtl) is set by DELAY control,

DLY'D TIME/DIV control. tl-12 is the intensified part of the waveform.

When SWEEP AFTER DELAY control is set to AUTO, sweep is triggered automatically at t l .

other mode, the delayed sweep is armed at the end of the delay period and requires a trigger signal (either internal or external) to start the delayed sweep. Since there is no way t o know when the trigger signal will occur, t h e delay t i m e i s uncalibrated.

Each of these methods has its own advantages. In the AUTO mode, all of the accumulative rate jitter that has occurred since the start of the delay time is displayed on the delayed sweep.

If, on the other hand, rate jitter is not desired in the display and a clear picture is needed, then the armed mode should be used.

In this mode the delayed sweep is retriggered after the delay time. A new time reference is established, eliminating all of the jitter that has occurred previously, providing a clear picture for accurate measurements on the expanded pulse.

How To Use Delayed Sweep

The delay controls on your oscilloscope usually will be highlighted by color or surrounded by lines on the front panel. The HP 1740A sweep and delay controls are easy to find


Then move the DLY’D TIMEDIV control out of its OFF position. When this is done, a portion of t h e waveform should become i n t e n - sified. This intensified marker is used t o locate the portion of the waveform to be expanded. Adjust the

Delayed Sweep Speed control so the marker is a little wider than the pulse t o be measured. Set t h e

SWEEP AFTER DELAY control to the AUTO position.

Figure 6. Pulse width measurement using the delayed sweep controls.

DLY’D TlMElDlV dial

Full scale accuracy

7

x 50pS

=

350pS

=

Sops

=

3%

(of

SOOps)

0.03

x 500ps

=

1Sps

accuracy pulse width

=

3 5 0 p

rt_

15ps

because of t h e d a r k grey background. But no matter which scope you have, look for the word DELAY in the control nomenclature.

Suppose you want to measure the width and rise time of the 5th pulse in a pulse train. If you try and expand the signal with the main sweep control, the pulse moves off screen.

You could use the horizontal magnifier to expand the sweep time and perform the measurements as described in Part l. However, you want more accuracy t h a n t h a t method allows. The point about accuracy to remember i s t h a t time interval measurements are LEAST accurate using the X10 magnifier, BETTER using direct delayed sweep, and

BEST using differential delayed sweep.

Next move the intensified marker along t h e waveform with t h e

DELAY control until it is over the pulse to be measured. Use the horizontal position control t o center the intensified pulse. Expand the intensified portion to the full width of the screen by selecting Delayed Sweep

(on the HP

1740 push the DLY’D pushbutton). Slightly re-just t h e

DELAY control to make the leading edge 50% point intersect a convenient vertical graticule line. Count the number of divisions between the

50%

points and multiply that times the Delayed Sweep Speed control setting. Figure 6 shows an example pulse width measurement using the delay controls.

Differential Delayed Sweep

A more accurate time interval measurement can usually be made using t h e Differential Delayed

Sweep method. To make a differential measurement, select Main Sweep and adjust the TIMEDIV control to expand the sweep

speed

to make the pulse you want to measure as wide as possible. If the time interval of the pulse is greater than one-half division on the screen, the differential method will be more accurate than the delayed sweep method.

NOTE

If you don’t have some type of pulse generator for the following experiments, try using the amplitude calibator output on your scope.

The first step in measuring pulse width and rise time is to adjust the vertical controls so that pulse height is six divisions (Le., enough height t o easily see the

50%

point).

Switch the Delayed TIMEDIV control out of its OFF position. When this is done you should see the intensified marker as in the previous measurement. Adjust the Delayed

TIMEDIV control so the marker is a little wider t h a n the pulse to be measured.


Next move the intensified marker alQng t h e waveform with t h e

DELAY control until it is over the pulse to be measured. Expand the intensified portion t o the full width of the screen by selecting Delayed

Sweep (on the HP 1740A push the

DLY’D button).

/7

Adjust the DELAY control to position the

50%

amplitude point of the leading edge over the center vertical graticule line. Read and record the

DELAY dial setting. Note that some oscilloscopes use an LED readout for this purpose.

Re-adjust the DELAY control to position t h e t r a i l i n g edge

50%

amplitude point over the center vertical graticule line. Read and record the DELAY dial setting. The pulse width is the difference between the two readings times the main sweep

TIMEDIV setting. Figure 7 shows a n example pulse width measurement using the differential method.

A Note on Time Interval

Measurement Accuracy

The absolute accuracy of the

Differential Delayed Sweep method relies on the princi- pal that the time interval of the pulse to be measured is greater than lcm of the main sweep. In this case the accuracy is X% of the reading

+

Y% of full scale. The

Y%

of

full scale will totally mask out the accuracy of the measurement. For the

HP

1740A, the accuracy is

-+

0.5%

of the reading

20.1%

of full scale. Therefore, the accuracy of a lOcm (full scale) measurement is

2

0.6%.

However, as the reading is reduced to smaller and smaller parts of the main display, the accuracy de- creases

(+

error increases).

At one division of main sweep the error is

2

1.5%

at 112 division of main sweep the error is now about equal to that of the direct-from-

CRT measurement.

’1

1

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pulse’s rise time or even its width.

The scopes we have been discussing usually provide a feature to elimi- n a t e this unwanted j i t t e r called Delayed Trigger.

Delayed Trigger controls are much the same as those that control the main sweep. There is a pushbutton that selects either AUTO or TRIG mode (which is similiar to t h e

AUTO-NORM mode). When in the

TRIG mode, other controls are en- abled that allow you to select the delayed sweep to be triggered “in- ternally” or “externally,” divide the external trigger amplitude by 10,

AC or DC couple the trigger signal, and adjust the Slope and Trigger

Level to start the delayed sweep a t any point on the waveform. a t the faster delayed-sweep rate. The transition point between sweeps is positioned with the DELAY control after the MIXED button is pressed.

Mixed Sweep is convenient for “peel- ing oft’’ pulses one by one from a long t r a i n and examining t h e m individually.

Using the Dual Trace Scope to Read Propagation Delay

Propagation delay in reference to digital circuits is the amount of time it takes for a change a t the circuit’s input t o be noticed at its output. For example, when the input voltage to an AND gate changes from a low to a high, the output will respond a t some later finite time. You can use your scope t o quickly and easily measure t h i s time a n d check i t against the device’s specification.

Let’s use the input signal as the trigger source to see how the delayed sweep is triggered. Refer t o

Figure 8.

Use

DELAY control to center trailing edge of pulse over center horizontal graticule.

Figure 7. Pulse width measurement using the differential delayed sweep method. DELAY control is used to center the leading edge and then trailing edge of pulse over center horizontal graticule. Pulse width is difference between the two readings times the main sweep TIME/DIV dial setting.

TIME/DIV dial

=

0.2ms

DELAY dial reading

=

7.46

-5.70

1.76

1.76 x 0.2ms

=

352ps

Accuracy is 20.5% for the DELAY dial and -t0.1% of full scale

0.005 x 352

0.001 x 2ms

=

176ps (dial)

=

2ps(fuII scale) pulse width 3 5 2 ~ s 4 p ~

How To Use The Delayed Trigger

Method To Eliminate Waveform

Jitter

Often, when you expand a signal, waveform jitter becomes more pro- nounced. This jitter makes it difficult to accurately measure the

Each input pulse produces a trigger pulse. The main sweep is started by the first trigger pulse. The second trigger pulse doesn’t do anything because it’s blanked by the delay time set by the DELAY control. The delayed sweep is “ a r m e d at t l when the delay time ends. The next trigger pulse to arrive after the delay time ends starts the delayed sweep sawtooth which deflects the electron beam across the CRT. Since there is no way to know when the trigger signal will occur, the delay time is uncalibrated.

In effect, you have eliminated all interference by triggering the sweep on only that portion of the waveform you have selected to examine.

Mixed Sweep Mode

There is another mode of delayed- sweep operation found on some oscilloscopes, called mixed sweep. In this mode the main sweep is displayed on the screen for the amount of delayed time desired. Then t h e sweep increases in speed part way across the screen and finishes up the trace

I t would be difficult to specify a test circuit and all the clips and probes required to complete such a test. By now you should already have your scope set-up, probes compensated, and enough background information to complete your own experiment.

The necessary scope control settings are as follows:

Ma,n

swPep

Delayed sweep

1

1

I

I i*

Tilggrrs

blanked

durinq

I delay lime

1

‘ 0

1

I

I

I

I

‘1

:

I

I

‘ 2

Figure 8. Delayed sweep delayed trigger example. The main sweep is started by the first trigger pulse at to.

The second trigger pulse “arms” the delayed sweep at t l . The next trigger pulse to arrive after the delay time ends starts the delayed sweep sawtooth at tq. The time between t l and t2 is unknown which makes the delayed sweep uncalibrated.


ohm passive probe is useful in high impedance circuits where maximum rise time accuracy is necessary)

AC

CHAN A

CHAN B

AUTO mode so signals are centered and approximately six divisions high pulses look like those used for making rise time measurements

You should see the leading edges of two pulses separated by a measura- ble distance. Measure the propagation delay at the 50% points (center horizontal graticule line) by count- ing the number of divisions between the two pulses and multiplying that times the setting of the sweep speed control. If you measure two divisions and the TIMEDIV dial is set at 5 ns, the propagation delay is 10 ns. For greater resolution, use the x10 magnifier or delayed sweep.

Using the Dual Trace Scope to Measure Phase

Difference

I n t h e previous issue of Bench

Briefs, Part 1 discussed how to make crude phase measurements using

Lissajous patterns. Earlier in this article, it was shown how you can use the Algebraic Sum of two channels to make sure the outputs of a push-pull amplifier are 180 degrees out of phase

- measurement.

A more accurate method of phase measurement uses the time-delay principle. This is the same type measurement discussed previously under the heading, “How To Meas- ure Propagation Delay.” I t involves looking at two signals simultaneously and observing any phase difference between the two.

One example of using the time-delay method to m a k e accurate phase measurements is checking the output of a stereo tape player. The head alignment, or azimuth, must be pre- cisely set for best high frequency and zero phase response. The necessary scope control settings are as follows:

AC output to CHAN A output to CHAN B quency test signal)

AUTO mode t o

If the recorder’s head is adjusted properly, both signals should lie on top of one another which indicates they are in phase, Varying the head azimuth will shift the phase of the signals which you can read directly off the display (remember that one division equals nifier. Now each division represents

4.5

degrees.

4 5

degrees). For greater resolution use the x10 mag-

This concludes the Basic Oscillo- scope articles. For more information on specific oscilloscope applications,

Hewlett-Packard offfers many free application notes. Several examples are: AN152 tive, AN223 urements in Digital Systems,

AN185-2

Matching and Length Measurings

Using Dual-Delayed Sweep, and

AN262

Errors from Oscilloscope Meas- urements. Many HP engineers and customers have collaborated on these notes t o pass their applications research and experience on t o you.

Some notes are tutorial in nature, while others describe very specific

“how to” procedures. All HP application notes are designed to help you obtain maximum use from your

Hewlett-Packard equipment. Please contact your local HP office for more information. nals are centered and approximately six divisions high so that one cycle covers exactly eight horizontal divisions. Eight divisions divided into 360 degrees equals 45 degrees-per-division.

Editor’s Note: Parts 1 and

2

of this oscilloscope article have been

com-

bined into a training note and pub- lished under H P Part No. 5953-3873.

For free reprints, please write to

Steve Sinn, M A R C O M Manager,

Hewlett-Packard, PO

Box

2197,

Colorado Springs,

CO

80901.

7

4

,

.

?

Hewlett-Packard continually offers training to customers on a worldwide basis to help keep service skills current with HP’s extensive product line. Seminars are pro- vided throughout Europe and the United

8640 AM/FM Signal Generators

8660 Synthesized Signal Generators

435/436 Power Meters or

8672A Synthesized Signal Generator

August 25-29, Palo Alto, Ca

States in a n effort to bring our training facilities closer to your area. For registration information please refer to page 20 of

Bench

Briefs a n d contact your local

Hewlett-Packard Office.

COURSE CONTENT

LECTURE

I. Introduction

11. Features and Model Options

111.

Front Panel Features

A. Video Tape

B. Demonstration

IV. Theory

A. Block Diagram

B. Assembly Locations

C. Schematic

LAB

I.

Adjustments

11. Performance Tests

111. Troubleshooting

OPTIONAL

Last day you can choose Lectureflab between power meters or synthesized signal generators.

PREREQUISITES

Basic knowledge of digital logic circuits and general knowledge of electronics including operational amplifiers and phase lock circuits.

< i

141T, 8552A/B, 8553B,

8554B, 8555A

Spectrum Analyzers

August 6-8, Santa Rosa, Ca

Seminar No. 4544-6932

COURSE CONTENT

LECTURE

I.

11.

Block Diagram Related to Front Panel Controls

Overall Block Diagram and System Description

111. Detailed Block Diagram

1

IV. Circuit Descriptions

A. Input Circuits

B.

First, Second and Third Mixers and IF Stages

C. YIG Drive Circuits

D. 50 MHz Amplifier

E. Marker Generator

F.

Phase-Lock Circuits

V. Troubleshooting Techniques (“Bugged”

Instruments)

VI.

Repair Cautions and Mechanical Tuning

Adjustments

LAB

I.

Front Panel Familiarization

11. Change First Mixer

111. Set Up YIG Frequency

IV. Normal Calibration

8566N8568A

Programmable Spectrum Analyzers

Same Seminar Given

3

Times,

Contact Factory Coordinator

For Preferred Week

Sept. 15-19

Sept. 22-26

Sept. 29

-

3

Santa Rosa, Ca

Seminar No. 4544-6934

COURSE CONTENT

LECTURE

I.

RF Sections

A. Block Diagram

B.

Pilot Third Local Oscillator

C .

Derivation of Center Frequency Equation

D.

System Sweep Control

E. RF Module

F. Synthesized LO

G. YTO Loop

11. IF Sections

A.

A3 Digital Storage

B. Signature Analysis

C .

Diagnostic Functions

D. System Troubleshooting

c

I.

Front Panel Familiarization

11. -

. .

q . . 1

111. Normal Lalibration

PREREQUISITES

Previous experience servicing spectrum analyzers, digital circuit knowledge, and some knowledge of micro- processors is helpful. Knowledge of bus structure as used in computers and digital equipment is very important in understanding the H P 8566A and 8568A Spectrum

Analyzers.

r

I

DTS-70 PCB Test System

Service Seminar

Loveland, Colorado

COURSE CONTENT

LECTURE AND LAB

[.

Product Familiarization

[I.

RTE Review

A. FMGR

B. RTE-IV B

C. Editor

D. Disc Organization

E. Utilities

[II. Testaidmastrace Overview

[V. System Troubleshooting

A.

System Functional Test Assy.

B. DTS-70 Hardware

1. Digital Test Unit

2.

Driver/Comparator Cards

3. Power Supplies

4.

HP-IB Subsystem

C. Preventative Maintenance

D. System Functional Test

V.

VI.

VII.

RTE

InstallationDteconfiguration

91075C DTS-70 Software Installation

Program Development

VI11

[.

Virtual Memory System Overview

IX.

System Transfer Files

X.

XI.

XI1

,

Board Testing With Standard Files

HardwareJSoftware Integration

Warranty/Support Policies

PREREQUISITES

Some formal HP-1000 Disc-Based RTE course, prefera- bly RTE-IV or RTE-IV B.

f-

3060 Circuit Test System

Service Seminar

August 18-29

October 20-31

Loveland, Colorado

COURSE CONTENT

LECTURE AND LAB

I.

Introduction to Course, System, and BTL.

11. Review of HPL and HP-IB

111. System Control Panel

IV. System Multiplexing

V. 3496A Scanner Troubleshooting

VI. 11353Al11453A Diagnostic Fixtures

VII. 34196A Scanner Power Supply

VIII. 11253A System Power Module

IX. Analog In-Circuit Testing

X. Transfer Testing

XI. 3253A Analog Stimulus/Response Unit Theory of

Operation

7

XII. 3253A Analog Stimulus/Response Unit

Calibration

XIII. 3253A Analog StimuluslResponse Unit

Hardware Familiarization

XIV. 3253A Analog StirnuluslResponse Unit

Troubleshooting Exercises

XV. 3453A Digital StimuluslResponse Unit

Programming

XVI. Static Pattern Testing

XVII D.U.T. Power Supplies

XVIII. D.U.T. Clock

XIX. 3453A Digital Stimulus/Response Unit

Troubleshooting

XX. System Troubleshooting

PREREQUISITES

1.

9825A HPL Programming

2. 9885M HPL Programming

3. Knowledge of HP Logic Symbology

4. Knowledge of

Operational Amplifier Circuits

5. Knowledge of Basic Logic Circuits

All the above prerequisites are mandatory.


‘

Attention 5036A

Microprocessor

Lab Owners

There has been a lot

of

inquiries about replacing the 5036A Micro- processor Lab’s “suitcase”. Due to a n oversight, the suitcase part number was not included i n t h e Service

The

HP part number is 1540-0537.

If part of the case becomes damaged and must be replaced, it is necessary to purchase the complete case. This i s because t h e cases come pre- matched, lid-to-bottom, from t h e supplier.

In general, these tools are used as test sets by field-servicemen on-site, as tools on the production line, and especially around PC board testers as accessories.

I t takes circuit knowledge and skill to use simple tools like the IC Trou- bleshooters in digital troubleshooting. This applications note should enhance your ability to use probes, pulsers, current tracers, logic clips

-3 and logic comparators.

In order to mount the power supply assembly, it is necessary for the cus- tomer to drill the mounting holes in t h e new case t o ensure proper alignment. All mounting hardware not included with the new case should be obtained from the replaced case. In case of loss, the hardware part numbers are:

Number 05036-40002.

Number 05036-00003.

H P Part

The proper procedure for replacing the lab in the suitcase is:

1. Open the case and fold the circuit board until access is gained t o the two screws holding the plastic insert case to the power supply.

2. Remove these two screws completely and retain for replacement.

3. Loosen the four screws a t the ends of the case several turns.

4. Lift the plastic insert case free of the main case. Do not unsolder t h e PC board from the power supply.

For more information order service note 5036A-1 using the form at the rear of Bench Brie/%.

Another Puzzle

There is a small repair center that has five different nationality tech- nicians who sit a t five differently colored benches and work on five different products. Each technician uses a different method of transportation to get to work and prefers a different choice of drink.

1. The Englishman works a t the red bench.

2.

The Spaniard walks to work.

3. Coffee is drunk a t the green bench.

4. The German drinks tea.

5.

The green bench is immediately to the right of the black bench.

6. The technician that works on signal generators rides a bicycle t o work.

7. DVMs are worked on at the yel- low bench.

8. Milk is drunk a t the middle bench.

9.

The Frenchman works a t the first bench.

10. The technician who works on scopes sits next to the technician that drives a car to work.

11. DVM’s are worked on at the bench next to the bench where the technician rides a motorcy- cle to work.

12. The counter technician drinks orange juice.

13. The Japanese works on distortion analyzers.

14. The Frenchman sits a t t h e bench next to the blue bench.

Answer these questions:

Who drinks water?

Who rides the bus to

w d k ?

a


3747AlB SELECTIVE LEVEL

MEASURING SET

3747NB-4A. 3747A serials 1930U and below; 37478 serials 19241) and below. Preferred replacement of

ROM4 on A109 CPU Memory Assembly.

3747NB-13. 3747A serials 1950U and below; 37478 serials 192411 and below. Modification to prevent erroneous level measurements using A301 notch filter.

3747NB-14. 3747A all serials. Instructions on how to select

C C l n plans during remote HP-I8 operation.

3747NB-15. 3747A serials 1950U and below; 37478 serials 1924U and below. Modification to prevent erroneous level measurements using 2.5kHz filter.

3747NB-16. 3747A serials 1924U-00140 and below;

37478 serials 192411-001 15 and below. Improve- ment in the suppression of line radiated RFI.

3763A ERROR DETECTOR

3763A-3. Serials 1947U-00326 and below. Modifica- tion to improve reliability of power supply switching transistor.

3771NB DATA LINE ANALYZER

3771NB-9A. All serials. Table of board link variations with 3771A. 37718 and options.

3 7 7 l N B DATA LINE ANALYZER

OPTION 005 HP-IB

3771A/B-10. 3771A serials below 1937U-00160;

3771 B serials below 193711-001 23. Modification to prevent possible remote mode malfunction.

3771NB-11. All serials. Retrofitting instructions for

Option 002 (Loop Holding).

3771NB-12. 3771A serials 193711-00165 and below;

3771 B serials 1937U-00123 and below. Preferred replacement of assembly A3 t Input Transformer

T1.

377lNB-13. 3771A serials 200211-00175 and below;

1

-

37718 serials 1937U-00123 and below. Modifica- tion to prevent loss of DC loop holding path when

MEAWSPEAK switch is set from SPEAK to MEAS.

377lNB-14. All serials. Preferred replacement of re- sisters A3R6 and A3R7.

3771NB-15. 3771A serials 2002U-00180 and below;

3771 B serials 1937U-00123 and below. Modifica- tion to prevent possible loss of the 2040Hz transmission frequency when frequency shift is selected in the 3771A.

3771 AJB-1 6. 3771 A serials 2002U-00175 and below;

3771 B serials 1937U-00128 and below. Installation of troubleshooting aid for HP-16 section.

3777A CHANNEL SELECTOR

3777A-1. Serials 173OU-00215 and below. Preferred replacement relays.

3777A-2. Serials 173011-00215 and below. Preferred replacement for assemblies A4, A5, A6, A7, and A8.

3779AlB PRIMARY

MULTIPLEX ANALYZER

3779A-14. Serials 193611-00185 and below. Preferred replacement for assemblies A1

,

A8, A9. A31, A35,

-3

and A37.

3779A-15. Serials 191 9U-00175 and below. Modifica- tion to prevent intermittent single channel interface operation while running

A-D measurements.

3779A-16. Serials 1919U-00180 and below. Modifica- tion to prevent intermittent GvL measurements when running wet line systems.

3779A-17. Serials 193611-00180 and below. Modifica- tion to prevent erroneous result during low level gain measurements.

37796-14. Serials 1941 U-00220 and below. Preferred replacement for assemblies A l , AB, A9, A31, A35, and A37.

37796-15. Serials 193311-00206 and below. Modifica- tion to prevent intermittent single channel interface operation while running A-D measurements.

37796-16. Serials 1941 U-00216 and below. Modifica- tions to prevent intermittent GvL measurements when running wet line systems.

37796-17. Serials 1941 U-00225 and below. Modifica- tions to prevent erroneous result during low level gain measurements.

3790A lF/BB RECEIVER

3790A-9. All serials. Preferred replacement for NPN transistor (1 654-0071).

3791A/B lF/BB RECEIVER

3791A-6. All serials. Preferred replacement for NPN transistor (1854-0071

).

3791 6-1. All serials. Preferred replacement for NPN transistor (1 854-0071).

3792A IFIBB RECEIVER


3793AlB IFIBB RECEIVER


37936-1. All serials. Preferred replacement for NPN transistor (1 854-0071).

3964Al3968A INSTRUMENTATION

TAPE RECORDER

3964A-17/3968A-17. Serials 2009 and above. New type recommended instrumentation recording tape.

3964A-18/3968A-18. All serials. New adjustment procedure for FM data assemblies, 3464A part number

03964-60506, and 3968A part number 03964-

60508.

4140A pA METER1

DC VOLTAGE SOURCE

41 40A-1. Serials 191 7J00195 and below. Modification to improve stability in signature analysis.

4140A-2. All serials. Description of performance test kit for 4140A.

4262A LCR METER

4262A-9. Serials 1739J01650 and below. Description of possible "fail" annunciation display at beginning of self test operation.

4282A DIGITAL HIGH

CAPACITANCE METER

4282A-6. All serials. Revised AGC adjustrqent procedure.

4328A MILLIOHMMETER

4328A-7. Serials 121 0 and below. Preferred replacement probes.

4943A TRANSMISSION IMPAIRMENT

MEASURING SET

4943A-2. All serials. Instructions for field installation of

Option 010 (HP-16).

4943A-3. Serials 1731 A00205 and below. Modification to correct A8 modem duty cycle.

4943A-4. Seials 1731 A00254 and below. Modification to improve performance.

4943A-7. Serials 1731 A00240 and below. Modification to improve performance and prevent intermittent level dropout.

=A TRAhlsknSSK)N WAIRMENT

MEASURING SET

4944A-1A. All serials. Instructions for field installation of Option 010 (HP-18).

4944A-2. Serials 1737A00476 and below. Modification to improve performance.

4944A-3. Serials 1737A00328 and below. Modification to correct A8 modem duty cycle.

4944A-6. Serials 1737A00481 and below. Modification to improve performance and prevent intermittent level dropout.

5036A MICROPROCESSOR LAB

5036A-1. All serials. Suitcase replacement part number is 1540-0537.

5045A DIGITAL IC TESTER

5045A-20. New operational verification test using R- pack checks. Supersedes 5045A-8.

5315AlB UNIVERSAL COUNTER

5315NB-1. Serials 1832A, 1624A, and 1812A. MRC chip replacement procedure.

53268153278 TIMER/COUNTER/DVM

53268/53278-10. All serials. Revised in-cabinet per. formance check.

5328A UNIVERSAL COUNTER

5328A-256. Serials 1952A13473 or 1948U02430 and below. Modification to improve DAC settling time for

Option 041.

5328A-26. Serials 1936A13173 or 1948UO2280 and below. Modification to correct interface problem with the HP 9845A controller.

5340A MICROWAVE FREQUENCY

COUNTER

5340A-9A. Serials 1644A04200 and below. Line fuse change for improved transformer protection.

5340A-13A. Serials 1936A and below. Recommended replacement for A1 7 direct count amplifier.

534544 COUNTER

5345A-10A. Serials 1708 and below. Resistor changes on A4 input trigger assembly (05345-60004) to improve performance.

5359A TIME SYNTHESIZER

5359A-1. All serials. Operation verification procedure for the A17 Output Reference board.

5959A-2. All serials. Operation verification procedure for the A18 output assembly.

5363AlB TIME INTERVAL PROBE

5363A-5. All serials. New signature analysis procedures for the 5363A time interval probes.

53638-1A. Serials 1832A and below. Modification to prevent trigger output oscillations.

53636-4. All serials. Simple troubleshooting procedure for 53638 calibration errors.

53636-5. All serials. New signature analysis procedures for the 53638 time interval probes.

5370A TIME INTERVAL COUNTER

5370A-6. Modification to add top cover vinyl and cork strip to help prevent board displacement.

5420A DIGITAL SIGNAL ANALYZER

5420A-21A. Listing of previous service notes that are important to the reliability of the 5420A.

5420A-22. Modification to improve the 5441A display transport assembly.

5420A-23. Recommended replacements for the

544tA. Mother Board (05441-60101), FDB Board

(05441-60241), and Servo Board (05441-60271).

5420A-24. Modifications to improve performance.

5427A DIGITAL SIGNAL ANALYZER

5427A-02. Model 5478C A-D Converter. Serials

1928A00230 and below. Modification to improve

5427A self check results.

55OOCl5501 Al5505A LASER HEAD

sup- plement to the 5500C and 5501A operating and service manuals.

5501A-6. All serials. Notification of new service kits.

5505A-6. All serials. Notification of new service kits.

5505A-7. Serials1 948A and above. Measurement capabilities using plane mirror optics.

6140A DIGITAL CURRENT SOURCE

6140A-1. Serials 2004A-00344 and below. Modifica- tion to improve reliability of A526.

7010BR015B X-Y RECORDERS

7010B-1/7015B-1. Safety. Serials

2008

and below.

Modification to correct power select switch wiring.

7130/7131 STRIP CHART RECORDER

7130/7131-4. All serials. Options 28, 29, 30, 31 output clutch change for speed reducer options.

7310A PRINTERS

7310A-1. Serials 1941A00101 thru 1942AOO125. Rec- ommended replacement of 11 5-VAC fan motor in the event of failure.


8160A PROGRAMMABLE PULSE

GENERATOR

8160A-3. Serials 1804G00181 and below, and serials

1903G0021 1 and below. Power supply modification to improve performance.

8165A PROGRAMMABLE PULSE

GENERATOR

81 65A-2A. Serials 181 2000241 to 181 2G00281. Mod- ification to correct a power-on problem.

8165A-3A. Serials 1701G00101 to 1812GOO281. Mod- ification to improve power dissipation on A10.

8170A LOGIC PAlTERN GENERATOR

81 70A-3. Serials 191 5G00295 and below. Recom- mended replacement control board 081 70-66506,

Rev. D.

81 70A-4. Serials 191 5G00385 and below. Modification to improve external clock synchronization.

841 1A HARMONIC FREQUENCY

CONVERTER

841 1A-4. All serials.Step-by-step procedure for replacing sampler diode.

8566A SPECTRUM ANALYZER

8566A-1A. Serials 1904A and below. Preferred replacement for transistor A6A10011.

8568A SPECTRUM ANALYZER

8568A-8A. All serials. New sweep time accuracy performance test.

8568A-22. RF section prefix 1921A and below. Pre- ferred replacement for IC A17U2.

8568A-23. IF section prefix 1922A and above. Notifica- tion of new A3A6 system ROM signature analysis to improve performance.

8568A-24. CRT RFI shield cleaning.

8568A-26. RF section serial prefix 2007A and below.

Recommended PC board sockets to eliminate intermittent digital operation.

8568A-27. IF section serial prefix 2003A and above.

Modification to reduce noise floor.

8620C SWEEP OSCILLATOR

862OC-4. Serials 1933A and below. Option 01 1 HP-IB installation kit, HP part number 08620-601 54.

8662A SYNTHESIZED SIGNAL GENERATOR

8662A-2 Serials 1925A00170 and below Improved power supply reliability

11713A AlTENUATOR/SWITCH DRIVER

11713A-1 Serials 1850A and below Improved HP-IB operation

59309A HP/IB DIGITAL CLOCK

59309A-5 Modification to allow the use of large HP-IB connector on A2J2

59403A COMMON CARRIER INTERFACE

59403A-5 Serials 1426A01320 and below Modifica- tion to prevent inadvertent IFC generation

69423A LOW LEVEL A/D MULTl I CARD

69423A-1 Serials 1837A-00312 and below Modifica- tion to improve Performance

Service Notes

Service Notes from HP relating to personal safety and possible equipment damage are of vital importance to our customers. To make you more aware of these important notes, they are printed on paper with a red bor- der, and the service note number has

C l

-U 3 U l l l A . 111 U l U C l U J l l l i 3 K C

Y U U

immediately aware of any potential safety problems, we are highlighting safety-related service notes here with a brief description of each problem. Also, in order to draw your attention to safety-related service notes on the service note order form a t the back of Bench Briefs each appropriate number is highlighted by being printed in color.

I

7010B and 7015B

Recorders

X-Y

On recorders with serial number prefixs below 2008, the 11OACV

- the failure of U1, the power transformer becomes overheated with possible imminent failure.

The miswire is corrected by replac-

220ACV input power select switch switches as illustrated in the Safety has been miswired in the 220V posi- Service Note 7010B-1/7015B-l. tion. If the recorder is connected to ing a jumper on the voltage select

220V, the secondary k

16 volt supply For complete detailed instructions, rises above k

18 volts causing

U1

on please order the note with the order power board A4 to fail. In addition to form a t the back of Bench Briefs.

This Safety Service Note provides a warning to service personnel of the possibility of excessive CRT X-ray emissions should the high voltage power supply board be replaced or repaired.

Should a n y maintenance be per- formed, the high voltage power supply and intensity limit adjustment procedures in the

HP

1311B Operat- ing and Service manual (Section

V), or t h e procedures accompanying each replacement h i g h voltage power supply board must be strictly followed. Failure to do so could re- s‘

x

ET

c

f

-

- -

__

_ - _

_-


_ _ ~ -

Service Note Order Form

Instructions

If you want service notes, please check the appropriate boxes below and return this form separately one of the following addresses. to

For European customers (ONLY)

Hewlett-Packard

Central Mailing Dept.

P. 0.

Box 529

Van Hueven Goedhartlaan 121

AMSTELVEEN-1134

Netherlands

All Others

Hewlett-Packard

1820 Embarcadero Road

Palo Alto, California 94303

NAME

COMPANY NAME

ADDRESS

CITY

STATE ZIP

q

0

0

180ClD-4

:

400ElEL-11

0

1336A-1A

0

1350A-6

0

1610B-1

0

3311A-2

0

0

3467A-2

3571A-3

0

3738A-3

0

3745AlB-228

0

3747AlB-14

0

4328A-7

0

4943A-3

0

4943A-7

0

3771AlB-13

0

3771AlB-15

0

3777A-1

0

3779A-14

0

3779A-15

0

3779A-16

0

3779A-17

0

37798-14

0

3779B-15

0

0

4944A-6

5036A-1

0

5315AlB-1

0

53268153278-10

0

5328A-258

0

5328A-26

0

3791A-6

0

53638-1A

0

3792A-5

0

3793A-1

0

37938-1

0

3964A-1713968A-17

0

3964A-1813968A-18

0

5370A-6

0

5420A-22

WWW.HPARCHIVE.COM

0

5420A-23

0

5420A-24

0

0

5501A-6

-

0

5505A-6

5

701 58-1 (SAFETY)

0

816OA-3

0

8170A-3

0

0

0

8568A-23

8620C-4

59309A-5

..-.

COURSE DATE

0

0

0

I

O C C C

141

-

8552 -

8553

-

Aug. 6-8

8554

-

\

OJJJ

-

Sept. 15-19

-

Sept. 22-26

-

Sept. 29-Oct. 3 u {

8568A

-

Aug. 18-29

Oct. 20-31

3060

DTS-70

-

Nov. 17-21

.

.

$"

..

COST

$3OOlStudent

$400/Student

$2,10O/Student

$1,00O/Student

COORDINATOR1

LOCATION

J

I

J i m Boyer

1400 Fniint,ain Grnve

Parkway

- -

- -

-

-

Santa Rosa, CA 95404

(707) 525-1400

-

.

-

-

_.

Sandy Selleck

P.O. Box 301

Loveland, CO 80537

(303) 667-5000

Steve Thomas

1501 Page Mill Road

Palo Alto, CA 94304

$400/Student Aug. 25-29

Registration Instructions

To enroll in any of the seminars, contact your local HP office and specify the course desired. Please note that the 8566Al8568A

Spectrum Analyzer seminar is being re- peated three consecutive weeks. Contact the factory coordinator to specify which week you desire.

Upon receipt of your registration, we will confirm your enrollment by returning all necessary prestudy material along with a list of nearby motel accommodations and re- servation forms. Attendees are responsible for their own transportation, accommodations, and meals.

c-

1820 Ernbarcadero Road

Palo Alto, California 94303

Bulk Rate

US. Postage

BENCH

BRIEFS

MAY-JUNE 1980

Volume

20

Number

3

Service information from

Hewlett-Packard Company

To obtain a qualification form for a free subscription, send your request to the above address.

Reader comments or technical article contributions are welcomed. Please send them to the above address, attention Bench Briefs.

Editor: Jim Bechtold, HP Mt. View

California

Sunnyvale, CA.

Permit

No.

Address Correction Requested

Printed in

All rights are resewed

No part of bench Briefs may be reproduced without the express consent of the Edltor. The Editor may be telephoned at (415)

968-9200.

Extension 376

U.S.A.

.

....

.

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