YSI 80 Laboratory Recorder Operating instructions

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YSI 80 Laboratory Recorder Operating instructions | Manualzz
 YELLOW SPRINGS
INSTRUMENT CO.. INC.
YELLOW SPRINGS, OHIO 45387
INSTRUCTIONS
FOR |
“ YSI MODEL 80.
LABORATORY
RECORDER
INSTRUCTION BOOK YSI MODEL 80 RECORDER
CONTENTS
| Page
220 Volt information ..........o _.e0e0esaneroarraae recrearse rec 1
General Description .........eeoeececrcocoereoooorecarvarcermo 2
Specifications ..........e. tte tte ree re ae 3
Operating Instructions ........... i iii iii, 4
Input Characteristics ............. FH 5
Zero Offset Control Characteristics ............ civ... . 5
Unclamping of the Stylus ....... KHK 6
Chart Drive Instructions ...0000000000000000 000000 000020000000 6
Tear Off Operation .......220200 00000 00 0 00 a ee ae 0e eu a ea ea 0e 0 6
Schematic 2100000000 60 48 484 0 1 6 0 0 0 0 0e au es 000» Center Spread
Maintenance Procedure ..........oo_eonmcoceorrororoenoararacao 7
Removal of Front Panel Assembly ....................... Cee 7
Tube and Chopper Replacement .................... 0 0 ee 000 6 7
Recalibration ...................... ee 8
Maintenance of Mercury Cell . .. eK 8
Temperature Recording with YSI Tele-Thermometers. ............. . 8
Temperature Recording with Thermocouples . .................... 10
pH Reading with Beckman ZeromaticpH Meter . .................. 10
General Laboratory Recording ......... iii. 11
GUArANIEE «vv viii terete tiie eee eee 11
220 VOLT INFORMATION
If this instrument has been purchased as a 220 VAC Model, the fol-
lowing notes should apply to statements made in the instructions.
Power Requirements:
220 VAC — Operable from 190-250 VAC.
Wattage as stated in instructions.
Current requirements of instrument is % that stated.
Motor speeds and chart drive as stated in instructions.
The schematic contains notes indicating changes which have been
made to the circuit.
1
MODEL 80 LABORATORY RECORDER
GENERAL DESCRIPTION
The Model 80 Laboratory Recorder is a versatile general purpose D.C.
voltage and current recorder. The effective range of this instrument
extends from low level D.C. voltages and currents of 200 microvolts and
20 millimicroamperes up to 500 volts and 100 milliamperes. This exceed-
ingly wide range capability makes it a suitable instrument for a multitude
of laboratory and industrial applications.
The recording stylus is completely inkless and free from maintenance.
The stylus continuously follows the input signal, and every two seconds
is pressed against the pressure sensitive chart paper to mark a dot. These
dots join together to form a line. When input varies rapidly the record
becomes a dotted line with the change in input in two seconds repre-
sented by the horizontal distance beiween two dots. The recorder will
follow full chart width changes during the two seconds between marking.
The Model 80 circuit consists of an input network followed by a
chopper and a four-stage A.C. amplifier. The chopper converts the D.C.
input into a proportionate A.C. carrier signal which is amplified by the
A.C. amplifier. The output of the A.C. amplifier is synchronously rectified
and filtered. Stability, linearity, and high input impedance are main-
tained by the use of a large amount of inverse feedback.
Speed change is achieved simply by the interchanging of gear as-
semblies. The recorder is furnished with gear assemblies to drive the
chart at 1 inch per hour and 15 inches per hour. Six additional as-
semblies (2, 3, 6, 10, 12 and 30 inches per hour) are available, see chart
characteristics.
Three input terminals, HI, LO and GND are provided for either
grounded or floating input operation.
Input sensitivity may be selected in decade steps on the RANGE
switch. Intermediary sensitivity may be obtained with the SPAN control
which provides continuous adjustment between calibrated ranges.
The multi-turn ZERO OFFSET control permits zero left, zero center, or
zero right as well as up to 4 times full chart width zero suppression in
either direction on all ranges.
SPECIFICATIONS
Effective Instrument Range:
1. 200 microvolts to 500 volts.
2. 20 millimicroamperes to 100 milliamperes.
Sensitivity:
1. With the SPAN control in the RANGE CALIBRATED position, ten
calibrated ranges provide sensitivities from 200 microvolts per chart
division to 2 volts per chart division, and 20 millimicroamperes to 200
microamperes per chart division, accuracy =2% of range setting.
2. The SPAN control provides continuous adjustment between cali-
brated ranges and extends the minimum sensitivity to approximately
20 volts per chart division or 2 milliamperes per chart division.
Input Characteristics:
1. Either grounded or floating input (200 volts maximum above or
below ground).
2. Non-polarized input terminals and a continuous multi-turn ZERO
OFFSET control permit zero left, zero center, zero right, as well as up to
4 times full chart width zero suppression in either direction on all ranges.
3. 1 megohm input resistance on all voltage ranges.
4. 10 millivolts drop at full chart deflection for all current ranges
except 100 millivolts on 10 milliampere range.
Chart Characteristics:
1. Chart width: 2.31 inches.
2. Speed: 15 inches per hour and 1 inch per hour standard. Six addi-
tional assemblies, 2, 3, 6, 12 and 30 inches per hour are available. For
117 volt instrument operated on 50 Hz line Chart Speeds are 5/6 of
above. For 220 volt instrument operated on 60 Hz line Chart Speeds
are 6/5 of above.
3. Chart length: 63 feet.
4. Chart divisions: 50.
5. Response: recorder samples once every two seconds and will follow
full chart width. changes within sampling period without lag.
6. Chart take-up: built-in chart take-up reel or may be operated “tear-
off.”
7. Readability: 72%.
Stability: Better than 1% with normal variation. in line voltage and room
temperature, less than 2 minutes warm-up time required.
Power Requirements: 117 or 220 volts; 50-60 Hz, 15 watts.
Dimensions:
1. Size: 9%" x 5%" x 734".
2. Weight: 11 pounds.
WARNING
Absolute Maximum +500V for voltage recording.
Absolute Maximum 100 ma for current recording.
200 Volts max. for floated input
above or below ground.
Care should be exercised in unpacking the Model 80 recorder. It is
advisable to remove the back grill and perform a visual inspection to
check for seating of vacuum tubes, tube shield. It is important for proper
operation that the cable connector between the amplifier chassis and the
back of the recorder be securely plugged into the receptacle on the back
of the recorder box. After inspection replace the back grill.
The extra gear assembly supplied with the recorder is held in a
hinged compariment inside the recorder box. The compartment should
be snap fastened to the top of the recorder box. An extra gear assembly
retaining spring is also in the gear compartment. This is a reserve spring
in case of accidental loss or damage.
OPERATING INSTRUCTIONS
1. Mechanical zero adjustment: The stylus is the pointer of a meter
movement, and should be mechanicaliy aligned with the left chart line
with no electrical input to the movement. The alignment is correct when
the stylus, clamp bar, and left chart line intersect. This adjustment should
not be attempted with the POWER switch ON or with the stylus clamped.
Adjustment is accomplished with a screwdriver from the front of the
recorder unit. Accurate mechanical zero is not necessary since small
misalignments can be compensated with the ZERO OFFSET control.
2. Set RANGE switch to 0; rotate SPAN control clockwise to RANGE
CALIBRATED position.
3. Connect line cord to 117 v. 50-60 Hz outlet. If connected to a two-
wire supply system, using the line cord adaptor provided, ground the
green wire on the adaptor to a good earth ground. With a three-wire
supply system, external grounding is automatically provided and further
grounding is unnecessary, and (except in extraordinary circumstances)
should not be used.
4. Turn POWER switch ON and CHART DRIVE switch on.
5. Allow instrument to warm up for 2 minutes.
6. Adjust ZERO OFFSET control (a ten-turn control) for the desired
zero position which can be any position on the chart. In addition, the
zero may be set to 4 times chart width in either direction for suppressed
zero or expanded scale operation.
4
7. Connect input to HI and LO terminals and select desired range.
If input characteristics are not known zero should be set in the center
of the chart and consecutively lower ranges should be tried until a
deflection of the stylus is noticed. A deflection of one major division on
the chart paper represents full-scale deflection on the next lower range.
Stylus deflecis to the right for a positive signal connected to the HI
terminal.
INPUT CHARACTERISTICS
The Model 80 uses a conventional chopper amplifier provided with
heavy input filtering which discriminates against hum voltages applied
to the recorder input terminals by the signal source or the external wiring.
In some extreme cases, it may be necessary to provide shielded leads for
all external wiring in order to avoid the small recorder offsets (additive
or subtractive) resulting from the presence of too much hum at the input.
One of the most effective methods of reducing hum pickup at the input
is to ground one side of the input (LO or HI) to the GND terminal. This
method should always be used when it is electrically permissible to ground
one side of the input signal source. If, in addition, the signal being re-
corded is floating with respect to ground, it may be necessary to add an
external capacitor between the LO terminal and GND.
ZERO OFFSET CONTROL CHARACTERISTICS
The polarity and magnitude of the offset signal is adjusted by the
ZERO OFFSET control, enabling one to set a zero anywhere on the scale
(or on specific applications up to 4 times scale deflection off to the right
or left). |
The ZERO OFFSET signal is placed in series with the INPUT signal to
produce a total signal to the amplifier. However, to avoid confusion or
interaction with other controls the ZERO OFFSET signol is not affected by
the input RANGE switch or the SPAN control. Since the ZERO OFFSET
signal and the INPUT signal are connected in series to produce a total
input to the amplifier, the ZERO OFFSET signal can be viewed as adding
tc or subtracting from the INPUT signal depending on polarity.
The subtracting feature of the ZERO OFFSET can be used to advantage
in certain application known as “Expanded Scale” or “Suppressed Zero”
operation. For example: If a D.C. voltmeter indicates at all times in the
vpper half of the scale (i.e. meter readings are always in the range from
mid-scale to full-scale) it is possible to connect the input of the recorder
across the meter and record the upper half of the meter on the full-chart
width. Select a suitable range on the recorder and proceed to use the
ZERO OFFSET control to buck out the lower half scale signal from the
meter, so that the recorder reads zero when the meter reads half scale
and adjust sensitivity so that the recorder reads full-scale when the
5
meter also reads full-scale. These two operations must be repeated
several times until both settings are correct. The above example gives
a scale expansion factor of two.
UNCLAMPING OF THE STYLUS
The Model 80 can be used as an indicating vacuum tube voltmeter
or microammeter without performing trace recording. During such oper-
ation the stylus should be completely free to deflect with the CHART
DRIVE switch turned OFF. Turn off the swiich when the clamping bar is
just beginning to leave the stylus; the momentum of the drive motor
will then lift the clamping bar completely clear of the stylus.
CHART DRIVE INSTRUCTIONS
1. Loop paper around drive drum sliding between meter pointer
and backup roller.
2. Lift brake and insert supply roll.
3. Release gear train and pull paper
through to correct time. (Time indications
printed on the chart are of meaning only
in terms of one inch per hour operation.
Time references for other chart speeds
Drive should be marked on the chart through
Ny Drum the flip open window.) To release the gear
| train push the gear assembly in the direc-
tion of the arrow and hold.
4. Attach paper to reroll spool with
| tape.
5. Run the recorder chart to insure correct feeding of the paper.
CHART INSTALLATION
Brake
Supply
Roll —-
Reroll г Main Spacer
Зроо! ()
Top __
Roller
_ Pointer — ly «Striker
To change chart speeds change the gear assembly as follows: Remove
retainer spring by pulling top of spring toward paper drums and twisting
to remove from the hole at the bottom. This allows the gear assembly
to pivot far enough to completely disengage the retaining tabs. The gear
assembly can then be lifted up and out from the bottom. Reverse pro-
cedure to install a gear assembly.
Adjustments and Maintenance: There are no adjustments required. This
unit is factory adjusted for optimum performance. No oiling is required,
nor should ever be done. |
TEAR-OFF OPERATION
For convenience in short run recordings the recorder paper may be
operated tear-off. The following procedure will insure correct operatien.
1. Loosen thumb screw and open recorder door all the way.
2. Take reroll spool out of slots and remove all paper (if any) from
this spool. Replace empty spool and close retainers fo lock spools in slots.
6
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CHASSIS
All Resistors are Yaw 10%
Uniess Otherwise Specified
C-08017-T
All Capacitors are in ufd, =
NOTE: ON 220 VAC 50 Hz MODEL THE
FOLLOWING CHANGES ARE EFFECTIVE:
*1. 220 VAC 50 Hz
Model 80 Schematic “2. B-08057
"3. C-08062
3. Push gear assembly to release gear train; at same time pull out
about 5 inches of fresh paper, if 5 inches or more of used paper is avail-
able it is not necessary to pull out fresh paper. Tear off any excess beyond
5 inches.
4. Lift up recorder door so that end of paper can be threaded through
slot on top of recorder box. Close door slowly feeding paper through slot.
5. Pass end of paper under handle. This should leave about 1 inch of
paper overhanging the back of the recorder case.
6. To provide a small amount of tension on the paper any small
laboratory clamp can be clipped onto the end of the paper or any 1 or 2
ounce weight or a 50c coin can be taped to the end of the paper and
allowed to suspend over the back of the instrument case.
At the beginning of each tear-off run, it is recommended that the
recorder be run until internal gear train clearances are taken up before
starting to record.
MAINTENANCE PROCEDURE
General:
Excessive drift in the recorded trace and excessive noise in the output
resulting in uneven and broad trace line often indicates low gain and
noise in the amplifier. Malfunction in tubes and chopper is the major
cause of low gain and noise. When failure of these components is severe
the amplifier either has no output or the output is erratic and oscillatory.
Replacement of tubes and chopper is recommended as a first step in
maintenance followed by recalibration. Step by step procedures are given
in the following paragraphs. If compliance with proper procedures fails
to give satisfactory results, it is suggested the recorder be carefully packed
and returned to the factory for service.
REMOVAL OF FRONT PANEL ASSEMBLY FROM RECORDER CASE
1. Remove back grill — Remove four screws around the periphery
of the back grill. Lift out back grill passing line cord through slot at
bottom center.
2. Detach front panel assembly from the recorder case — First, remove
four screws from the top of the front panel (2 on extreme right and 2 on
extreme left). Second, remove the 3 remaining screws on the bottom of the
recorder case. Move the panel forward and out of the case. Turn the as-
sembly on its side with the recorder box down.
oe AND CHOPPER REPLACEMENT
. The input tube is an ECC83/12AX7. This tube is located in the
socket which has a tube shield.
2. The output tube is a 12AT7. This tube is not shielded. After re-
placement of tubes or chopper the recorder should be checked for noisy
7
trace and for possible non-linearity. If either symptom is present, different
tubes should be tried. It would also be wise to check calibration in these
circumstances.
3. If changing tubes and chopper does not correct the malfunction
noted the original tubes and chopper should be returned to the instru-
ment before the instrument itself is returned for service.
RECALIBRATION
Recalibration of the Model 80 recorder is easy to perform; either
voltage or current D.C. standards may be used. A simple circuit consisting
of a flashlight battery and variable resistors with an output monitored
by the standard (for example: a 1 milliampere or a 1 volt meter) can be
used as an input. The recalibration accuracy will be a function of the
accuracy of the standard. The following procedure is recommended.
1. Remove the back grill. Do not remove front panel assembly.
2. Perform the OPERATING INSTRUCTIONS as given in an earlier
pari of this manual; adjust for zero-left operation. Switch SPAN control
to RANGE CALIBRATED position.
3. In accordance with the standard being used, select the appropriate
full-scale RANGE. (Example: for a 1 ma. standard select 1 ma.)
4. Connect the standard input. Positive side to HI terminal, negative
to LO, and connect GND and LO together.
5. Adjust the CAL control located on the back-of the chassis for full-
scale deflection. Only one range need be calibrated for the complete
calibration of the instrument.
6. Replace back grill.
MAINTENANCE OF MERCURY CELL
The Model 80 uses one 1.34 v. mercury cell in the ZERO OFFSET
control circuit. The current drain is negligible and the cell should operate
for its full shelf life of 2 to 2% years. It is recommended that the cell be
changed for a fresh unit every two years. Replace with Mallory part
number RM625RT (or equivalent). The cell is easily accessible by remov-
ing the back grill.
TEMPERATURE RECORDING WITH YSI TELE-THERMOMETERS
The Model 80 Laboratory Recorder in conjunction with Yellow Springs
Instrument Company Tele-Thermometers is a complete temperature indi-
8
cating and recording system. A concise operating procedure is given as
an aid to this specific mode of operation.
All models of YSI Tele-Thermometers are battery powered Wheatstone
bridge temperature indicators with a thermistor probe as one arm of the
bridge. The indicator is a 50 microampere (1800 to 2000 ohm) D.C. meter
in a right hand zero configuration. At full-scale deflection the voltage
output (connected to the red and black jacks marked RECORDER) is 100
to 120 millivolts.
1. Connect a lead from red jack on thermometer to LO input terminal,
connect another lead from black jack to HI input terminal, and connect
HI input terminal to GND terminal on recorder with a third lead. Turn
thermometer OFF. |
2. Set RANGE switch to 100 mv., rotate SPAN control full counter-
clockwise (i.e. maximum attenuation or minimum sensitivity) and set
stylus to right edge of chart with ZERO OFFSET control.
3. The red line position on the thermometer scale provides a con-
venient reference on the temperature scale for adjusting the span of the
recorder. The percent of full-scale deflection of the red line temperature
can be calculated with the following procedure.
a=number of degrees between left hand end of scale and the red line.
b=total number of degrees in the range of the thermometer.
percent of full-scale deflection of red line temperature=(a- b) 100.
4. Turn thermometer on and set to red line. The recorder stylus should
now be set with the SPAN control to the same percentage of full-scale
deflection that red line is on the thermometer. For example: with a 0°C to
50°C range (range TD) the red line is at 5°C, or 10% (1 major division)
from left edge of the chart. This percentage must be determined for each
temperature range. |
5. Insert probe in telethermometer. The thermometer-recorder combi-
nation is now ready to indicate and record temperature.
A small portion of the thermometer scale can be made to cover
full-scale on the recorder by following the techniques for expanded scale
operation described under the section ZERO OFFSET CONTROL CHARAC-
TERISTICS. To facilitate this, substitute a decade resistance box for the
thermistor probe and vary values of resistance to give the desired tem-
perature points on the thermometer scale. (Example: for YSI interchange-
able probes substitute 7336 ohms at 0°C, 2253 ohms at 25°C, and 155
ohms at 100°C.) See YS| probe brochure for resistance values on YSI In-
terchangeable 400 Series Probes.
The technique of using a decade resistance box to simulate tempera-
ture can be used to calibrate exactly the recorder chart to the non-linear
scales of certain YSI thermometers such as the TE (—10 to +105°F).
9
TEMPERATURE RECORDING WITH THERMOCOUPLES
Since a thermocouple is a voltage generator whose output voltage is
proportional to temperature, a complete temperature indicating and re-
cording system is obtained by using the Model 80 recorder in conjunction
with the thermocouple in the following manner:
First adjust the Model 80 to the desired temperature range by setting
RANGE switch to 10 mv. Connect a voltage source corresponding to the
temperature at the low end of the range to the Hl and LO input terminals
plus voltage to HI terminal. (If the low temperature is the same as the
reference junction temperature this is O volts.) The ZERO OFFSET control
is then set to give a zero reading on the recorder. A voltage corresponding
to the high temperature is then applied to the .input terminals and the
SPAN control is adjusted to give full-scale deflection of the recorder stylus.
These two operations must be repeated several times until both set-
tings are correct.
Now connect the thermocouple to the input terminals of the Model 80
with the plus lead going to the HI terminal, the minus lead going to the LO
terminal and connect LO terminal to GND. The instrument is ready for use.
The above description applies to temperatures above the reference
junction temperature. To measure temperatures below the reference
junction the thermocouple leads are simply reversed at the input terminals
of the Model 80.
pH RECORDING WITH BECKMAN ZEROMATIC pH METER
First the Zeromatic should be modified for use with a recorder as
described in Zeromatic instruction book. The descriptions given there are
for either a current type or a voltage type recorder. Since the Model 80
is capable of performing as either type of recorder, the user has his
choice. There is perhaps a slight advantage to connecting the pH meter
for use with a voltage type recorder since a resistor can be put into the
pH meter permanently and the pH meter used either with or without a
recorder.
For voltage recording any stable resistor between 50 and 500 ohms
Ya W or more can be used since the Model 80 has an adjustable span.
The higher resistance values are slightly preferable since the recorder
is less sensitive to electrical “noise.”
After installing the resistor in the pH meter the recorder leads should
be attached with the HI lead going to the pH meter +, the LO lead
going to —. -
With the pH meter at center scale, the ZERO OFFSET control on th
Model 80 is used to set center scale on the recorder. Next the RANGE
switch is set to the 1 v. position, the SPAN control should be in the
RANGE CALIBRATED position, and the pH meter should be made to read
full-scale to the right. The RANGE switch on the Model 80 should. then be
switched to the position that causes the recorder pointer to go off-scale
10
to the right (100 mv. or 10 mv.) and the SPAN control adjusted to bring
the pointer back to full-scale. The system is then ready for use.
If it is not desirable to install a recorder resistor, the pH meter should
be modified for a current-type recorder (as described in the Zeromatic
instruction manual) and the Model 80 connected to the pH meter in the
manner described earlier. |
The Model 80 is adjusted in the same manner as described, except
the RANGE switch should start in the 0.1 ma. position. Then the pH meter
is set to read full-scale, and the SPAN control is used to bring the recorder
pointer back to full-scale.
If the pH meter is to be used without the recorder when set up for
current-type recording, the + and — terminals of the pH meter should
have a shorting lead connected between them.
GENERAL LABORATORY RECORDING
Almost any instrument that has a D.C. voltage or current meter for a
readout device can be recorded with a Model 80. This is done by merely
connecting the Model 80 input terminals across the meter in the correct
polarity and using the Model 80 on voltage settings of the RANGE switch.
This method of recording will work with any of the three common
types of meters: zero right, zero center, or zero left. The input terminals
are connected with the polarity that drives the recorder stylus in the
same direction as the meter pointer. When there is no signal from the
meter (i.e. no voltage drop across the meter) the ZERO OFFSET is adjusted
so that the recorder stylus is in any desired position (for example: zero
left, zero center, zero right).
The recorder can also be used for recording direct current in any
circuit that has no more than 100 ma. by merely opening the wire
through which the current is flowing and inserting the recorder. The
Model 80 can also be used for recording any D.C. voltage between 200
microvolts and 500 volts with one side of the circuit grounded and the
LO input terminal connected to the GND terminal, or between 200 micro-
volts and 200 volts if the circuit and the LO terminal are isolated from
ground. This is true for any circuit that is not affected by a 1 megohm
shunt resistance which is typical of many vacuum tube volt meters and
oscilloscopes.
GUARANTEE
The Model 80 Laboratory Recorder carries a 1 (one) year uncondi-
tional guarantee on all workmanship and components. Damage through
accident, misuse, or tampering will be repaired at a nominal charge
when the instrument is refurned to our plant.
11

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