Model 200 - Lake Shore Cryotronics, Inc.

USER’S MANUAL
Model 200
Temperature Monitor
Lake Shore Cryotronics, Inc.
575 McCorkle Boulevard
Westerville, Ohio 43082-8888 USA
E-Mail Addresses:
sales@lakeshore.com
service@lakeshore.com
Visit Our Website:
www.lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
Methods and apparatus disclosed and described herein have been developed solely
on company funds of Lake Shore Cryotronics, Inc. No government or other
contractual support or relationship whatsoever has existed which in any way affects or
mitigates proprietary rights of Lake Shore Cryotronics, Inc. in these developments.
Methods and apparatus disclosed herein may be subject to U.S. Patents existing or
applied for. Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or
withdraw functions, design modifications, or products at any time without notice. Lake
Shore shall not be liable for errors contained herein or for incidental or consequential
damages in connection with furnishing, performance, or use of this material.
Rev. 1.2
P/N 119-024
10 June 1999
Lake Shore Model 200 User’s Manual
LIMITED WARRANTY
Lake Shore Cryotronics, Inc. (henceforth Lake Shore), the manufacturer, warrants this
product for a period of twelve (12) months from the date of shipment. During the
warranty period, under authorized return of instruments or component parts to Lake
Shore freight prepaid, the company will repair, or at its option replace, any part found
to be defective in material or workmanship, without charge to the Owner for parts,
service labor or associated customary shipping cost. Replacement or repaired parts
will be warranted for only the unexpired portion of the original warranty.
All products are thoroughly tested and calibrated to published specifications prior to
shipment. Calibration Certifications are offered for six month periods only. Where
such documentation must be updated, a re-certification service is offered by Lake
Shore at a reasonable cost.
LIMITATION OF WARRANTY
This warranty is limited to Lake Shore products purchased and installed in the United
States. This same protection will extend to any subsequent owner during the warranty
period. It does not apply to damage caused by accident, misuse, fire, flood, or acts of
God, from failure to properly install, operate, or maintain the product in accordance
with the printed instructions provided. This warranty does not apply to defects
resulting from improper or inadequate maintenance, unauthorized modification or
misuse, operation outside of the environmental specifications for any product or part
or buyer-supplied software interfacing.
THIS WARRANTY IS IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED OR
IMPLIED, INCLUDING MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE, WHICH ARE EXPRESSLY EXCLUDED. THE OWNER AGREES THAT
LAKE SHORE’S LIABILITY WITH RESPECT TO THIS PRODUCT SHALL BE SET
FORTH IN THIS WARRANTY, AND INCIDENTAL OR CONSEQUENTIAL
DAMAGES ARE EXPRESSLY EXCLUDED.
CERTIFICATION
Lake Shore certifies that this product has been inspected and tested in accordance
with its published specifications and that this product met its published specifications
at the time of shipment. The accuracy and calibration of this product at the time of
shipment are traceable to the United States National Institute of Standards and
Technology (NIST); formerly known as the National Bureau of Standards (NBS), or to
a recognized natural standard.
TRADEMARK ACKNOWLEDGEMENT
Manufacturers and sellers claim many designations as trademarks to distinguish their
products. Where those designations appear in this manual and Lake Shore was
aware of a trademark claim, the designations appear in initial capital letters with a ™
®
or symbol.
CalCurve™, Carbon-Glass™, Cernox™, Quad-Lead™, and Quad-Twist™
are trademarks of Lake Shore Cryotronics, Inc.
®
Teflon is a trademark of DuPont De Nemours.
®
Apiezon is a trademark of Biddle Instruments.
Copyright © 1992, 1997, and 1999 Lake Shore Cryotronics, Inc. All rights reserved.
No portion of this manual may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopying,
recording, or otherwise, without the express written permission of Lake Shore.
A
Lake Shore Model 200 User’s Manual
TABLE OF CONTENTS
Chapter/Paragraph
1
General ..........................................................................2-1
Inspection and Unpacking..............................................2-1
Repackaging For Shipment ...........................................2-1
Front and Rear Panel Definitions ...................................2-2
Model 200 Definitions .................................................2-2
Model 200-S Definitions .............................................2-4
Model 200-D Definitions .............................................2-6
Sensor Installation Recommendations ..........................2-8
Two-Lead Measurement Considerations....................2-8
Connecting Leads ......................................................2-8
Sensor Mounting ........................................................2-9
Current Source Dependence....................................2-10
Measurement Errors Due To AC Noise ....................2-11
Sensor Curve Definition ...............................................2-12
Power Connections ......................................................2-13
Panel Mounting ............................................................2-13
Initial Setup and Checkout Procedure .........................2-14
OPERATION ................................................................................3-1
3.0
3.1
3.2
3.3
3.4
4
General ..........................................................................1-1
Model 200 System Description ......................................1-1
INSTALLATION ...........................................................................2-1
2.0
2.1
2.2
2.3
2.3.1
2.3.2
2.3.3
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.5
2.6
2.7
2.8
3
Page
INTRODUCTION ..........................................................................1-1
1.0
1.1
2
Title
General ..........................................................................3-1
Temperature Unit Selection ...........................................3-1
Diode Curve Selection ...................................................3-1
Blinking Decimal Point ...................................................3-1
Front Panel Operation....................................................3-2
SERVICE......................................................................................4-1
4.0
4.1
4.2
4.3
4.4
General ..........................................................................4-1
General Troubleshooting................................................4-1
Operating Software Replacement ..................................4-1
Model 200 PCB Description ...........................................4-3
Calibration......................................................................4-3
APPENDIX A – CURVE TABLES ...................................................... A-1
Table of Contents
i
Lake Shore Model 200 User’s Manual
LIST OF ILLUSTRATIONS
Figure No.
Title
Page
1-1
Model 200 Temperature Monitor Series....................................1-3
2-1
2-2
2-3
2-4
2-5
2-6
Model 200 Front Panel..............................................................2-2
Model 200 Rear Panel ..............................................................2-3
Model 200-S Front Panel ..........................................................2-4
Model 200-S Rear Panel...........................................................2-5
Model 200-D Front Panel..........................................................2-6
Model 200-D Rear Panel ..........................................................2-7
4-1
Location of Fuse and Jumpers .................................................4-2
LIST OF TABLES
Table No.
Title
Page
1-1
Model 200 Specifications ..........................................................1-4
2-1
2-2
Effect of Current Variation on Diode Temperature..................2-10
Typical DT-470 dV/dI Values for Selected Temperatures.......2-11
A-1
A-2
Lake Shore Standard Diode Curves ........................................ A-1
CTI Diode Curve ...................................................................... A-2
ii
Table of Contents
Lake Shore Model 200 User’s Manual
CHAPTER 1
INTRODUCTION
1.0
GENERAL
The Model 200 was designed and manufactured in the United States of
America by Lake Shore Cryotronics, Inc. The Model 200 features the
following:
• Bright 4-Digit LED Display of Temperature in K or °C
• Temperature Range: 1.4 K to 475 K (–271 °C to 202 °C)
• Resolution of ±0.1 K or °C
• Overall Accuracy with Calibrated Sensor of ±0.25 K
• Standard Temperature Response Curves, Plus Memory
for Precision Curve Option for a Calibrated Sensor
• Sensor Connections made to Screw Terminal Adapter
• Flexible Power Supply Requirement
We welcome comments on this manual. Although we try to keep it errorfree, some may occur. To report an error, describe it briefly and include the
appropriate paragraph, figure, table, and page number. Send comments to
Lake Shore Cryotronics, Attn: Technical Publications, 575 McCorkle Blvd.,
Westerville, Ohio 43082-8888. This manual is subject to change without
notice.
1.1
MODEL 200 SYSTEM DESCRIPTION
The Model 200 Temperature Monitor is a microcontroller-based instrument
which measures temperature. It is designed to use Lake Shore DT-470
Series and TG-120 Series diode sensors. The Model 200 displays the
temperature reading of one diode sensor. The Model 200-S has two inputs
and one display. The user selects the input to display by means of a front
panel switch. The diode sensors must conform to the same temperature
response curve. The Model 200-D has two inputs and two displays. The
readings of both diode sensors continuously display. Each sensor can have
its own temperature response curve. See Figure 1-1.
The Model 200 Temperature Monitor, coupled with the DT-470 Series or
TG-120 Series diode sensors, offers outstanding performance and
advantages over traditional thermocouple solutions. In the cryogenic
temperature range, the diode sensor offers a much higher signal and better
sensitivity, repeatability, and accuracy than a thermocouple. The DT-470
Series sensors follow the same temperature response curve, Curve 10. In
most applications they are interchangeable with no need to reconfigure
monitors. TG-120 Series sensors, which are more sensitive than DT-470
Series sensors at temperatures below 50 K, are recommended for magnetic
fields up to 5 tesla.
Introduction
1-1
Lake Shore Model 200 User’s Manual
Model 200 System Description (Continued)
Diode sensors come in several packaging formats for easy mounting. Unlike
a thermocouple, the lead wire in a diode measurement is not the active
sensor component; using an additional connector to bring out the sensor
signal from a cryogenic and/or vacuum system does not degrade the
measurement. Finally, the diode sensor does not require any room
temperature compensation.
The Model 200 excites the diode sensor with a 10 µA current source. An
analog-to-digital converter reads the sensor voltage and sends the reading
to a microcontroller. The microcontroller uses the selected temperature
response curve stored in memory to convert sensor voltage to temperature.
The computed temperature displays on the bright front panel LED display.
The Model 200 comes with several standard temperature response curves.
In applications where additional accuracy of a calibrated sensor is required,
order the Model 200 with a factory installed precision temperature response
curve. TG-120 diode sensors require a Model 200 with the precision
calibration option.
Mounting the Model 200 is simple since it is packaged in a 1/8 DIN
aluminum panel mount box. The 200-S and 200-D Temperature Monitors
are packaged in 1/4 DIN aluminum panel mount boxes.
1-2
Introduction
Lake Shore Model 200 User’s Manual
Model 200
°C
LakeShore
200 Temperature Monitor
K
Model 200-S
Sensor B
Sensor A
LakeShore
200-S Temperature Monitor
Channel A
°C
Model 200-D
Channel B
K
LakeShore
200-D Temperature Monitor
C-200-1-1.eps
Figure 1-1. Model 200 Temperature Monitor Series
Introduction
1-3
Lake Shore Model 200 User’s Manual
Table 1-1. Model 200 Specifications
THERMOMETRY
Input/Display:
Model 200
One input, one display
Model 200-S Two inputs, one display
Model 200-D Two inputs, two displays
Measurement type:
Two-lead
Sensor Type:
Silicon or GaAlAs Diode
Input Voltage Range: 5 Volts
Sensor Excitation:
10 µA ±0.2%
Temperature Range: 1.4–475 K with DT-470 Series Silicon
Diodes, 4.0–325 K with TG-120P or PL
Diodes, 4–500 K with TG-120-SD
Electronic Accuracy with Silicon Diode Sensor:
±0.1 degree typical, ±0.2 degree maximum
Accuracy with Calibrated Sensor: ±0.25 K
Sensor Curves:
Curve 10, D-Curve, CTI-Curve, and
Precision Option Curve. One CalCurve for
200/200-S, two for 200-D (factory installed).
DISPLAY
Type:
Resolution:
Units:
Update Rate:
4-Digit Red LED Display, 14.2 mm
(0.56 in.) high, and unit annunciators
0.1 K or °C
K or °C
3 updates per second
REAR PANEL CONNECTORS AND SWITCHES
Sensor Input:
Screw terminal
Power Input:
Power jack accepts power plug
compatible to Switchcraft S-760 or S-765
or screw terminal
Configuration Switch: 4-position DIP Switch to Select Curve and
Temperature Unit
GENERAL
Ambient Temperature Range: 15–35 °C
Power Requirements: 20–35 VDC or 15–24 VAC (50-60 Hz),
3.5 Watts (Maximum)
Size:
Model 200 = 96 x 48 x 146 mm
(3.78 x 1.89 x 5.75 in.);
Model 200-S & 200-D = 96 x 96 x 146 mm
(3.78 x 3.78 x 5.75 in.)
Panel Mount Cutout Dimensions:
Model 200 = 91 x 44 mm (3.58 x 1.72 in.);
Model 200-S & 200-D = 91 x 96 mm
(3.58 x 3.58 in.)
1-4
Introduction
Lake Shore Model 200 User’s Manual
CHAPTER 2
INSTALLATION
2.0
GENERAL
This chapter covers Inspection and Unpacking (Paragraph 2.1), Repackaging
for Shipment (Paragraph 2.2), Front and Rear Panel Definitions (Paragraph
2.3), Sensor Installation Recommendations (Paragraph 2.4), Sensor
Definitions (Paragraph 2.5), Power Connections (Paragraph 2.6), Panel
Mounting (Paragraph 2.7), and Initial Setup and Checkout (Paragraph 2.8)
2.1
INSPECTION AND UNPACKING
Inspect shipping containers for external damage. Make all claims for
damage (apparent or concealed) or partial loss of shipment in writing to
Lake Shore within five (5) days from receipt of goods. If damage or loss is
apparent, please notify the shipping agent immediately.
Open the shipping containers. Use the packing list included with the system
to verify receipt of the instrument, sensor, accessories, and manual. Inspect
for damage. Inventory all components supplied before discarding any
shipping materials. If there is freight damage to the instrument, file proper
claims promptly with the carrier and insurance company and notify Lake
Shore. Notify Lake Shore immediately of any missing parts. Lake Shore
cannot be responsible for any missing parts unless notified within 60 days of
shipment. See the standard Lake Shore Warranty on the A Page
(immediately behind the title page).
2.2
REPACKAGING FOR SHIPMENT
To return the Model 200 or accessories for repair or replacement, obtain a
Return Goods Authorization (RGA) number from Technical Service in the
United States, or from the authorized sales/service representative from
which the product was purchased. Instruments may not be accepted without
a RGA number. When returning an instrument for service, Lake Shore must
have the following information before attempting any repair.
1.
2.
3.
4.
5.
Instrument model and serial number.
User name, company, address, and phone number.
Malfunction symptoms.
Description of system.
Returned Goods Authorization (RGA) number.
Repack the system in its original container (if available). Affix shipping
labels and FRAGILE warnings. Write RGA number on the outside of the
container or on the packing slip. If not available, consult Lake Shore for
shipping and packing instructions.
Installation
2-1
Lake Shore Model 200 User’s Manual
2.3
FRONT AND REAR PANEL DEFINITIONS
This paragraph defines front and rear panels of the Model 200 (Paragraph
2.3.1), Model 200-S (Paragraph 2.3.2), and Model 200-D (Paragraph 2.3.3).
2.3.1
Model 200 Definitions
The Model 200 has no front panel controls. The 4-digit red LED displays the
temperature in Kelvin (K) or degrees Celsius (°C). Select temperature units
with the rear panel DIP switch. See Figure 2-1.
°C
LakeShore
200 Temperature Monitor
C-200-2-1.eps
Figure 2-1. Model 200 Front Panel
The rear panel consists of the 24 Volt power input connector, DIP Switch,
CAL trimpot, and screw-terminal connector. See Figure 2-2.
24 Volt Power Input Connector. The line cord from the wall mounted
power supply has a power plug that inserts into the Model 200 rear panel.
The Model 200 is off when not plugged in, and on when plugged in. Make
sensor connections before applying power to the instrument.
DIP Switch. The DIP switch controls temperature display and curve
selection. The first switch, labeled K/C, selects Kelvin or degrees Celsius for
display. The next two switches select the proper sensor curve as shown in
the table below. The four curve types are defined in Paragraph 2.5. The
fourth switch is not used.
2-2
CURVE 1
CURVE 0
SETTING
OPEN
OPEN
CLOSE
CLOSE
OPEN
CLOSE
OPEN
CLOSE
DT-470
CTI-Curve
D-Curve
Precision Option
Installation
Lake Shore Model 200 User’s Manual
Model 200 Definitions (Continued)
CAL Trimpot. The CAL trimpot adjusts instrument calibration. See
Paragraph 4.4 for details.
1
2
3
CAL
SHIELD
K/C
CURVE 1
CURVE 0
POWER
24
OPTIONAL
POWER
24
VREF
Screw-Terminal Connector. The diode terminals are marked + for the
anode and – for the cathode. VREF and Shield are used during unit
calibration. See Paragraph 4.4 for details. Shield also terminates the diode
sensor cable shield. Finally, the power for multiple Model 200's can be
ganged together to a common on/off switch using the Optional Power input,
which is the first two inputs on the screw-terminal connector. This is an input
only, and can not be used as a voltage tap.
4
- - - OPEN - - -
C-200-2-2.eps
Figure 2-2. Model 200 Rear Panel
Installation
2-3
Lake Shore Model 200 User’s Manual
2.3.2
Model 200-S Definitions
The Model 200-S has one front panel control. The Sensor A/Sensor B
switch selects which sensor data to display. Both sensors must conform to
the same temperature response curve. The 4-digit red LED displays the
selected temperature in Kelvin (K) or degrees Celsius (°C).
K
Sensor A
Sensor B
LakeShore
200-S Temperature Monitor
C-200-2-3.eps
Figure 2-3. Model 200-S Front Panel
2-4
Installation
Lake Shore Model 200 User’s Manual
Model 200-S Definitions (Continued)
The Model 200-S rear panel is the same as the Model 200 except: The
upper screw-terminal connector applies to Sensor A. The lower screwterminal connector applies to Sensor B. The front panel switch selects
between the two sensors. Both sensors must conform to the same
temperature response curve selected by the CURVE 1 and CURVE 0
DIP switches. There is only one POWER connector and DIP Switch
(see Paragraph 2.3.1).
1
2
3
SHIELD
Sensor A
VREF
K/C
CURVE 1
CURVE 0
POWER
24
OPTIONAL
POWER
24
CAL
4
- - - OPEN - - -
SHIELD
NC
NC
NC
Sensor B
C-200-2-4.eps
Figure 2-4. Model 200-S Rear Panel
Installation
2-5
Lake Shore Model 200 User’s Manual
2.3.3
Model 200-D Definitions
The Model 200-D has no front panel controls. Two 4-digit red LEDs
simultaneously display temperatures in Kelvin (K) or degrees Celsius (°C).
In essence, the Model 200-D operates as two independent Model 200 units
with a common power supply.
Channel A
°C
Channel B
K
LakeShore
200-D Temperature Monitor
C-200-2-5.eps
Figure 2-5. Model 200-D Front Panel
2-6
Installation
Lake Shore Model 200 User’s Manual
Model 200-D Definitions (Continued)
Descriptions of the Model 200-D rear panel are the same as the Model 200
except two complete sets of DIP switches (see Paragraph 2.3.1), CAL
trimpots, and screw-terminal connectors are provided. The upper set applies
to Channel A. The lower set applies to Channel B. The unit simultaneously
displays the temperatures of both sensors. There is only one POWER
connector.
1
2
3
SHIELD
VREF
NC
NC
K/C
CURVE 1
CURVE 0
Channel A
CAL
4
- - - OPEN - - -
1
2
3
VREF
Channel B
SHIELD
K/C
CURVE 1
CURVE 0
POWER
24
OPTIONAL
POWER
24
CAL
4
- - - OPEN - - -
C-200-2-6.eps
Figure 2-6. Model 200-D Rear Panel
Installation
2-7
Lake Shore Model 200 User’s Manual
2.4
SENSOR INSTALLATION RECOMMENDATIONS
Abbreviated sensor installation recommendations for the Model 200 are
included in this section. Please refer to the Lake Shore Product Catalog for
installation details and sensor specifications. Call Lake Shore for copies of
application notes or with questions or comments concerning sensor
installation.
1.
Do not ground the sensor.
2.
Shield leads and connect shield wire to SHIELD on screw terminal
connector only. Do not connect shield at other end of cable.
3.
Keep leads as short as possible.
4.
Use twisted-pair wire. Use Lake Shore Duo-Twist™ wire (or equivalent)
for two-wire, or Quad-Twist™ wire (or equivalent) for four-wire
applications.
5.
Thermally anchor lead wires.
2.4.1
Two-Lead Measurement Considerations
In two-lead measurement, the leads measuring sensor voltage are also the
current carrying leads. The resultant voltage measured at the instrument is
the sum of the temperature sensor voltage and the IR voltage drop within
the two current leads. In a cryogenic environment, the heat flow down the
leads is of critical concern, so wire of small diameter and significant
resistance per foot is preferred to minimize heat flow. Consequently, a
voltage drop within the leads may exist.
Expect some loss in accuracy since the voltage measured at the voltmeter
is the sum of the sensor voltage and the voltage drop across the connecting
leads. The exact measurement error depends on sensor sensitivity and
variations resulting from changing temperature. For example, a 10 lead
resistance results in a 0.1 mV voltage error. The resultant temperature error
at liquid helium temperature is only 3 mK, but because of the lower
sensitivity (dV/dT) of the diode at higher temperatures, it becomes 10 mK at
liquid nitrogen temperature.
2.4.2
Connecting Leads To The Sensor
Excessive heat flow through connecting leads to any temperature sensor
may differ the temperature between the active sensing element and the
sample to which the sensor mounts. This reflects as a real temperature
offset between what is measured and the true sample temperature.
Eliminate such temperature errors with proper selection and installation of
connecting leads.
To minimize heat flow through the leads, select leads of small diameter and
low thermal conductivity. Phosphor-bronze or Manganin wire is commonly
used in sizes 32 or 36 AWG. These wires have a fairly low thermal
conductivity, yet electrical resistance is not large enough to create
measurement problems.
2-8
Installation
Lake Shore Model 200 User’s Manual
Connecting Leads To The Sensor (Continued)
Thermally anchor lead wires at several temperatures between room
temperature and cryogenic temperatures to guarantee no heat conduction
through the leads to the sensor.
2.4.3
Sensor Mounting
Before installing a diode sensor, identify which lead is the anode and which
is the cathode. When viewed with the base down and the leads towards the
observer, the anode is on the right and the cathode is on the left. The Lake
Shore DT-470-SD silicon diode sensor lead configuration is shown to the
right. For other sensors, read accompanying literature or consult the
manufacturer to positively identify sensor leads. Lead identification should
remain clear even after sensor installation. Record the sensor serial number
and location.
DT-470-SD
Diode Sensor Leads
Cathode
Anode
On the DT-470-SD, the base is the largest flat surface. It is sapphire with
gold metalization over a nickel buffer layer. The base is electrically isolated
from the sensing element and leads; make all thermal contact to the sensor
through the base. A thin braze joint around the sides of the SD package
electrically connect to the sensing element. Avoid contact to the sides with
any electrically conductive material.
When installing the sensor, make sure there are no electrical shorts or
current leakage paths between the leads or between the leads and ground.
If IMI-7031 varnish or epoxy is used, it may soften varnish-type lead
insulations so that high resistance shunts appear between wires if sufficient
time for curing is not allowed.
®
Slide Teflon spaghetti tubing over bare leads when the possibility of
shorting exists. Avoid putting stress on the device leads and allow for
thermal contractions that occur during cooling which could fracture a solder
joint or lead if installed under tension at room temperature.
For temporary mounting in cold temperature applications, apply a thin layer
®
of Apiezon N Grease between the sensor and sample to enhance thermal
contact under slight pressure. The preferred method for mounting the
DT-470-SD sensor is the Lake Shore CO Adapter.
Installation
2-9
Lake Shore Model 200 User’s Manual
Sensor Mounting (Continued)
CAUTION: Lake Shore will not warranty replace any device damaged by
user-designed clamps or solder mounting.
®
For semi-permanent mountings, use Stycast epoxy instead of Apiezon N
Grease.
NOTE: Do not apply Stycast epoxy over the DT-470-SD package: sensor
stress may shift the readings. In all cases, periodically inspect the sensor
mounting to verify good thermal contact to the mounting surface is
maintained.
2.4.4
Current Source Dependence
This paragraph addresses the effects of current source accuracy on
temperature measurement accuracy. Although the Model 200 has an
accurate internal current source, it is important to understand the
relationship between current variation and measurement accuracy.
Diode sensors possess a non-linear forward current-voltage characteristic.
Consequently, the forward voltage variation with changing current for diodes
is smaller than for resistance temperature sensors, which have linear
current-voltage characteristics.
Below 30 K, the sensitivity (dV/dT) of Lake Shore diode temperature
sensors increases by an order of magnitude over sensitivities at higher
temperatures. The slope (dV/dI) of the I-V curves stays relatively constant.
Both characteristics reduce even further the effect of any change in
forward bias current on temperature measurement accuracy. Refer to
Tables 2-1 and 2-2.
Table 2-1. Effect of Current Variation
on Diode Temperature Measurement Accuracy
T (K)
I, µA*
300
0.5
0.05
0.005
5
0.5
0.05
9.5 to 10.5
9.95 to 10.05
9.995 to 10.005
1
0.1
0.01
150
1
0.1
0.01
0.005
10
1
0.1
0.05
9 to 11
9.9 to 10.1
9.99 to 10.01
9.995 to 10.005
1
0.1
0.01
0.005
50
3
0.3
0.03
0.005
30
3
0.3
0.05
7 to 13
9.7 to 10.3
9.97 to 10.03
9.995 to 10.005
1
0.1
0.01
0.005
Acc. (%)*
Range (µA)*
Error (K)
* With current source (I10 µA).
2-10
Installation
Lake Shore Model 200 User’s Manual
Current Source Dependence (Continued)
If the output from a current source is not precisely 10 µA, the error in
temperature can be calculated by this relationship between the dV/dT and
dV/dI values: DT = (DI • dV/dI) / (dV/dT)
Note values dV/dI and dV/dT are derived at same temperature (T).
Table 2-2. Typical DT-470 dV/dI Values for Selected Temperatures
T (K)
300
77
4.2
2.4.5
dV/dI (approx.)
3000 1000 2800 Measurement Errors Due To AC Noise
Poorly shielded leads or improperly grounded measurement systems can
introduce AC noise into the sensor leads. In diode sensors, the AC noise
shifts the DC voltage measurement due to the diode non-linear
current/voltage characteristics. When this occurs, measured DC voltage is
too low and the corresponding temperature reading is high. The
measurement error can approach several tenths of a Kelvin. To determine if
this problem exists, perform either procedure below.
1.
Place a capacitor across the diode to shunt induced AC currents.
Capacitor size depends on the noise frequency. If noise is related to
power line frequency, use a 10 microfarad capacitor. If AC-coupled
digital noise is suspected (digital circuits or interfaces), use a 0.1 to 1
microfarad capacitor. In either case, if measured DC voltage increases,
there is induced noise in the measurement system.
2.
Measure AC voltage across the diode with an AC voltmeter or
oscilloscope. Most voltmeters do not have the frequency response to
measure noise associated with digital circuits or interfaces (which
operate in the MHz range). For a thorough discussion of this potential
problem, and the magnitude of error which may result, request the
paper “Measurement System-Induced Errors In Diode Thermometry,”
J.K. Krause and B.C. Dodrill, Rev. Sci. Instr. 57 (4), 661, April, 1986
from Lake Shore.
To greatly reduce potential AC noise, connect twisted leads (pairs) between
the measurement instruments and the diode sensors. Use 32 or 36 AWG
Lake Shore Duo-Twist™ Cryogenic Wire, which features phosphor bronze
wire twisted at 3.15 twists per centimeter (8 twists per inch). See the Lake
Shore Product Catalog or contact Lake Shore for further information.
Installation
2-11
Lake Shore Model 200 User’s Manual
2.5
SENSOR CURVE DEFINITION
Sensor curves available with the Model 200 include Curve 10, CTI-Curve,
D-Curve, and a factory installed Precision Option for a calibrated sensor.
After selecting the proper curve, set the Model 200 rear panel DIP switch
(see Paragraph 3.2).
Curve 10. Lake Shore DT-470 Series silicon diodes follow the same
standard temperature response Curve 10 and are interchangeable.
Curve 10 is programmed into all Lake Shore Temperature Controllers,
digital thermometers, and temperature monitors. DT-470 Series sensors
come in five bands of tracking accuracy.
Standard Curve 10
Forward Voltage ­ Vf (volts)
1.8
1.6
1.4
Average
Slope
­26 mV/K
1.2
1.0
0
10
20
30
40
50
60
0.8
0.6
Average
Slope
­2.3 mV/K
0.4
0.2
0
20
60
200
300
Temperature, K (kelvin)
CTI-Curve. For Customer convenience, the Model 200 also supports the
standard curve for CTI-Cryogenics diodes.
D-Curve. Users of older Lake Shore DT-500 Series diode sensors can still
use the Model 200 when set to D-Curve.
Precision Option. The Precision Option is the easiest way to combine the
additional performance of a Lake Shore calibrated sensor with the Model
200 Temperature Monitor. This option is a read-only memory chip (PROM)
with specific sensor calibration stored on it. It improves combined
sensor/instrument accuracy to within ±0.25K or better over the calibrated
temperature range of the sensor.
The factory installs the 8001-200 Precision Option on instruments ordered
with a calibrated sensor. To use the instrument with an existing Lake Shore
calibrated sensor, Lake Shore requires the sensor model and serial
numbers at the time of order. The Model 8002-200 is for field installations of
the Precision Option in an existing Model 200.
2-12
Installation
Lake Shore Model 200 User’s Manual
Sensor Curve Definition (Continued)
The Precision Option is required for Lake Shore TG-120 Series GalliumAluminum-Arsenide Diode Temperature Sensors.
2.6
POWER CONNECTIONS
The Model 200 accepts a broad power supply AC or DC voltage range from
any polarity power supply. If the Model 200 is ordered with a wall-mount
power supply, a 24 Volt AC power supply is included. The line cord from the
wall mounted power supply has a power plug that inserts into the 24 Volt
Connector on the Model 200 rear panel. The Model 200 is off when not
plugged in, and on when plugged in. Make sensor connections before
applying power to the instrument.
The power for multiple Model 200s can be ganged together to a common
on/off switch using the Optional 24-Volt Power Input, being the first two
inputs on the screw-terminal connector. This is an input only, and should not
be used as a voltage tap.
2.7
PANEL MOUNTING
1. Panel mount cutout dimensions: Model 200 = 91 x 44 mm (3.58 x
1.72 in.); Model 200-S & 200-D = 91 mm square (3.58 in. square).
2. Unplug the unit.
3. Use 1/16 inch hex wrench to remove two headless screws.
4. Remove two panel mount brackets by sliding towards rear of unit.
5. Place unit in panel cutout.
6. Slide two panel mount brackets into unit case.
7. Use 1/16 inch hex wrench to install two headless screws.
Installation
2-13
Lake Shore Model 200 User’s Manual
2.8
INITIAL SETUP AND CHECKOUT PROCEDURE
This procedure verifies basic unit operation.
1.
Verify proper wall-mount power supply is used. A wall-mounted power
supply is available that accommodates 90-130 VAC or 200-250 VAC
operation. The Model 200 requires a 24 Volt input.
CAUTION: Connect temperature sensor(s) to unit rear before applying
power. Sensor damage may occur if connected with power on.
2.
Install temperature sensor(s) per recommendations in Paragraph 2.4.
Route wiring to Model 200.
3.
Connect power plug to 24 Volt receptacle at unit rear, then plug wallmounted power supply into power connection.
4.
Upon power up, the unit displays one of the following codes, depending
upon the curve selected:
“CU0” = DT-470
“CU1” = CTI
“CU2” = D-Curve
“CU3” = Precision Option
5.
If sensor connections are correct and exhibit no opens or shorts, the
temperature displays and the decimal point blinks. (The rate of the
blinking corresponds to the update cycle.)
Sensor connection problems cause one of two messages display:
“OPEN” = Sensor connection loose, polarity backward, or not
connected.
“SHORT” = Wiring is shorted at some point between unit and sensor.
Upon successful completion of this abbreviated checkout procedure,
the unit is ready for normal operation.
2-14
Installation
Lake Shore Model 200 User’s Manual
CHAPTER 3
OPERATION
3.0
GENERAL
This chapter describes the front panel controls for each of the three models
in Paragraphs 3.1 thru 3.3.
K/C
CURVE 1
CURVE 0
3.1
TEMPERATURE UNIT SELECTION
The temperature scale displayed on the front panel is selected by a DIP
Switch labeled K/C on the rear panel. Depress the top portion of the switch
(closed) to select degrees Celsius. Depress the bottom portion of the switch
(open) to select Kelvin.
1
2
3
4
- - - OPEN - - -
3.2
DIODE CURVE SELECTION
Sensor curves available with the Model 200 include Curve 10, CTI-Curve,
D-Curve, and a factory installed Precision Option. See Paragraph 2.5 for a
definition of sensor curves.
The diode curve selected by the position of the two DIP Switches labeled
CURVE 1 and CURVE 0 on the rear panel. Depress the top portion of the
switch to select closed and the bottom portion of the switch to select open.
CURVE 1
CURVE 0
SETTING
OPEN
OPEN
CLOSE
CLOSE
OPEN
CLOSE
OPEN
CLOSE
DT-470
CTI-Curve
D-Curve
Precision Option
3.3
BLINKING DECIMAL POINT
The best indicator of a correctly functioning unit is a blinking decimal point.
The decimal point blinks at a rate corresponding to the unit update rate;
about 3 times per second.
Operation
3-1
Lake Shore Model 200 User’s Manual
3.4
FRONT PANEL OPERATION
The Model 200 has no front panel controls. The 4-digit red LED displays the
temperature in Kelvin (K) or degrees Celsius (°C). See Figure 2-1.
The Model 200-S has one front panel control. The Sensor A/Sensor B
switch is used to select which of two sensors temperature data is displayed.
Both sensors must conform to the same diode curve. The 4-digit red LED
displays the selected temperature in Kelvin (K) or degrees Celsius (°C). See
Figure 2-3.
The Model 200-D has no front panel controls. Two 4-digit red LEDs
simultaneously display temperatures in Kelvin (K) or degrees Celsius (°C).
In essence, the Model 200-D operates as two independent Model 200 units
with a common power supply. See Figure 2-5.
3-2
Operation
Lake Shore Model 200 User’s Manual
CHAPTER 4
SERVICE
4.0
GENERAL
This chapter cover General Troubleshooting (Paragraph 4.1), Operating
Software Replacement (Paragraph 4.2), the Model 200 Printed Circuit Board
(PCB) (Paragraph 4.3), and Calibration (Paragraph 4.4).
4.1
GENERAL TROUBLESHOOTING
If there is no power, first verify that 24 VAC is present. Next, check the fuse.
Open unit, remove fuse, and test fuse with ohmmeter. Do not rely on visual
inspection of fuse. See Figure 4-1. The fuse rating is 200 mA, Slow-Blow,
5 mm by 20 mm.
Upon power up, the sensor curve displays, where “CU0” = DT-470, “CU1” =
CTI, “CU2” = D-Curve, or “CU3” = Precision Option. If sensor connections
are correct, the temperature displays and the decimal point blinks. If there is
a problem, one of two messages display: “OPEN” = sensor connection is
loose, polarity backward, or not connected; or “SHORT” = wiring is shorted
at some point between unit and sensor.
4.2
Operating Software Replacement
The microprocessor IC (U10) contains the Model 200 operating software.
See Item 10 in Figure 4-1. Use the following procedure to replace the
operating software IC.
CAUTION: To avoid damaging the unit, disconnect unit from power supply
before performing this procedure.
1.
Disconnect power plug and screw terminal connector from unit rear.
2.
Remove four screws attaching rear panel to unit.
3.
Note location of PCB(s) in slots. Ensure DIP switch remains attached to
socket.
4.
Locate IC U10 on main circuit board. Note orientation of existing
EPROM (circular notch on front of IC).
5.
Use IC puller to remove existing IC from socket.
6.
Noting orientation of new IC, use IC insertion tool to place new IC into
socket.
7.
Slide PCB(s) into appropriate slot and replace rear panel.
8.
Reconnect power plug and screw terminal connector to unit rear.
Service
4-1
Lake Shore Model 200 User’s Manual

’
“
R14
‘
”
J2
J4
S1
F1
TP2
J3
J1

TP1
C9
•
Ž

U10
Œ
C4
Pin 1
C-200-4-1.eps
Figure 4-1. Location of Fuse and Jumpers
4-2
Service
Lake Shore Model 200 User’s Manual
4.3
MODEL 200 PCB DESCRIPTION
Below is a brief description of major components on the Model 200 Printed
Circuit Board (PCB). See Figure 4-1.
1.
Microprocessor/ROM (U10). This integrated circuit is a combination
microprocessor, program memory, and Precision Option Curve (if
present). Note orientation notch in Figure 4-1.
2.
Test Point 1 (TP1) – Corresponds to the Shield pin on the rear panel
connector (J4).
3. Test Point 2 (TP2) – Corresponds to the VREF pin on the rear panel
connector (J4).
4. Connector (J3) – 4-pin jumper connection (for Model 200-S only).
5. Connector (J4) – Screw terminal connector.
6. Trimpot (R14) – Calibration trimpot. Accessible from rear panel.
7. DIP Switch (S1) – Accessible from rear panel. Selects temperature
units and curve settings. The fourth switch is not used.
8. Connector (J2) – Power jack used to connect an external 24 Volt power
supply.
9. Connector (J1) – 2-pin jumper connection (for Model 200-D only).
10. Fuse (F1) – 200 mA, Slow Blow, 5 mm by 20 mm.
4.4
CALIBRATION
Calibrate the unit from the rear panel. Monitor the voltage between VREF
and Shield on the rear panel screw terminals with a good quality high input
impedance voltmeter. Adjust the CAL trimpot for a reading of 2.500 VDC.
Alternatively, a bare PCB may also be calibrated by monitoring TP1 (Shield)
and TP2 (VREF).
Service
4-3
Lake Shore Model 200 User’s Manual
This Page Intentionally Left Blank
4-4
Service
Lake Shore Model 200 User’s Manual
APPENDIX A
MODEL 200 CURVE TABLES
Table A-1. Lake Shore Standard Diode Curves
Breakpoint No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Appendix A
D-Curve
Temp.(K)
Voltage
499.9
365.0
345.0
305.0
285.0
265.0
240.0
220.0
170.0
130.0
090.0
070.0
055.0
040.0
034.0
032.0
030.0
029.0
028.0
027.0
026.0
025.0
023.0
021.0
017.0
015.0
013.0
009.0
003.0
001.4
000.0
0.00000
0.19083
0.24739
0.36397
0.42019
0.47403
0.53960
0.59455
0.73582
0.84606
0.95327
1.00460
1.04070
1.07460
1.09020
1.09700
1.10580
1.11160
1.11900
1.13080
1.14860
1.17200
1.25070
1.35050
1.63590
1.76100
1.90660
2.11720
2.53660
2.59840
6.55360
DT-470 Curve 10
Temp.(K)
Voltage
499.9
475.0
460.0
435.0
390.0
340.0
280.0
230.0
195.0
165.0
140.0
115.0
095.0
077.4
060.0
044.0
036.0
031.0
028.0
027.0
026.0
025.0
024.0
020.0
015.5
012.0
009.0
003.8
002.0
001.4
000.0
0.00000
0.09032
0.12536
0.18696
0.29958
0.42238
0.56707
0.68580
0.76717
0.83541
0.89082
0.94455
0.98574
1.02044
1.05277
1.08105
1.09477
1.10465
1.11202
1.11517
1.11896
1.12463
1.13598
1.21555
1.29340
1.36687
1.44850
1.64112
1.68912
1.69808
6.55360
A-1
Lake Shore Model 200 User’s Manual
Table A-2. CTI Diode Curve
Breakpoint No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
A-2
CTI Curve
Temp.(K)
Voltage
320.0
305.0
295.0
285.0
280.0
270.0
250.0
195.0
165.0
140.0
130.0
125.0
115.0
110.0
100.0
095.0
090.0
085.0
077.4
065.0
060.0
036.0
020.0
019.0
018.0
014.0
012.0
011.0
010.0
0.2968
0.3382
0.3640
0.3911
0.4050
0.4341
0.4896
0.6408
0.7255
0.7971
0.8245
0.8376
0.8625
0.8769
0.9049
0.9184
0.9314
0.9440
0.9626
0.9958
1.0100
1.0747
1.1162
1.1290
1.1500
1.3161
1.3656
1.3850
1.4000
Appendix A
NOTES
Lake Shore
is a technology leader in the
development of cryogenic
temperature sensors, precision low
temperature measurement and
control instrumentation, and
magnetic measurement and test
systems. Since 1968, Lake Shore
physicists, material scientists, and
engineers have dedicated
themselves to the development of
tomorrow’s technology today. Lake
Shore serves a worldwide network
of Customers including university
and national laboratories,
aerospace and other industries, as
well as many of the premier
companies around the world.