Lake Shore 520 User manual

User’s Manual
Cryogenic Temperature
Indicator/Controller
Model 520
ObsoleteNotice:
This manual describes an obsolete Lake Shore product. This manual is a copy from our
archives and may not exactlymatchyour instrument.Lake Shore assumesno responsibilityfor
this manual matching your exact hardware revision or operationalprocedures. Lake Shore is
not responsiblefor any repairs made to the instrumentbased on informationfrom this manual.
LakeShoreCryotronics,Inc.
575 McCorkleBlvd.
Westerville, Ohio
43082-8888 USA
E-MailAddresses:
[email protected]
[email protected]
Visit OurWebsite:
www.lakeshore.com
Fax:
[phone]
Telephone: [phone]
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 connectionwith furnishing, performance, or use of this material.
ObsoleteManual
October 1983

Table of Contents
Section Page
I. General Information
1.1 Introduction 1
1.2 Description and Applications 1
1.3 General Specifications 2
1.4
Major Assemblies Supplied 3
1.5 Options and Accessories Available 4
1.6 Temperature Sensors 4
1.7 Repacking for Shipment 5
11. Introduction
2.1 Introduction
7
2.2 Initial Inspection 7
2.3 Power Requirements 7
2.4 Grounding Requirements 8
2.4.1 Instrument Grounding 8
2.4.2 Temperature Sensor Grounding 8
2.5 Instrument Installation 8
2.5.1 Bench Use 8
2.5.2 Rack Mounting 8
2.6 Sensor and Heater Connections 8
2.6.1 Sensor Input Connections 8
2.6.2 Heater Connections 9
111. Operating Instructions
3.1 Introduction 11
3.2 Controls, Indicators and Connectors 11
3.3 Initial Checks 15
3.4 Temperature Readout Mode
15
3.5 Constant Temperature Control Mode 16
3.6 MAN and MIX Control Mode 17
3.7 Remote Parallel
BCD Input/Output Option 18
3.8 Grounding 18
IV. Theory of Operation
4.1 Introduction 21
4.2 General Description 21
4.3 Detailed Description 22
-ii-

Table of Contents, cont'd.
Section Page
V. Maintenance and Calibration
5.1 Introduction 27
5.2 General Maintenance 27
5.3
Access Information 27
5.3.1 Fuse Replacement 27
5.3.2 Model 5201
BCD Option Installation 28
5.4 Operational Checks 28
5.5 Calibration 29
5.5.1 Current Sources 29
5.5.2 Set Point
30
5.5.3 Diode Input Buffer 30
5.5.4 Resistor Input Amplifier 30
5.5.5
3X Current Summing 31
5.6 Troubleshooting 31
5.7 Replaceable Parts 32
5.7.1
How to Obtain Parts 33
-a-

Table of Illustrations
Reference
Des cr ip t ion Page
Figure
1.1 Model 520 Cryogenic Temperature vi
Controller
Figure 2.1 Model 520 Sensor Connection to 9
Table
2.1
Sensor Connections 9
Figure 2.2 Typical RM-3F and RM-5F Rack 10
Instrument
Mounting Installation
Controller Front Panel
Figure
3.1 Model 520 Cryogenic Temperature 14
Table
3.1 Functional Description of the 520 11
Front Panel and Rear Panel Features
Figure 3.2 Model 520 Cryogenic Temperature 14
Controller
Rear Panel
Table 3.2
Parallel BCD Output of Sensor 20
Voltage/Input of Set Point
Figure
3.3 Temperature Versus Time Characteristics 19
of Controller
Table 4.1 Translation
of Null Error Versus Set 25
Point Deviation
Figure 5.1 Component Layout
- A1 Main PCB 41
Table 5.1 Troubleshooting Guide for Model 520 34
Figure 5.2 Schematic
- A1 Main Schematics 43
Figure 5.3 Schematic
- A1 Output Section 45
Table 5.3 Parts
List - A2 Front Panel Assembly 49
Figure 5.4 Schematic
- A1 Power Supply 47
Figure 5.5 Component Layout
- Model 5201 BCD 57
Table 5.2 Parts List - A1 Main PCB Assembly 36
Table 5.4 Parts
List - A3 Rear Panel Assembly 50
Option
PCB
Table 5.5 Parts List - A4 Transfer Assembly 51
Figure 3.6 Schematic Model 5201 BCD Option 59
Table 5.6 Parts
List - A5 Heater Current Heat 51
Sink Assembly
-iv-

Table of Illustrations, cont'd.
Reference Description Page
Table 5.7 Parts List
- SA11 Heater Current 52
Range Assembly
Table 5.8 Parts List
- A7 Final Assembly 53
Table 5.9 Parts List Model
5201 BCD Option 54
PCB Assembly
Manufacturers
Table 5.10 Cross Reference of Parts 61
-V-

Figure 1.1 Model 520 Cryogenic Temperature Controller
-vi-

SECTION I
General Information
1.1 Introduc t ion
This section contains a description of the Model
520 Thermo-
meter/Controller, its applications, general specifications, major
assemblies supplied and accessory equipment available.
1.2 Description and Applications
The Model
520 Cryogenic Temperature Thermometer/Controller is
housed in an aluminum case and is rack mountable with the
RM-5H rack
mount kit in a standard
19" relay panel. All connections are at the
rear
of the case with
all normal operating controls on the front panel.
The instrument is line operated from either
115 volt or 230 volt mains,
50 or 60 Hertz.
The controller has the performance features needed for use with
silicon or gallium-arsenide diodes, germanium, carbon-glass, platinum,
or other resistance thermometers,
or any sensor with a voltage response
less than four volts or a resistance of less than
40,000 ohms. The 520
is designed to accept a voltage signal or resistance equivalent signal
from a temperature sensitive transducer, compare this signal with an internal
set point voltage or resistance equivalent voltage, amplify and process
their difference (error signal), and drive an external heating element.
Sensor currents from
1 microampere to 3 milliamperes can be
selected from the front panel. Use of analog control means constant
and immediate correction for temperature changes. Ample range of gain,
reset, and rate have been designed into the
520 to assure fast response,
low offset error, and high stability.
The Gain control
of the Model 520 has 1X and 3X steps similar to
those for the current supply. As a result, loop gain of the system can
be kept constant even when sensor current must be changed
to avoid sensor
self-heating or because of low signal value.
A heater output current of up to one ampere is available to
drive up to a 25 ohm load. Smaller load resistances will reduce the
maximum power below
25 watts as will higher resistance loads due to the
voltage limiting of the power supply of the output stage. The maximum
heater current may
be set from 10 mA to 1 ampere in 1X and 3X steps
which enables output power to be varied in decade steps over five orders
of magnitude.
-1-

Manual control of the heater output current is available from
the front panel. Additionally, the user can manually add
a fixed
current to the controlled current. This manual offset often produces
improved control in relatively stable systems and applications since
all
the heater power is not contributed via Controller gain.
The 520 can be used to accurately measure temperature by being
operated in the open loop mode. The sensor
is nulled against the set-
point using the built-in meter, thus the set-point becomes a read-out
of the actual sensor signal, either voltage or resistance. Referral to
the V(T) or R(T) calibration table for the particular sensor yields the
actual temperature reading.
In the resistance mode, the
set point is directly in ohms, thus
the user
is freed from constant use of Ohms Law to read or control tempera-
tures. In the diode mode, the set-point
is calibrated in volts since
most diode temperature calibrations
are provided as voltage as a function
of temperature
at a constant current.
Multi-sensor inputs for the Model 520
are possible with the
accessory Model SW-10A Sensor Selector.
Up to 10 sensors can be
connected to the 520.
the
SW-10A.
Selection is made via front-panel pushbuttons on
1.3 General Specifications
The following specifications for the Model 520 Cryogenic Tempera-
ture Thermometer/Controller are applicable when used with cryogenic
thermometers.
Input:
Temperature Range:
1.4 to 380K with Lake Shore DT-500 Series Sensors;
0 to 4 volts for other diode sensors; 0-40 ohms to 0-40K ohms for
resistance sensors
(4 ranges, selected by Sensor Current selector).
Recommended Sensors: DT-500 Series silicon or TG-100 Series gallium-
arsenide diode sensors;
CGR-1 carbon-glass, GR-200 germanium, or PT-100
platinum resistance sensors. (Order sensors separately.) Calibration
required over appropriate temperature range to provide V(T) or R(T)
data. Resistors with either positive or negative temperature coefficients
can be utilized.
Sensor Input: Separate diode and resistor inputs. 4-terminal input for
each type. Can be connected in 2-wire configuration.
Sensor Excitation:
1, 3, 10, 30, 100, 300, 1000, and 3000 microamperes
(resistors) or
1, 10, 100, and 1000 microamperes (diodes) selected
from the front panel.
-2-

Temperature Control:
Set Point: Selected via 5 front-panel digital thumbwheel switches
from
00000 to 39999. Decimal point is automatically positioned de-
pending on sensor type and sensor current selected to indicate 0.0000
to 3.9999 volts, 00.000 to 39.999 ohms, 000.00 to 399.99 ohms, 0000.0
to 3999.9 ohms, or 00000 to 39999 ohms. Optional BCD control with
Interface.
Typical Controllability:
± 0.0005K for temperatures below 30K,
± 0.005K at higher temperatures with silicon diodes in a properly
designed system.
Control Modes: Automatic: Proportional (gain), integral (reset), and
derivative (rate) set from front-panel controls. Manual: 0 to 100%
of full output can be set from front-panel. Manual and Automatic modes
can be used simultaneously.
Heater Output: 0-25 watts into 25 ohm load or 0-10 watts into 10 ohm
load (rear-panel switch-selected).
Heater current can be limited at
10mA, 30mA, 100mA, 300mA, and 1A (approximate decade power increments).
Temperature Readout:
Method: Sensor voltage
is nulled against set-point equivalent voltage
using front-panel thumbwheels in MANual mode. Temperature
is deter-
mined from V(T) or R(T) tables (requires sensor calibrated over approp-
riate temperature range).
Accuracy:
± 100 microvolts 2 calibration error of Sensor.
Gener
a1 :
Dimensions, Weight: 432mm wide x 146mm high x 330mm deep (17 in. x
5-3/4 in. x 13 in.). Style L, full-rack package. Net weight 8 kg
(18 lbs.).
Power: 105-125 or 210-250
VAC (switch selected), 50 or 60 Hz, 50
watts.
1.4 Major Assemblies Supplied
The Model 520 Cryogenic Temperature Thermometer/Controller
includes
as standard equipment, in addition to the controller proper,
the following additional components:
A.
B. One 14-pin male connector (LSCI Stock #106-070)
and 12 pins
(8 required) (LSCI Stock #106-060).
Assembly
mates with J1 connector on Model 520
Rear Panel.
One Operating and Service Manual
-3-

1.5 Options and Accessories Available
Model 5201 Interface. Allows remote digital control of set-point
and provides
BCD output of Sensor voltage divided by two.
Model SW-10A. 10-Sensor Selector Switch. Pushbutton selection of
any one of up to
10 sensors. Dimensions: 216m wide x 102mm high
x 330mm deep (8% in. x 4 in. x 13 in.). Style L half-rack package.
Model
RM-3H. Rack mount kit to mount either one or two SW-10A in
standard
3½ in. rack space.
Model RH-5F. Rack
ears with handles to mount Model 520 in standard
5¼ in. rack space.
1.6 Temperature Sensors
Model DT-500 Silicon Diode Sensors. (Refer to Lake Shore Series
UT-500 Technical
Data for details.)
DT-500K DT-500P -GR
DT-500KL DT-500FP
DT-500K-TO5 DT-500P-GR Mini
DT-500KL-TO5 DT-500FP-HRC-6
DT -5 0 0P DT-500FP-HRC-
7
DT-500CU-36 DT-50 ODRC
DT-500-CU-DRC-36
Model TG-100
GaAs Sensors. (Refer to Lake Shore TG-100 Technical
Data for details.)
TG-100P
TG- 1 00FP
Model
CGR-1 Carbon Glass Resistor Sensors. (Refer to Lake Shore
CGR-1 Technical Data for details.)
CGR-1-500 CGR-1-2000
CGR-1-1000 CGR-1-3000
CGR-1-1500
Model GR-200 Germanium Resistor Sensors. (Refer to Lake Shore
GR-200 Technical
Data for details.)
GR-200A-30,50,100,250,500
GR-200A-1000,1500,2500,5000
GR-200B-500,1000,1500,2500,5000
-4-

Model PT-100 Platinum Resistance Sensors. (Refer to Lake Shore
PT-100 Technical Data for details.)
PT-101 PT-103
PT-102 PT-1001
Sensor Calibration. (Other ranges also available.)
Type Range-K Type Range-K
0.05A.......0.05-6.0 1.4F 1.4-300
0.1A 0.1 -6.0 1.4G 1.4-380
4B 4.0-40
0.3A 0.3 -6.0
1.4A 1.4 -6.0 4F 4.0-300
4G 4.0-380
1.4B 1.4 -40
1.7 Repacking for Shipment
If the 520 appears
to be operating incorrectly, please discuss
the problem with a factory representative before returning the instru-
ment.
He may be able to suggest several field tests which could avoid
the unnecessary returning of a satisfactory instrument to the factory
when the malfunction
is elsewhere. If these tests determine that the
fault is in the instrument, the representative will provide shipping
and labeling instructions for returning it. In order to expedite the
repair of the instrument, contact the factory for a Returned Goods
Authorization (RGA) number. Include the instrument's model and serial
numbers in all written correspondence.
When returning an instrument, please attach a tag securely to
A. Owner and Address
B. Instrument Model and Serial Numbers
C. Malfunction Symptoms
D. Description of External Connections and
E. Returned Goods Authorization Number
If the original carton is available, repack the instrument in
the instrument itself (not on the shipping carton) clearly stating:
Cryostats
a plastic bag, place it in the carton using original spacers to protect
protruding controls.
Affix shipping labels and "FRAGILE" warnings.
Seal the carton with strong paper or nylon tape.
If the original carton is not available, pack the instrument
similar to the above procedure, being careful to use spacers or suit-
able packing material on
all sides of the instrument.
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This Page Intentionally Left Blank
-6-

SECTION II
Installation
2.1 Introduction
This section of the manual contains the necessary information
and instructions for installation of the Model
520 Cryogenic Tempera-
ture Thermometer/Controller. Included
are the initial inspection
procedures, power requirements, recommended grounding connections,
interface connector diagrams along with pin designations, and recom-
mended temperature sensor connections.
2.2 Initial Inspection
This instrument
was carefully inspected both mechanically and
electrically before shipment.
It should be free of mars or scratches
and in perfect
electrical order upon receipt. Immediately upon receipt
the instrument should be inspected for any damage that may have occurred
in transit.
If the shipment container or cushioning material is damaged,
it should be kept until the contents of the shipment have been checked
for completeness and the instrument has been mechanically and
electric-
ally checked. Procedures for checking the electrical performance of the
520 are given in Section V. If there is mechanical damage or the instru-
ment does not perform electrically, notify
LSCI immediately. If the
shipping container
is damaged or the cushioning material shows signs of
stress, be sure to file appropriate claims with the carrier and/or
insurance company, and notify LSCI of
the claims filing. Save the ship-
ping
materials for inspection by the carrier.
Be sure to inventory all components supplied before discarding
any shipping
material. In case of part(s) shortages, please advise LSCI.
The standard LSCI warranty as given in the front of this manual is appli-
cable to the Model
520.
2.3
Power Requirements
Before connecting the power cable to line voltage, verify that the
instrument
is set for the proper line voltage and fused accordingly. The
line voltage and fuse data
are shown on the rear panel of the instrument,
adjacent to the fuse holder.
The line voltage can be changed by switching line selector switch
S2, located on the rear panel (Figure 3.2, Key No. 17, Page 14).
Nominal permissible line voltage fluctuation is ± 10% at 50 to
60 Hertz.
-7-

2.4 Grounding Requirements
2.4.1 Instrument Grounding
To protect operating personnel, the National Electrical Manu-
facturer's Association (NEMA) recommends, and some local codes require,
instrument panels and cabinets to be grounded. This instrument is
equipped with a three-conductor power cable which, when plugged into an
appropriate receptacle, grounds the instrument.
2.4.2 Temperature Sensor Grounding
Refer to Figure 2.1 for illustrated individual sensor wiring
configurations recommended for optimizing system performance.
2.5 Instrument Installation
2.5.1 Bench Use
The Model 520 is shipped with
feet and a tilt ball installed
and is ready for use as a bench instrument. As with any precision
instrument, the 520 should not be subjected to excessive shock and
vibrations, such as the kind that usually accompany high vacuum
pumping systems.
2.5.2 Rack Mounting
The Model 520 can be installed in a standard 19" instrument rack
A typical rack mount
by using the optional rack mounting kit RM-5H. The basic hardware
and front handles are contained in the RM-5H kit.
installation is shown in Figure 2.2.
2.6 Sensor and Heater Connections
2.6.1 Sensor Input Connections
The 520 is supplied with a 14-pin male connector
LSCI Stock
#106-070) and 12 pins
(4 spares) (LSCI Stock #106-060) which mate with
connector
J1 on the rear panel (Figure 3.2, Key No. 27, page 14). This
connector interfaces both a resistance thermometer and a diode thermo-
meter
to the Model 520 Thermometer/Controller. Table 2.1 lists the pin
assignments for the connector. Figure 2.1 shows the sensor connections
for both the diode and resistance thermometers. The recommended cable
diagrams for the sensor diode and resistance thermometer are given in
Figure 2.1. The use of
a four wire diode connection is highly recommended
to avoid introducing lead IR drops in the voltage sensing pair which
is translated into a temperature measurement error or a control offset
from setpoint temperature. The alternate wiring scheme shown in Figure
2.1
(....) may be used for the diode, in less critical applications where
control is important, but small temperature offsets can be tolerated.
-8-

2.6.2 Heater Connections
The power output stage
is a current drive with a maximum current
available
of one ampere. The voltage supply for the current drive can
be selected to have an output of
10 volts on a low setting or 25 volts
on
a high setting (Figure 3.2, Key No. 22, Page 14); therefore, if your
heater resistance
is ten ohms or less, the low resistance setting should
be used
so as to minimize power dissipation within the instrument. The
maximum power deliverable to the load
is therefore equal to the load
resistance
as long as the resistance does not exceed 25 ohms for loads
greater than
25 ohms, the minimum power to the load is (25)2/R where R
is your load resistance and it is assumed that the lead resistance to
the heating element
is negligible.
The Heating element should be floated to preclude the possibility
of any of the heater current being coupled into the thermometer sensor
leads. Electrical feedback in addition to the desired thermal feedback,
may cause oscillations and certainly
will cause erroneous temperature
readings.
Inspect the heater element fuse FU2, (Figure 3.2, Key
No. 21,
Page
14) for proper value (3AG, 1.0A, Fast Blow, or smaller current
rating if desired). This fuse should not
blow under most circumstances
since the output stage
is a current stage with an upper limit of one
ampere rather than
a voltage stage with maximum current depending on
output
resistance.
Table 2.1
Sensor Connections
J1
Pin
Assignments
1
2
3
7
8
12
13
14
+I
+V
-V
-I
+I
+V
-V
-I
Diode
Diode
Diode
Diode
Resist or
Res is t or
Resistor
Resistor
Figure 2.1
-9-

Figure 2.2 Typical RM-3F & RM-5F Rack Mounting Installation
-10-

SECTION III
Operating Instructions
3.1 Introduction
This section contains
a description of the operating controls and
their adjustments under normal operating conditions. These instructions
are predicated upon the instrument having been installed as outlined in
Section
II. The diode polarity as shown in Figure 2.1 in particular must
be correct.
A diode sensor and/or a resistance thermometer is assumed to
be connected,
as shown in Figure 2.1. In addition, a resistive heating
element
is assumed to have been connected to the “Heater” terminals
(Figure 3.2, Key No. 23).
3.2 Controls, Indicators and Connectors
The operating controls, indicators and connectors on the instru-
ment's front and
rear panels are shown in Figures 3.1 and 3.2.
with
leaders to various controls in the figures are keyed to the entries
in Table
3.1.
The numbers
No. Key
1
2
3
4
5
Name
SET POINT - VOLTS
SET POINT
- OHMS
0-39.999, 399.99,
3999.9, or 39999.
Sensor Voltage
Alert
Volts LED
Ohms decimal LED's
GAIN
Function
Digital
set point of sensor
voltage
Digital
set point of sensor
resistance
LED turns on in the resistance mode
when the voltage
limit has been
exceeded. Fully counterclockwise
is
approximately 1 mV; fully clockwise
is approximately 40 mV.
LEI) turns on to indicate decimal
point when in the diode mode
(Key No.
14).
LEI) which is on depends on the Sensor
Current
selected (Key No. 16) and
indicates
decimal point and maximum
range
of set point resistance.
Gain Multiplier,
x1, x3, x10, x30,
and x100.
-11-

No. Key
6
7
8
9
10
11
12
13
14
Name
GAIN
Control Mode
Heater Current
Control
Reset
Rate
POWER
HTR CURRENT RANGE
MILLIAMPERES
HEATER CURRENT
Diode
- Res (-)
Res (+)
Function
Variable gain
1-10. Together with
gain multiplier, allows adjustment
of overall controller gain over
1000
to 1 range.
MAN position permits user to control
the current to the heater with the
heater current knob (Key No.
8).
AUTO uses controller to set output
power to force error signal to zero.
MIX allows both a manual output com-
ponent as well as an error component
of output power.
Sets the amount of manual heater cur-
rent when the Control Mode is either
MAN or MIX.
Adjusts auto-reset time constant of
integrator. Effectively determines
time constant
of integrator between
100 and 1 seconds, "MIN" and "MAX"
respectively, or "OFF".
Adjusts auto-rate time constant of
differentiator. Effectively sets
differentiator time constant between
1 and 100 Seconds, "MIN" and "MAX"
respectively , or "OFF".
A.C. line switch (ON/OFF) and pilot
light.
Switch selected current selector. Use
of a low setting will avoid inadvertent
boil-off in setting up system, and/or
system oscillations.
Monitors heater element current. Full
scale deflection corresponds to HTR
CURRENT RANGE switch (Key No.
12)
setting .
Switch for selecting diode temperature
sensor or resistive temperature sensors
with either positive
(+) or negative
(-) temperature coefficient for their
R vs. T curves.
-12-

Key No.
15
16
17
18
19
20
21
22
23
24
25
26
27
Name
NULL SENSOR
VOLTAGE
SENSOR CURRENT
MICROMERES
115
- 230 VAC
.4 - .75A SB
NO LABEL
RESISTANCE
HIGH
- LOW
1AMP
GND
HEATER
HIGH
- LOW
NO LABEL
NO LABEL
52
J1
Function
Indicates the difference between the
set point voltage and the sensor output
voltage. Meter is non-linear for large
errors of either sign. See page
and for discussion.
Selector switch for determining the level
of dc current for the temperature sensor.
10uA is recommended for diode sensors.
A.C. line voltage selector slide switch
(50-60 Hz)
.
A.C. line fuse (FU1). 115 VAC - 0.75
AMP., 230 VAC - 0.4 AMP.
A.C. line cord.
Selector switch to match load resistance
to controller output stage. HIGH is for
a load greater than
10 ohms, 25 ohms
optimum. LOW is for a load of
10 ohms
or less,
10 ohms optimum.
Heater element line fuse,
1 AMP
Fast Blow
Chassis ground terminal
Heater element lead terminals (Grey is
the HIGH side and black is the LOW
side)
.
Heat sink for output transistor.
Potentiometer used for setting the
resistive sensor voltage limit.
(See Key No. 2.)
40 pin connector for "REMOTE" BCD
in/out option
Sensor cable receptacle
(14 pin, LSCI
#106-142). See Table 2.1 for
sensor(s) connections.
-13-

Figure 3.1 Model 520 Cryogenic Temperature Controller Front Panel
Figure 3.2 Model 520 Cryogenic Temperature Controller Rear Panel
-14-