Lakeshore DRC-84C User Manual

User’s Manual

Model

DRC-84C

Digital Cryogenic

ThermometerlControlIer

Obsolete Notice:

This manual describes an obsolete Lake Shore product. This manual is a copy from our
archives and may not exactly match your instrument. Lake Shore assumes no responsibility for
this manual matching your exact hardware revision or operational procedures. Lake Shore is
not responsible for any repairs made to the instrument based on information from this manual.

Lake Shore Cryotronics, Inc.

575

McCorkle Blvd.

Westerville, Ohio 43082-8888 USA
E-Mail Addresses:

[e-mail]
[e-mail]

Visit Our Website:

www.Iakeshore.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
existing or applied for. Lake Shore Cryotronics, Inc. reserves the right
modifications,
consequential damages in connection with furnishing, performance, or use

Obsolete

or

products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or

Manual

to

add, improve, modify, or withdraw functions, design

of

this material.

to

U.S.

April

Patents

1982

Table

of

Contents

Section

I.

General Information

1.1

1.2 Description

1.3 Major Assemblies Supplied

1.4 Ordering of Replacement or Additional Sensors

II.

Ins tallation

2.1 Introduction

2.2

2.3 Power Requirements

2.4 Grounding Requirements

2.5 Installation

2.6 Repackaging for Shipment

III.

Operating Instructions

3.1

3.2 Controls, Indicators, Connectors

3.3 Temperature Readout

3.4 Analog Control

3.5 Analog Output of Temperature

3.6 Standard DT-500-DRC and DT-500CU-DRC-36 Curves

3.7

3.8

3.9

3.9.1 General

3.9.2 Specific Operation

3.9.3 Sample Programming

3.10

3.11

3.12 Rack Mounting the DRC-84C

3.13 Error Conditions

Introduction

Initial Inspection

Introduction

The 10-Sensor Selector Switch
Remote Parallel

IEEE

Installation of
Installation

Interface Option

IEEE

BCD

Input/Output Option

Specifications and Operation

of

the DRC8-IEEE Interface

DRC

of

DRC

BCD/L-A

IEEE

Option Board

Option Board

Page

1
1

3

3

5

5

5
5

5

6

9
9

12

12
13

13

13
14
26
26
27
32
34
35
36
36

-ii-

IV.

Theory

4.1 Introduction

4.2 General Description

4.3 Detailed Description

4.3.1 Power Supplies

4.3.2

4.3.3

4.3.4 Software

4.3.5

4.3.6 Digital Display Board

of

Operation

Precision Current Sources and Input Switching

A/D

Converter and Microprocessor Hardware

Analog Control and Set Point

37

37

39
39
40

40
41
44
45

Table

of

Contents (cont'd.)

Section

V.

VI.

Calibration and Troubleshooting

5.1

5.2

5.3 General Remarks

5.4 Instrument Calibration

5.4.1 Current Sources

5.4.2

5.4.3

5.4.4 Output Buffer

5.4.5

5.5

Replaceable Parts

6.1

6.2 DRC-84C

Introduction
Test

Equipment

A/D

Converter

D/A

Converter

DRC

L/A

Instrument

Main

Board Components

Option

Tests

List

BCD-L/A

(if

and

present)

IEEE

Components

List

Page

47

47

47
47
47
48
48

51

51

55

55

63

-iii-

Table of Illustrations

Reference

Figure

Figure 2.1
Table 3.1
Figure
Figure 3.2

Table 3.2

Table 3.3
Figure
Table 3.4
Figure 3.4

Table 3.5
Table 3.6

Table 3.7
Figure 4.1
Figure 4.2

Table 5.1
Table 5.2
Table 5.3
Table 5.4

1.1

3.1

3.3

Description

Model DRC-84C Digital Cryogenic

Thermometer/Controller
Sensor, Cable, and Monitor Connections
Entry Number Correlation

DRC-84C Front Panel
DRC-84C Back Panel

BCD

Relative Gain for

Reset

DRC-84C-IEEE Panel Layout
DT-500-DRC Voltage-Temperature Characteristic
Model DRC-84C showing Rack Mount

SW-1OA Connector

BCD

DIN

DRC-84C Block Diagram
Software Flow Diagram

Decimal-hex Table

Data

DRC-84C Troubleshooting Notes
DRC-84C Troubleshooting Notes

Time

Constants for

Detail

Temperature Output - Model DRC-Series

Remote

Standard Curve for Platinum Sensors

1/0

for Standard Curves (D

Option

BCD

Option

&

E)

Kit

Page

7
9

11

11

15
16
28

17

35

20

21

22
38

43

49
49
52
53

Figure 6.1
Figure 6.2

Figure 6.3
Figure 6.4
Figure 6.5

Figure 6.6
Figure 6.7
Figure 6.8
Figure 6.9
Figure
Figure 6.11

6.10

DRC-84C Power Supply
DRC-84C Current Source, Input Connections,

Switching
DRC-84C
DRC-84C Analog Output Section
DRC-84C Component Layout

DRC-84C Display Board
DRC-84C Display Board Component Layout
DRC-84C
DRC-84C
DRC-84C
DRC-84C

Microprocessor Section

BCD/L-A

BCD/L-A

IEEE

IEEE

Option

Option Component Layout
Option
Option Component Layout

67

69

71

73
75

77

77

79

79

81

81

-iv-

Specifications, DRC-84C Temperature Controller

Input: General:

Temperature Range:

diode DRC Sensor
30

to

800K with platinum sensor. Silicon diodes cannot Additional outputs listed below as options.

be exposed

Sensors (order separately):

DT-500CU-DRC-36 or any calibrated DT-500 Series package. Net weight 8.4 kg (18.5 Ibs).
Diode (with DRC-Precision Option). See below for

proper response curve. Platinum RTD: PT-101. PT-102, 75 watts,
PT-103'

See response curve details below.

Sensor Input:

platinum RTD). Front-panel switch selects either section.
Each section accommodates two sensors with 4-terminal
input for each sensor. Front-panel switches enable
independent selection of either sensor within each patible. Allows remote control of set-point, gain,
section as display and/or control sensor. Display/control reset, and provides BCD
sensors cannot be mixed between silicon and platinum and Sensor selected (either from front-panel or optional
sections. SW-10A)

Sensor Excitation:

for each sensor in silicon-diode section,
(±0.005%) for each sensor in platinum RTD section. temperature in Kelvin and Sensor selected (either from

Sensor Response Curves:

tic US units require Sensor Curve "D". Export units
require Sensor Curve
change, refer
ing Sensors. Curves
on special request. See also DRC-Precision Option. except for use when unit is also equipped with
Platinum RTD Section: Standard response curve is
based on 0.1% interchangeability at 0°C and temp­erature coefficient (0-100°C)

to

Lake Shore PT-100 Technical Data for details.
Special calibrations are available and may be incor­porated into the 84C via the DRC-Precision Option.

Input Resistance:

mum Sensor Power Dissipation: Silicon-diode: 25µW

at 4.2K. Platinum: 25µW below 80K increasing

at 273K.

Temperature Readout:
Display:

directly in Kelvin or Celsius as selected by front-panel
switch. Display Sensor can be selected independent of

Control Sensor within each section.

Resolution:

resolution to 0.01 K for temperatures below 30K and

0.05K for 30-100K (no increase in accuracy).

Accuracy (20-25°C ambient):

4K and 77K. ±1.0K at 300K with standard sensor. calibration range. Any DT-500 Series Silicon Diode
Accuracy with Lake Shore calibrated Sensor and DRC- Sensor or PT-100 Series Platinum RTD can be utilized.
Precision ±0.1 K or better depending on calibration Requires that an appropriate calibration be purchased
range. Platinum RTD: Conforms

±0.1K. See Lake Shore PT-100 Technical Data for 1-10 on SW-10A)

details. Calibrated Sensor and DRC-Precision improves within PROM.
accuracy to ±0.01K depending on range. First calibration stored

Temperature Control: Model DT-500-DRC.
Set-Point:

Kelvin,
Panel switch. Remotely settable in Kelvin with BCD

or IEEE-488 Option. Sensor (8mm diameter

Set-Point Resolution:
Typical Controllability:

designed system. long).

Control Mode:

Set via front panel or remotely with BCD or IEEE-488 long).
option.

Heater Output:

LO: 0-10 watts nominal (1A max or 12V rnax). Isolated
Output. 25-ohm heater is recommended.

Control Sensor:

independent of Display Sensor within either section.

to

Or

any

4 digit, 1.1 cm (0.43") LED shows temperature

0.1K or 0.1°C. "Scale Expand" increases 3½" rack

Digital thumbwheel selection directly in (1.5mm diameter X 4.1mm long). Specify response

(+)

Celsius, or

1.4

to

(to

temperatures above their useful

Other

Two section input (silicon-diode and

330K with standard silicon

380K with other silicon Sensors). voltage (silicon) and5X Display Sensorvoltage (platinum).

range.

Silicon Diode: DT-500-DRC.

100-ohm, 0.00385/°c

Sensor'

Monltor Output:

Dimensions,

330mm deep

power:

90-110, 105-125, or 210-250VAC.

Accessories Supplied:

inputs and monitors, instruction manual.

Options and Accessories Available:
Model DRC8-BCD.

Buffered output of 1X Display Sensor

Weight:

432mm wide x 102mm high x

(17 in

x

4 in x 13 in). Style L. full-rack

Mating connectors for sensor

Parallel BCD interface, TTL com-

output

.

Current source. 10, microamperes

Silicon Diode Section: Domes-

"E".

to

manual for proper curve when reorder- 10mV/K at<10 ohm output resistance.

Greater than 1000 megohms. Maxi-

Proportional (gain) and integral (reset).

HI:

Selected by front-panel pushbutton

Sensor curves subject

to

match existing Sensors available

Silicon-diode: ±0.5K at specified accuracy

to

(-)

Celsius as determined by front-

0.1K or 0.1°C.

0.1K or better in a properly

0-25 watts (1A max. 25V max). long).

0.5

milliampere of set-point, gain, reset and provides digital output of

of

O.O0385/"C. Refer

to

100µW

DIN 43760 tolerances for the Sensor. Specify Sensor input position (A or B or

Model DRC8-IEEE.

front-panel or optional SW-10A)

Model DRC8-L/A.

to

temperature for use with recorders, or other readouts.

Model KT-LA.

488 interface. Allows remote control

Analog output proportional

Analog output identical

BCD,

Model KT-BCD.

DRC8-BCD

with

DRC8-L/A,

Model SW-10A.

DRC Thermometer or Controller. Pushbutton selection

of

any

one

position. Sensor selected

interfaces.

x

330mm deep (8% in x 4 in x 13 in). Style L half-

rack package.

Model RM-3F.

L

full-rack instrument package in standard 3%" rack

space

Model

RM-3H.

either one of two Style L half-rack unit(s) in standard

DRC-Precision Option:

only-memory for DRC instruments which improves

space,

Parallel

except

10-Sensor Selector Switch for use with

of

up

to

Dimensions: 216mm

Rack ears with handles

Rack

to

BCD

for

use

when

10

sensors,

is

mounting

Custom-programmed

to

±0.1K or better over a given

assure proper location

.

Subsequent Calibrations stored in same PROM.

Silicon Diode Temperature Sensor

curve

.

Model DT-500CU-DRC-36.

hole). Specify response curve

Model PT-101.

Model

Model PT-103.

Platinum RTD (3.lrnm diameter x 30.5

PT-102.

PIatinurn

Platinum RTD

Specifications subject

Silicon Diode Temperature

x

3.3mm thick with mounting

RTD

(2.0mm diameter x 20.3rnrn

(1.8mm

50

or 60Hz.

of temperature in Kelvin

.

to

Kelvin

to

DRC8-L/A

DRC8-

interface

unit

Connects

also identified via digital

wide

hardware

.

to

change.

identical

is

also

equipped

to

Sensor

"B"

x

102mm

high

to

mount style

to

mount

read-

of

calibration

rnrn

diameter x 12.1mm

to

-V-

-vi-

FIGURE

1.1

Model DRC-84C Digital Cryogenic Thermometer/Controller

SECTION

I

General Information

1.1

Introduction

The following is a description of the DRC-84C Cryogenic Digital
Thermometer/Controller. The DRC-80 Series of instruments is designed to be
used with the Model DT-500-DRC and DT-500CU-DRC-36 silicon diode sensors

manufactured by Lake Shore Cryotronics, Inc.

Several different diode sensor curves are designed for use with this
instrument. When ordering replacement sensors, care must be taken to assure
that the correct sensor curve is specified. Multiple curves are needed
that Lake Shore can assure the customer that replacement sensors

will

so

be

available at any time in the future. For details, please see Section 1.4.

This controller

will

also use the PT-101,

102,

103 Series of platinum

resistance thermometers which are available from Lake Shore Cryotronics,

Inc. The data sheet for these sensors is included in the back of this manual.

1.2 Description

The DRC-80 Series is comprised of completely self-contained units
providing direct digital readout in Kelvin temperature units and, for the
controllers, temperature control by direct analog comparison between the
sensor voltage and an analog equivalent of the digital temperature set point.

The Lake Shore DRC-84C utilizes two temperature sensor technologies to
achieve its wide range: Silicon diodes for the low range (1.4-330K), and

platinum RTD's for higher temperatures (30-800K). Each sensor type has its

own input section which contains appropriate sensor excitation sources,
signal conditioning, and switching.

A

microprocessor

in

the 84C determines
the temperature based on the input section activated, the sensor signal, and
the sensor-response curve stored in internal memory. Additionally, the micro-

processor generates a voltage equivalent to the control set-point temperature

for the sensor in use. Comparison of that voltage with the actual sensor

voltage produces the error signal which is the basis

of

the 84C's analog

control.

Each input section of the DRC-84C features dual-sensor input which

enables two sensors to be used concurrently. Either sensor can be selected

to be the control sensor and/or the temperature display sensor (both sensors

must be of the same type
can be centered at one point

-

silicon diodes or platinum RTD's). Thus control

in

a system and temperature monitored elsewhere.
This permits, for instance, maintenance of temperature at a particular cold
stage and simultaneous measurement of sample temperature. Selection of input
section as well as display and control sensor is made via front-panel push-

but tons.

-1-

A 4-digit display clearly and unambiguously shows the temperature

directly in Kelvin or Celsius with 0.1 degree resolution. At low temperatures

(under 30K) a SCALE EXPAND mode increases resolution to 0.01K for monitoring
trends and other relative temperature measurements. Absolute accuracy at
low temperatures is ±0.5K in either mode.

The silicon-diode input section of the DRC-84C is designed to use proven

Lake Shore DT-500 Series DRC-curve silicon-diode Sensors, which provide

measurement accuracy to ±0.5K at low temperatures. Accuracy can be increased

to better than ±0.1K through use of an individually calibrated sensor and
the DRC-Precision option to store the calibration. Any DT-500 Sensor can
be utilized in the latter case.

Lake Shore PT-100 Series 100-ohm Platinum RTD's are the ideal Sensors
for the platinum section. The standard response curve is based on 0.1%
interchangeability at

0.00835/°C.

The curve conforms to DIN standard 43760 and is published in

°

0

C and a temperature coefficient

(0

to 100°C) of

the Lake Shore PT-100 Technical Data sheet. Custom calibrations are avail­able and can be incorporated into the 84C via the DRC-Precision option.

Since silicon-diode sensors can be damaged by exposure to temperatures

above 380K (DT-500DRC Sensors should not be used above 330K to prevent deter­ioration of their epoxy seals), precautions are recommended in designing
systems for operation at higher temperatures. The preferred approach is to

have diode sensors installed only when the system is operated below room

temperature. Special software limits and error codes are generated if the
instrument is set to control a point above or below the silicon diode or
platinum sensor temperature limits (see Section 3.13

-

Table of Error Condi-

tions).

Control temperature is easily selected and read directly in Kelvin
or Celsius on front-panel digital thumbwheel switches and an adjoining scale­select switch. The switches provide quick and constant display of the set

point with a resolution of 0.1K or C. Temperature controllability is a

function of system design; and performance is often better than

°

0.1

degree.

Both the gain and reset are variable, and can be set from the front
panel to enable the Controller to be precisely tuned to match the system
response over any temperature region. Ample gain and reset have been

designed in to assure fast response, low offset error, and high stability.

Two heater output levels are selectable on the DRC-84C.

Th

HI

mode

provides up to 25 watts of heater power while the LO mode limits output power

to a nominal 10 watts.

Five options are available with the DRC-80 Series of instruments. One
option

is

an analog signal which is proportional to temperature (DRC8-L/A).

This option has a sensitivity of 10 mV/K.

A second option is a ten-position switch (SW-10A) for multiple sensor

readout. This switch is a separate half-rack box which plugs into the Sensor
"B" position of the DRC-84C. The sensor selected is also identified via

digital interface of the DRC-84C, if present.

-2-

Another option

corresponds to the calibration curve of the customer's DT-500 Series sensor.

A

combination of a calibration and custom cut PROM

accuracy to nearly

any sensor may be used with this option,

stricted to the

DRC

is

a

custom cut PROM (DRC-Precision Option) which

will

±.1

Kelvin over the calibrated range. Please note that

i.e.,

Series sensors.

the customer

increase display

is

not

re-

There
set-point, the gain and
and sensor selected from the

format while the

The DRC-80 Series
ciated support circuits. The
up to 32 break points per curve. The data consists of
and voltage associated with each break point.
can generate the
entire temperature range

±0.5K

1.3

thermometer-controller, the following:

at

Major Assemblies Supplied

The DRC-84C includes

A.

B.

C.

are

two programming options available; each

reset

DRC8-IEEE

is

DRC

curve to an accuracy of better than

Helium and Nitrogen temperatures and to

Operating and Servicing Manual

Four five Pin Plugs for Temperature Sensor Cables

One seven Pin Plug for Monitor of Sensor Output Voltage

and the

DRC8-L/A

as

well

SW-10A.

is

in the popular IEEE-488 format.

designed around a 3870 microprocessor and asso-

DRC

(4.0

-

400K). The

as

The

curve

output the displayed temperature

DRC8-BCD-I/O

is

stored in a PROM which can handle

These straight line segments

DRC

diodes match this curve to

±1.0K

as

standard equipment, in addition to the digital

option

will

is

a

at

control the

in a parallel

table of temperature

0.1

Kelvin over the

room temperature.

BCD

Model DT-500 Series silicon diodes or platinum thermometers

as

supplied

Complete Specifications, Accessory Equipment and Customs Options
listed in the front of the Manual.

1.4 Ordering of Replacement or Additional Sensors

Two

Model
DRC-36 sensors. Their description

sensor configurations

PROM

Series instruments.
instrument, you must be certain to order the correct curve

DRC-80

is

More than one

part of the

different sensor configurations

Series instruments. These

cut.

DRC-84C

are

available if the diode

curve presently

If

additional sensors

instrument.

are

available for use with the

are

the DT-500-DRC and the DT-500CU-

is

included elsewhere in this manual.

is

calibrated and a special

exists

which can be used with the DRC-80

are

ordered for use with your

so

that your

are

not

are

All

-3-

instrument will have its stated accuracy. The proper curve may be determined
in one of the following ways:

A.

Specify the sensor serial number that is currently being used
with the instrument (serial number is found on the end of the
plastic box in which the sensor was received).

B.

Specify the serial number of your instrument. Our records

will

indicate with which sensor the instrument is compatible.

C.

Remove the top of your instrument and observe the indicator

on

the

curve PROM.

D. The fourth way is to measure the diode voltage at

give this value to Lake Shore Cryotronics, Inc. when re-

ordering sensors.

Lake Shore PT-100-ohm Platinum RTD’s are available for the platinum
section. These thermometers have a
temperature coefficient

(0

to 100°C) of

0.1%

interchangeability at 0 C and a

0.00385/°C.

4.2K

and

°

-4-

SECTION II

Installation

2.1 Introduction

This section contains information and instructions necessary for the
installation and shipping of the model DRC-84C Cryogenic Temperature Indicator

and Controller. Included are initial inspection instructions, power and
grounding requirements, installation information and instructions for repack­aging for shipment.

2.2 Initial Inspection

This instrument was electrically and mechanically inspected prior to
shipment. It should be free from mechanical damages, and in perfect working

order upon receipt. To confirm this, the instrument should be inspected visual-

ly for obvious damage upon receipt and tested electrically by use to detect any

concealed damage. Be sure to inventory all components supplied before dis­carding any shipping materials. If there is damage to the instrument in tran-

sit, be sure to file appropriate claims with the carrier, and/or insurance

company. Please advise the company
ages, please advise the company. The standard Lake Shore Cryotronics warranty

is given on the title page.

of

such filings. In case of parts' short-

2.3

ment is of the proper line voltage and fused accordingly. The line voltage and

fuse are shown on the rear panel of the instrument.

(S2

board of the unit.

2.4 Grounding Requirements

Association
and cabinets to be grounded. This instrument is equipped with a three­conductor power cable which, when plugged into an appropriate receptacle,
grounds the instrument.

2.5 Installation

generate significant heat. It may therefore be rack mounted in close proximity
to other equipment in dead air spaces. The heat from such adjacent equipment
should not subject the controller to an ambient temperature in excess of

Power Requirements

Before connecting the power cable to line voltage, insure that the instru-

The line voltage can be changed by switching line voltage selector switch

-

Figure

Nominal permissible line voltage fluctuation is

To protect operating personnel, the National Electrical Manufacturer's

The DRC-84C Thermometer/Controller is all solid state and does not

6.5

DRC-84C Component Layout) located on the main printed circuit

±10%

(NEMA)

at 50 to

recommends, and some local codes require, instrument panels

60

Hz.

-5-

50°C (122°F).

As

with any precision instrument,

it

should not be subjected
to the shock and vibrations which usually accompany high vacuum pumping
systems.

The recommended cable diagrams for the sensor diode and heater element

(in the case of the DRC-84C controllers) are shown in Figure 2.1 (a) and

(b).

The use of a four wire diode or resistor connections is highly recommended to

avoid introducing lead IR drops which
sensor cable connection is used. For example, for
diodes, every 25 ohms of cable resistance corresponds to a

Kelvin.

the diode

The alternate wiring scheme shown in Figure 2.1

in

less critical applications where lead resistance can be kept

will

occur if the alternate two lead

a

two lead connection with

.1K

error above

(c) may be used for

30

small. Because of the low resistance of platinum resistance thermometers, the
four lead cable connections must be used to obtain system accuracy. The indi-

cated shielding connections are the recommended standard practice to avoid
ground loops. Figure 2.1

output of sensor voltage (0-2.5V for diodes,
optional linear analog output of temperature

(d)

shows the monitor connections for the analog

0-3.0V

(0-BV,

for platinum, Pin

Pin C). In the case of

A)

and

the platinum resistor, the buffered output voltage is -20 times the actual
sensor voltage. For example, if the input voltage from the platinum sensor
is 0.0100V, then the buffered output voltage would be -0.2000V.

2.6 Repackaging for Shipment

Before returning an instrument to the factory, should repair be neces-

sary, please discuss the malfunction with a factory representative. He may be

able to suggest several field tests which will preclude returning a satisfac­tory instrument to the factory when the malfunction is elsewhere.

If

it

is

indicated that the fault is in the instrument after these tests, the represen-

tative will provide shipping and labeling instructions for returning

it.

When returning an instrument, please attach a tag securely to the

instrument itself (not on the shipping carton) clearly stating:

A. Owner and Address

B. Instrument Model and Serial Number

C. Malfunction Symptoms

D. Description of External Connections and Cryostats

If the original carton is available, repack the instrument in a
plastic bag, place in carton using original spacers to protect protruding
controls, and close carton. Seal lid with paper or nylon tape. Affix
mailing labels and "FRAGILE" warnings.

-6-

FIGURE.2.1

Sensor, Cable, and Monitor Connections

-7-

3.1 Introduction

SECTION III

Operating Instructions

This section contains a description
their adjustment under normal operating conditions, and typical controller
applications. These instructions are based upon the instrument having been

installed as outlined

2.1

(a),

in particular, must be correct. For the DRC-84C instrument, a 25

ohm heating element is assumed attached to the "Heater" terminals as shown

in Figure

3.2 Controls, Indicators, Connectors

instrument's front and rear panels are shown in Figures 3.1, and 3.2. The
numbers
entries in Table 3.1.

NO. KEY

1

2

2.1

(b).

The operating controls, indicators and connectors on the DRC-84C

with

leaders to various controls in the figures are keyed to the

NAME

POWER

NO LABEL

in

Section

Table 3.1

II.

-

Entry Number Correlation

FUNCTION

A.C. line switch (ON/OFF) (Display serves
as indicator light).

Digital set point. Has 0.1 K resolution.

of

the operating controls and

The diode polarity as shown in Figure

3

4

5

Gain

Reset

NO LABEL

Variable gain allows adjustment of overall
controller gain over

mum gain is full clockwise prior to detent

position labeled REM which transfers gain
control to remote BCD or IEEE option when
present. The potentiometer is logarithmic

so

that x10 gain is approximately one-half

of full rotation.

Adjusts reset time constant of integrator.
Effectively determines time constant of

integrator between 25 and
and maximum, respectively. Note that reset
control can be transferred to either the BCD
or IEEE options if one of them is present.

Digital temperature display located behind
filter panel. LED indicators also indicate
scale expand, which sensor is selected for
display, which sensor is selected for con­trol and type of sensor.

100

to 1 range. Maxi-

1

seconds, minimum

-9-

This

Page Intentionally Left Blank

6

Scale Expand

With button out, the display reads to
at all temperatures; with button in detent
position, temperature reads to

30K,

0.1K

on

0.05K between
above

display panel.

100K.

30K

and

Scale expand

0.01K

100K,

is

0.1K

below

and to

indicated

7

8

9

10

11

12

Sensor Display

Sensor Control

Type

Heater

HI

Scale

Power

With buttori out, sensor
displayed; with button in detent position,

sensor

being read
panel.

With button out, sensor

sensor; with button in detent position,
sensor
sensor

With button out, the silicon diode inputs

are

position, the platinum sensor inputs are
selected

With button out, heater power maximum

is

full heater power

watts).

Hi

Selects either the Celsius or Kelvin
scale for both the display and the
set-point.

B

is

read and displayed. Sensor

is

also indicated on display

B

is

the control sensor. Control

is

also indicated on display panel.

selectable; with button in detent

.

10

watts (LO); in detent position,

is

power

LED

indicator.

A

temperature

A

is

control

available

is

(25

-10-

13

14

15

16

17

NO

LABEL

Fuse

Diode Sensor
Inputs

Platinum Sensor
Inputs

Monitor

A.C.

A.C.

Diode

V-,

Same connections

Analog output of sensor voltage (0-2.5V,
pin

of

is

ground for linear analog output.

line cord.

line fuse.

Sensor A and B input lead terminals

(Pin

A,

I+,

Pin

E,

V+,

Pin

B,

Pin

H,

Shield).

as

for diode sensors.

A)

and optional linear analog output
temperature (0-4V, pin C). Pin
ground

for

sensor voltage, Pin

I-,

Pin

B

D

is

D,

FIGURE

3.1

DRC-84C Front Panel

FIGURE

3.2

DRC-84C

Back

Panel

-11-

18

Heater

Heater element terminals (25 ohm heater

25

required for

watts of power).

19

20

Fuse

Interface

Output power fuse

(1.0

ASB specified).

BCD input of set point, gain and reset
output of temperature. Also IEEE

interface port.

21

GND

Instrument or case ground

3.3 Temperature Readout

The sensor(s) and heater should be installed following the

suggestions listed

in

the "Installation and Application Notes for

Cryogenic Sensors" brochure in Section VIII.

Connect the sensor(s) to the instrument following the diagram in

Figure 2.1.

Depress the power switch and observe that the display shows the

proper temperature relative to the sample temperature.

If the diode or lead wires are shorted or if the diode is connected
backwards, the display
an open current or voltage lead, the display

will

read

(----)

and flash 428.0.

will

slowly drift higher in

In

the case of

temperature from the last voltage reading taken by the A/D converter.

The sensor and readout display for diodes should follow Table 3.4

which illustrates typical values expected of the standard DT-500-DRC or

DT-500CU-DRC-36sensors for your appropriate curve.

The DIN standard curve for the platinum sensors is given in Table 3.7.

If the instrument or sensor does not agree with values listed in the
table, within the accuracy of the system, consult sections on installation
and/or section on troubleshooting to determine the cause and cure of the

malfunction. If an error code is displayed, refer to Section 3.13 for

possible corrections.

3.4 Analog Control

The digital set point of temperature is converted to an analog set
point of voltage which is then compared to the sensor voltage by summing

two respective currents of opposite sign.

To familiarize yourself with the DRC-84C control section, set the

instrument

so

that you are reading and controlling with the same sensor.
Turn the reset (integral) control section off. Establish a set point
temperature several degrees above the display temperature. Gradually

turn the gain clockwise from a minimum position. Note that as the gain
is increased, the offset between the display temperature and the set point

-12-

will

be decreased. The gain potentiometer is logarithmic with rotation and

covers a

100

to 1 range

minimum gain.

so

that the gain at mid-rotation is ten times the

With most systems, an oscillation in temperature

clockwise rotation. Further clockwise rotation

will

will

occur at some

cause a wild oscilla­tion in temperature. The gain should then be backed off until a stable
control temperature occurs. Note that an offset between display tempera­ture and set point will still be present.

Finally, turn on the reset control. With the addition of reset, the

temperature error between setpoint and control temperature should reduce to

zero. The rate at which this reduces to zero is determined again by a
clockwise rotation with the shortest time constant occurring at full clock­wise rotation.

Note that the system can become unstable again with too much reset

added.

Slight variations in the gain and/or reset should give stable

temperature control.

The

HI-LO

tion increasing the gain by a factor of approximately two.
necessary when changing from

power switch also changes the loop gain with the

It

may be

LO

to

HI

power setting to reduce the gain

HI

posi-

slightly to compensate for the increased overall loop gain.

3.5 Analog Output of Temperature

The analog output of temperature takes the display temperature and

converts

it

to an analog signal which has a sensitivity

of

10 mV/K under
normal operation. The analog output voltage is located on the monitor
connector (Key

17

of

Figure 3.2). See Section 3.10 for installation notes

on DRC-8-L/A.

3.6 Standard DT-500-DRC and DT-500CU-DRC-36 Curves

The standard DT-500-DRC and DT-500CU-DRC-36 curve is explained in
Section 3.3. The Tables include a list of PROM sensor voltages and break­points used in the linearization

of

the DRC curve to arrive at the correct

temperature readout.

3.7 The 10-Sensor Selector Switch

The 10-Sensor Selector Switch includes an umbilical which ties to the
DRC-84C main printed circuit board (via a 16-pin ribbon cable header which
plugs into internal socket JC (see Figure 6.5, DRC-84C Component Layout)
and a cable to connect the selected sensor leads to the DRC-84C (Sensor
Plug

B

is either Key 15 or Key

16

of

Figure 3.2).

The SW-10A is supplied with an 18" cable which is shielded and has

male 5-pin amphenol connectors at each end. This cable connects between

-13-

J11 of the SW-10A and one of the B sensor plugs of the DRC-84C. Sensors
are connected to the SW-10A via printed circuit edge J10.

A

36-pin edge
card connector and hood has been supplied with the SW-10A. Connectors to
this edge J10 are given in Table 3.5.

3.8 Remote Parallel BCD Input/Output Option

The BCD option consists of a

along with a scale expand

bit

to indicate decimal point, a 15 bit parallel

16

bit

parallel output of temperature

input of set point in Kelvin degrees or Celsius (depending on switch posi­tion), a
reset setting, and a

4

bit parallel input of gain setting, a 4 bit parallel input of

4

bit output

of

switch position from the SW-10A.

Table 3.6 can be used for input and output line coding.

The BCD in and out is handled through connector

panel as INTERFACE), a

50

pin connector on the rear panel of the instrument.

Two internal jumper wires are placed on the printed circuit board

J4

(denoted on back

in

front

of internal connector JE. Cutting these jumpers allows the user to enable

the remote set point by setting Pin 38,

J4

high (see Table 3.6). If the
option was installed prior to shipment, these jumpers have already been cut.
Options that are field installed need to have their jumpers cut by the user.

Data latches internal to the instrument provide a 1-2-4-8 code using

positive logic with standard TTL levels of

0)

and 2.4 volts or higher for the high (or 1) state under full load con-

0.4

volts or less for low (logic

ditions. The drivers are sufficient to drive two standard loads, 3.2mA,

in

the low state.

Set point is input to the instrument via a remote set point enable

pin (externally generated,

pin

38). With no connection made to the external
enable pin, the option selects the internal (front panel) set point. When
the unit is receiving a set point externally, the front panel set

point switches are disabled.

-14-

The sensor temperature output

is

externally gated through the use of

an internally generated data valid pulse.

Input of gain value and reset can be seen

(highs are denoted as

"1"

and lows are denoted as

in

the following tables

"0").

Table

3.2

Relative Gain for

GAIN

Pin Pin Pin Pin

48 46

0

0

0

0

0

0

0

0

1

0

0

0

0

1

1

1 1

1

0

44 42

0

0

1

1 1

0

0

1

0

0

1

0

0

1

0

1

0

BCD

Option

Relative Gain"

Min.

2.

2.5

3.25

3.85

4.8

5.2

6.1

13.3

1

1

1

1

1

1

1

0

0

0

1

1

1 1

1 1

0

1

1

0

0

1

0

1

0

1

0

1

"The gain of the basic instrument is

potentiometer covering a

100:1

span. The relative gain is the gain

10

to

1000

with the front panel

14.2

14.5

15.4

15.8

16.65

17.2

Max.

factor above which the base instrument has incorporated. These
relative gains can be multiplied by about

These values were determined to make use

10

to get overall gain.

of

the range of gain most
used and the fact that the circuit is based on a negative logarithmic
variation

of

the front panel potentiometer.

-15-

This table can be shifted

up

or down in terms

customer needs to, but should not be necessary.

of

overall gain

if

the

The reset amplifier readings take on roughly the same sort

of

plot
as the gain with minimum reset value with all lines low and maximum reset
value with all lines high.

Table

3.3

Reset Time Constants for BCD Option

RESET:

Pin Pin Pin Pin

41

0

0

0

0

0

0

45

0

0

0

0

1

1

43

0

0

1

1

0

0

41

0

1

0

1

0

1

(sec)

Off (Open)

28

21

19

16

14

0

0

1

1

1

1

1

1

1

1

1

0

0 0

0

0

1

1

1

1 1

1

1

0

1

1

0 0

0

1

1

0

1

0

1

0

1

1

0

1

12

10

9

8

7

6

5

4

3

Min.

-16-

Table 3.4

DT-500DRC (D) Voltage-Temperature Characteristic

30

29

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.5

6.0

6.5

2.5984

2.5958

2.5932

2.5906

2.5880

2.5854

2.5828

2.5735

2.5643

2.5551

2.5458

2.5366

2.5226

2.5086

2.4946

2.4807

2.4667

2.4527

2.4387

2.4247

2.4108

2.3968

2.3618

2.3269

2.2919

28

27

26

25

7.0

7.5

8.0

8.5

9.0

9.5

10.0

11.0

12.0

13.0

14.0

15.0

16.0

17.0

18.0

2.2570

2.2220

2.1871

2.1521

2.1172

2.0909

2.0646

2.0119

1.9592

1.9066

1.8338

1.7610

1.6984

1.6359

1.5646

-17-

DT-500DRC (D) Voltage-Temperature Characteristic

24

23

22
21
20
19

18
17

16

15

14

13

12

19.0

20.0

21.0

22.0

23.0

24.0

25.0

26.0

27.0

28.0

29.0

30.0

32.0

34.0

36.0

38.0

40.0

45.0

50.0

55.0

60.0

65.0

70.0

75.0

80.0

1.4932

1.4219

1.3505

1.3006

1.2507

1.2114

1.1720

1.1486

1.1308

1.1190

1.1116

1.1058

1.0970

1.0902

1.0850

1.0798

1.0746

1.0633

1.0520

1.0407

1.0287

1.0166

1.0046

0.99172

0.97890

-18-

11

10

85.0

90.0

95.0

100.0

105.0

110.0

115.0

120.0

125.0

130.0

135.0

140.0

145.0

150.0

155.0

0.96609

0.95327

0.93987

0.92647

0.91307

0.89966

0.88626

0.87286

0.85946

0.84606

0.83228

0.81850

0.80472

0.79094

0.77716