Guildline 6636 User manual

OPERATORS MANUAL
FOR
MODEL 6636
RESISTANCE STANDARD
NOTICE
The contents and information contained in this manual are proprietary to
Guildline Instruments Limited. They are to be used only as a guide to the
operation and maintenance of the equipment with which this manual was
issued, and may not be duplicated or transmitted by any means, either in
whole or in part, without the written permission of Guildline Instruments
Limited.
OM6636-B-00
12 February 2015

HAZARDS WARNING!
TEMPERATURE STABILIZED RESISTANCE STANDARD
INSTRUMENTS
READ THESE SAFETY PRECAUTIONS BEFORE SETTING
UP OR USING THIS INSTRUMENT!
IMPROPER SETUP OR OPERATION OF THIS
INSTRUMENT CAN RESULT IN PERSONAL INJURY,
BURNS OR ELECTRICAL SHOCK!
Precautions, Safety and Preparation for Use
1. Thoroughly read the set up and operating procedures in
this manual before installing or using this instrument.
2. Select the proper line voltage on the back panel and use only the
proper fuse type and rating specified for this product.
3. The line power connection must have an earth ground conductor and
must be connected to the instrument only with the line cord supplied
or a proper line cord specified for the country of use. Operating
this instrument without a proper grounded line
connection can result in electrical shock hazard.
4. Observe all connector and terminal markings and ratings to avoid any
possible shock, or other hazard to the user of this instrument.
5. Under no circumstances should unqualified personnel operate or
service this instrument.
6. Do not connect the line power or operate this instrument with the
covers removed.
7. Do not touch exposed terminal connections or make or break terminal
connections with the instrument operating.
8. Operate this instrument only in a well ventilated and dry environment.
9. Do not touch or make any type of connection to the
resistance terminal connections while the measuring
instrument is in operation, to avoid SERIOUS
ELECTRICAL SHOCK HAZARD.

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i
TABLE OF CONTENTS
1. INTRODUCTION...................................................................................................1-1
1.1. SCOPE................................................................................................................................................... 1-1
1.2. GENERAL DESCRIPTION................................................................................................................ 1-1
1.2.1. Resistance Ranges...............................................................................................................................1-1
1.2.2. Non-Standard Model Configurations..................................................................................................1-1
1.3. FRONT PANEL INDICATORS AND CONTROLS......................................................................... 1-2
1.3.1. Power..................................................................................................................................................1-2
1.3.2. Heater..................................................................................................................................................1-2
1.3.3. Over Temperature...............................................................................................................................1-2
1.3.4. PRT.....................................................................................................................................................1-2
1.4. REAR PANEL CONNECTORS AND CONTROLS......................................................................... 1-3
1.4.1. Line Input Connector..........................................................................................................................1-3
1.4.2. Resistor Terminals..............................................................................................................................1-3
1.4.3. Guard Terminal...................................................................................................................................1-3
1.4.4. Chassis Ground Terminal....................................................................................................................1-3
2. SPECIFICATIONS................................................................................................2-1
2.1. GENERAL SPECIFICATIONS.......................................................................................................... 2-1
2.2. RESISTANCE SPECIFICATION ...................................................................................................... 2-2
3. OPERATING INSTRUCTIONS.............................................................................3-1
3.1. INSTALLATION.................................................................................................................................. 3-1
3.2. OPERATING NOTES.......................................................................................................................... 3-1
3.2.1. Connection to Standard Resistors .......................................................................................................3-1
3.2.2. Monitoring of the Internal Temperature..............................................................................................3-1
3.2.3. Power Entry Selection.........................................................................................................................3-2
4. MAINTENANCE....................................................................................................4-1
4.1. PREVENTIVE MAINTENANCE....................................................................................................... 4-1
4.1.1. Cleaning..............................................................................................................................................4-1
4.1.2. Temperature........................................................................................................................................4-1
4.1.3. Resistor Stability.................................................................................................................................4-1
4.2. CERTIFICATION OF RESISTANCES............................................................................................. 4-1

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4.3. CORRECTIVE MAINTENANCE...................................................................................................... 4-1
4.3.1. Preliminary Checks.............................................................................................................................4-1
4.3.2. Temperature Control...........................................................................................................................4-2
4.3.3. Over Temperature...............................................................................................................................4-4
5. PRINCIPLES OF OPERATION ............................................................................5-1
5.1. INTRODUCTION ................................................................................................................................ 5-1
5.2. TEMPERATURE SENSITIVE OSCILLATOR................................................................................ 5-2
5.3. AMPLIFIER AND DETECTOR......................................................................................................... 5-2
5.4. HEATER DRIVER............................................................................................................................... 5-3
5.5. OVERTEMPERATURE CIRCUIT.................................................................................................... 5-3
5.6. POWER SUPPLY................................................................................................................................. 5-4

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TABLE OF FIGURES
FIGURE 1-1: FRONT VIEW....................................................................................................................................1-2
FIGURE 1-2: REAR VIEW ......................................................................................................................................1-3
FIGURE 5-1: HEATER CONTROL UNIT ..............................................................................................................5-1
FIGURE 5-2: TEMPERATURE SENSITIVE OSCILLATOR.................................................................................5-2
FIGURE 5-3: AMPLIFIER AND DETECTOR........................................................................................................5-2
FIGURE 5-4: HEATER DRIVER.............................................................................................................................5-3
FIGURE 5-5: POWER SUPPLY...............................................................................................................................5-4

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LIST OF TABLES
TABLE 2-1: GENERAL SPECIFICATIONS...........................................................................................................2-1
TABLE 2-2: RESISTANCE SPECIFICATION........................................................................................................2-2
TABLE 4-1: CONTROL CIRCUIT BOARD TESTING..........................................................................................4-2
TABLE 4-2: TRANSISTOR VOLTAGES................................................................................................................4-4

Section 1
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1-1
1. INTRODUCTION
1.1. SCOPE
This manual contains technical specifications, a detailed description, maintenance information,
and diagrams for the Guildline Instruments model 6636 Resistance Standard.
1.2. GENERAL DESCRIPTION
The model 6636 Resistance Standard is a rack mountable or bench top instrument which
provides a set of precision resistance standards enclosed in a multi-walled constant temperature
chamber. The internal temperature is maintained by a solid state control system at 30 C
0.01 C. The design assures minimum thermal gradients within the inner chamber containing
the standard resistors. The resistors are immune to normal shock and vibration in commercial
carrier shipment.
To protect the standard resistors from overheating due to a malfunction of the temperature
control, there is an overriding over-temperature control that will disable the heating system if the
temperature exceeds 34 °C 3 C.
The model 6636 is intended to be used as Primary Resistance Standards, or Working Resistance
Reference Standards. The 6634A is particularly useful for an Automated High Resistance
Measurement System.
1.2.1. Resistance Ranges
Six resistor elements within the standard model 6636 configuration cover the range of
10 MΩto 1 TΩin decade steps. Each resistor element is isolated and has a 2 terminal
connection at the back panel.
1.2.2. Non-Standard Model Configurations
The 6636 can be supplied with resistance value in the range of 100 k to100 T . Only
six resistance elements may be installed in a single unit.

Section 1
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1-2
Figure 1-1: Front View
1.3. FRONT PANEL INDICATORS AND CONTROLS
The front panel indicators and controls are illustrated in Figure 1-1. They are provided to
indicate power status, heater operation and temperature status.
1.3.1. Power
The POWER indicator is lit when the AC power is applied to the unit and the power
ON/OFF switch on the rear panel is “ON”.
1.3.2. Heater
The HEATER indicator is lit when power is being applied to the heater.
1.3.3. Over Temperature
The OVER TEMP indicator is lit when the internal temperature has exceeded 34 °C
3 C. This may occur when the unit is operated in an ambient temperature in excess of
the operating temperature, or in the event of control failure.
1.3.4. PRT
The platinum resistance thermometer, imbedded within the temperature controlled
chamber, is configured as a four terminal resistor. The four terminals terminate in four
low thermal binding posts labelled “PRT”. The set of terminals consists of two black
binding posts for the 'P1' and ‘C1’ terminals, and two red binding posts for the ‘P2’ and 'C2'
terminals of the PRT. The ‘C’ terminals are to be connected to the current source and the
‘P’ terminals are to be connected to the potential measuring circuit of the resistance
measuring device. The temperature sensitivity of the PRT is 0.392 / C. The resistance
at 30 C is provided in the Report of Calibration. For accurate temperature measurement,
the resistance must be measured in four wire mode with an excitation current of 1 mA or
less.