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Tegam PRT73 Instruction And Service Manual

Precision ratio transformer
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MODEL PRT73
Precision Ratio Transformer
Instruction and Service Manual
PN# 70581
Publication Date: April 2015
REV. F
10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 •
www.tegam.com

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  • Page 1 MODEL PRT73 Precision Ratio Transformer Instruction and Service Manual PN# 70581 Publication Date: April 2015 REV. F 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 2 Electro-Scientific Industries (ESI), Gertsch, Keithley Instruments, Lucas Weinschel, and Pragmatic Instruments. A complete list can be viewed on our Product Service Directory at www.tegam.com For more information about TEGAM and our products, please visit our website at www.tegam.com: or contact one of our customer service representatives at sales@tegam.com or 800-666-1010.

  • Page 3: Table Of Contents

    Applying Three-terminal Corrections to AC Ratio Bridge Measurements ............3-15 Explanation of Mathematical Linearization and Comparison to Mechanical Linearization ..........3-17 Using the Model PRT73 as a Precision Attenuator 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 4 General Theory of Transformer Operation ............. 5-8 Transformer Ratio Switching Method ............5-8 Analog Status Signals and Transformer Relay Control ........ 5-13 Over-voltage Circuit Operation ..............5-14 VI. Installation 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 5 Over-voltage Circuit Calibration ............... 8-21 Troubleshooting Routine Checks ....................9-2 Problem Isolation ....................9-3 Voltage Entry, Voltage Select, and Power Supply Check ......... 9-6 Analog Cka Check Procedure ................9-8 Warranty 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 6: Safety Information

    Safety Information SAFETY INFORMATION 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 7: Safety Notices Appearing In This Manual

    Demagnetization” procedure in Section 8. Installation – Section 6… CAUTION: Components used in the Model PRT73 can be damaged by an electro-static discharge (ESD) when the covers are removed. To prevent ESD damage, the installation of the 2.5 V/Hz Option must be performed on a static-free worksurface.
  • Page 8 WARNING: Troubleshooting and repair of the Model PRT73 should be done only by qualified service representatives or by qualified service technicians. CAUTION: Components used in the Model PRT73 can be damaged by an electrostatic discharge (ESD) when the covers are removed. To prevent ESD damage, all work must be performed on a static-free work-surface.

  • Page 9: Safety Notices Appearing On The Model Prt73

    Any Terminal to Ground User applied voltage should not exceed 350 VRMS between the 1.1, 0.0., -.01 or GUARD inputs and Chassis Ground. Figure S-1, Front Panel Safety Label 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 10 220V 198-242V FUSE FUSE TT 500mA TT 250mA RANGE RANGE 240V 216-264V 120V 108-132V FUSE FUSE TT 250mA TT 500mA Figure S-2 Rear Panel Notices and Labels 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 11 Safety Information Top View Bottom View Figure S-3. Safety Label with Top and Bottom Covers Removed 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 12: General Description

    General Description General Description 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 13 AC signals in the audio frequency range. The Model PRT73 is a seven-decade AC divider with 0.9 ppm (±0.0000009) terminal linearity and 0.1 ppm of resolution for ratio settings from -0.0010000 to 1.0009999.
  • Page 14 “OVERLOAD” message will appear on the front panel display. The Model PRT73 can be used on the bench or in a rack with the addition of a rack mount option. All necessary hardware is supplied for rack mounting the Model PRT73 in a standard 19 inch width rack mount console.

  • Page 15: Specifications

    Specifications Specifications 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 16: Maximum Ratings

    -0.001 to 0.01 is traceable to N.I.S.T. uncertainty of 0.5 ppm of input. ±(0.9 100 x Setting + 0.01ppm) for 50 Hz to 200 Hz settings -0.001 to 0.01 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 17 Verification with NIST traceability 20 µrad at 100 Hz, increasing to 100 Hz to 1 kHz limited to 5.0 ppm of input. 200 µ rad at 1 kHz 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 18 -0.0010000 to + 1.0009999 2.5 V/Hz Range -0.00010000 to + 1.00009999 Input Inductance 0.35 V/Hz Range 100 H to 400 H 2.5 V/Hz Range 700 H to 2.1 kH 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 19 Measurements valid with input 0.35 V/Hz Range 400 mΩ to 7 Ω shorted. 2.5 V/Hz Range 500 mΩ to 12 Ω The series inductance will vary with ratio setting. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 20: Gpib Communications

    4-10) for further information. Interface Function Codes See Section 4 GPIB Interface SH1,AH1,T6,L4,SR1,RL1,PP0,DC1, DT1,C0,E2 Function Codes (p. 4-9) for further information. Connector Type Female 24-pin, D shell 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 21: Environmental Specifications

    5.25 in. (13.3 cm) Width: 17 in. (43.2 cm) Depth: 20 in. (50.8 cm) Weight Net Without Options 30 lbs (13.8 kg) Shipping Weight 40 lbs (18 kg) 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 22: Operation

    Operation OPERATION 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 23 Operation Operation Information in this section describes how to operate the Model PRT73 using the front and rear panel controls. For information on programming commands and communication, refer to Section 4 – Remote Communication. Table 3-1. Operation Section Contents Using the Front and Rear Panel Controls……………………………………………………………………..3-3 Input………………………………………………………………………………………………………………………………3-4...

  • Page 24: Using The Front And Rear Panel Controls

    8 ½ characters are displayed when the 2.5 V/Hz option is installed and enabled. MENU – Rear panel push button that switches the Model PRT73 into the menu mode for setting the GPIB address and message terminators. The Model PRT73 must be in local mode (GPIB REN line (0)) to enable menu mode.

  • Page 25: Input

    Operation Input The binding posts in the INPUT section of the Model PRT73 are not all used as voltage inputs. Only the 1.0 and 0.0 binding posts are normally used as inputs from AC signal sources. The 1.1 and -0.1 binding posts are used as outputs to drive phase correcting devices when making ratio comparison measurements.

  • Page 26: Over-Voltage Protection

    2.5 V/Hz range in the event of an overload at frequencies below 1 kHz. For example, if the over-voltage circuit is activated when the Model PRT73 is in the 0.35 V/Hz range and the 2.5 V/Hz option is installed, the software will open the input relay and then check to see if an overload condition would exist in the 2.5 V/Hz range.

  • Page 27: Important Notes About The Over-Voltage Circuit And Your Generator

    To recover from the overload, the amplitude of the generator must be reduced until the over-load is relieved. If the signal source is a current source, the amplitude may need to be reduced to zero. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 28: 1.1 And -0.1 Signal Requirements And Restrictions

    For this reason, it is recommended that the 0.0 and GUARD terminals be connected to chassis ground somewhere in the test setup. This can be done at the Model PRT73 by connecting the 0.0, GUARD, and Chassis Ground together.

  • Page 29: Output

    Operation Output The output of the Model PRT73 is an accurate portion of the applied input signal as displayed by the multiplier set on the front panel. The nominal voltage output is calculated by (V x ratio setting). Ratio settings between -0.001 and +1.0009999 are possible.

  • Page 30: Operating Modes

    The IEEE-488 setup mode is entered by pressing the rear panel IEEE-488 Setup Mode push button when the Model PRT73 is in the local mode. Once in the IEEE-488 mode, the GPIB address and input/output message terminators can be selected. There are three main screens that are changed by using the left most ratio push buttons.
  • Page 31 Operation Enter the setup mode by pressing the IEEE-488 SETUP push button on the rear panel when the Model PRT73 is in the local mode. The last variable displayed in the menu screen is the setting saved. To exit the menu mode, press the 2.5V/Hz, 0.35 V/Hz, 1.0,...

  • Page 32: Applications Of The Model Prt73

    0.0 INPUT (the 0.0 OUTPUT terminal is not used). The most common application where the Model PRT73 is used as a three-terminal device is as part of an AC ratio bridge. In an AC ratio bridge the Model PRT73 becomes the standard for direct comparison to another device.

  • Page 33: Using The Model Prt73 In An Ac Ratio Bridge

    Using the Model PRT73 in an AC Ratio Bridge (A Three-terminal Application) A typical setup using the Model PRT73 in an AC ratio bridge is shown in Figure 3-5. An AC ratio bridge is commonly used to calibrate the following devices: Other Ratio Transformers.

  • Page 34: Components Of A Ratio Bridge

    AC ratio bridge test setup. AC Generator. An AC generator for use with the Model PRT73 needs to output a low distortion sine-wave with no DC component at 2 – 200 Vrms 10 TEGAM WAY •...
  • Page 35 When using the Model PRT73 to achieve a null, a resolution of 1 x 10 or 0.1 ppm of input is obtained. Use of the 2.5 V/Hz Option with the Model PRT73 will extend the resolution to 1 x 10 or 0.01 ppm.

  • Page 36: Applying Three-Terminal Corrections To Ac Ratio Bridge Measurements

    In AC ratio bridge applications where measurements require this type of accuracy, you will probably be using the Model PRT73 as a standard to calibrate you bridge setup. Whether you use the C or C’ corrections to calibrate your test setup depends on...
  • Page 37 In the simplified drawing of Figure 3-7, we see two ratio transformers. The ratio transformer on the right is the Model PRT73 that will be used as the standard to calibrate the AC ratio bridge setup. The ratio transformer on the left is part of the AC ratio bridge.

  • Page 38: Explanation Of Mathematical Linearization And Comparison To Mechanical Linearization

    System corrections are obtained and the AC bridge is said to be calibrated by calculating the difference between the measured deviation and the Model PRT73’s corrections at each setting of the first three decades (subtracting the measured deviation values from the standard’s corrections).

  • Page 39: Operation (Continued)

    = Deviation of UUT 1.0 INPUT to AC Bridge transformer 1.0 TAP OUTPUT = Ratio at tap setting = Transfer Ratio Correction Figure 3-8. Measurement Errors Eliminated by 1 Linearization Formula 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 3-18...
  • Page 40 The result of the measurements using the mechanical lead balance are equal to the End Adjusted Linearity Corrections (C’) obtained with the mathematical technique. See Figure 3-10. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 3-19...

  • Page 41: Using The Model Prt73 As A Precision Attenuator

    Using the Model PRT73 as a Precision Attenuator (A Four-terminal Application) Another significant use of the Model PRT73 is a four-terminal attenuator to produce high accuracy AC voltage at low levels. See Figure 3-11. In this application, a known stable voltage is applied to the input terminals, between INPUT 1.0 and INPUT 0.0.

  • Page 42: Calibration Of An Ac Voltmeter

    Calibration of an AC voltmeter at millivoltmeter levels requires applying a known voltage at the input of the Model PRT73. This may be accomplished by direct connection to an accurate AC calibrator using short, heavy leads, or more preferably by using the remote sensing (if available) from the generator to establish the generator output at the plane of the input terminals of the divider.

  • Page 43: Calibration Of Mv Ranges On Ac Calibrators

    A possible source of error in this hookup is the loading of the voltmeter on the output of the Model PRT73. Assuming the Model PRT 73 is driven by an AC source with an output impedance below 10 Ohms, the worst case equivalent impedance between the OUTPUT 1.0 and 0.0 terminals will approach 7 Ohms in series with 30 microhenries.
  • Page 44 4. Reduce output of AC calibrator to 100 mV and adjust for same reading on AC millivoltmeter or record deviation Figure 3-13. Calibrating Lower Ranges of an AC Millivoltmeter 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 3-23...

  • Page 45: Remote Communication

    Remote Communication REMOTE COMMUNICATION 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 46 GPIB Address and Message Terminator Settings………………………………………………..4-10 Pin Assignments………………………………………………………………………………………………..…..4-11 Bringing the Model PRT73 Up in GPIB…….…………………………………………………………….4-12 Programming Commands…………………………………………………………………………………………..4-13 Command Class Definition.……………………………………………………………………………………4-13 Input Command Syntax………………………………………………………………………………………..4-13 Output Command Syntax……………………………………………………………………………….…….4-13 Commands………………………….…………………………………………………………………………….……4-14 Error Messages…………………………………………………………………………………………….…..…..4-17 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 47: Ieee-488

    The GPIB interface is designed to communicate through a parallel port, as defined by the IEEE- 488 Interface Specification. This allows the exchange of commands and responses between a host controller and the Model PRT73. For information on the commands used to control the Model PRT73 refer to Programming Commands on page 4-12.
  • Page 48 Those devices that have the capability to talk and listen are designated as slaves. The Model PRT73 is only capable of being a basic talker or a basic listener (Slave). The way the controller designates what function each slave performs is by addressing the slave and issuing an interface message.

  • Page 49: Signal Lines

    One eight-bit word can be transmitted bi-directionally in bit-parallel, byte-serial fashion. The data lines are considered active when their signal level is LOW. Figure 4-1. GPIB Signal Lines and Device Functions 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 50 DAV line HIGH until the handshake cycle is repeated. NOTE: Data Lines Are Active When Low Figure 4-2. A Typical Handshake Cycle 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 51 If the Model PRT73 is in the middle of a data transfer, it will clear the bus and then clear the buffered portions of the message.

  • Page 52: Gpib Interface Function Codes

    (some with as many as 28 subsets identified by a numeric value after the code) supported by, and included in, the interface standard. Table 4-3 identifies the functions supported by the Model PRT73 by listing the 12 function codes and Model PRT73 capabilities defined by the subset number.

  • Page 53: Serial Poll Status Byte

    Table 4-4. Serial Poll Status Byte Definition Busy Bit (B) – The Busy bit is set whenever the Model PRT73 is actively processing data as a response to a control button being pressed of from a remote command. The Ratio, Range, and Reset commands cannot be executed when the Busy bit is true.

  • Page 54: Gpib Address And Message Terminators

    The selections are accessible by entering the IEEE setup mode by pressing the IEEE-488 SETUP button on the back panel of the Model PRT73. Use the left most ratio push buttons to select the message terminator and address screens and use the right most push buttons to select the desired parameters.

  • Page 55: Gpib Address Selection

    EOI on CR CR + EOI on lf GPIB Address selection The Model PRT73’s device address is set decimal format from 0 to 30. Pin Assignments The Model PRT73 GPIB interface uses a female, 24-contact trapezoidal, D-shell connector. See Figure 4-3 for contact assignments.

  • Page 56: Bringing The Model Prt73 Up In Gpib

    Activate the host controller and turn on the REN line. At this point, the GPIB will still be in the inactive state. When a listen address is seen by the Model PRT73, it will activate the GPIB interface and the Model PRT73 will switch to the remote mode.

  • Page 57: Programming Commands

    Remote Communication Programming Commands The Model PRT73 is designed to be used in an automated system environment and controlled by a PC other form of host controller through an IEEE-488 interface. Typically the Model PRT73 will be controlled by the host controller running an application specific program written by the user.

  • Page 58: Commands

    Overloadreset (OVR) Class: Read Only Description: Resets the Over-voltage bit in the serial poll status byte. See Serial Poll Status Byte p. 4-9. Input> Overloadreset Output> Overloadreset 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 4-14...
  • Page 59 Class: Set/Read Parameters: Alpha-numeric string (0-9, E, D,.) Description: Reads or sets the RATIO setting of the Model PRT73. Returned values will always be 10 characters long with the decimal point in the second character. Parameters are accepted with + or – signs, floating decimal point, variable number of digits, and an exponent (E or D).
  • Page 60 Class: Action Description: Returns the remote/local control status of the Model PRT73. A 0 indicates the Model PRT73 is in the remote mode of operation. A 1 indicates the Model PRT73 is in local mode. See Operating Modes p. 3-10.

  • Page 61: Error Messages

    !VTS Value Too Small Action: Enter command again using a parameter within the range. !WNA Wrong Number of Arguments Action: Check your parameters and input again. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 4-17...

  • Page 62: Theory Of Operation

    Theory of Operation THEORY OF OPERATION 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 63 Theory of Operation This section contains general operation descriptions of the circuit assemblies contained in the Model PRT73. Reading this section will aid a technician if troubleshooting the Model PRT73 becomes necessary. Table 5-1. Theory of Operation Contents Block Diagram ..................... 5-3 8088 CPU W/IEEE Circuit Card .................

  • Page 64: Block Diagram

    In critical locations, pairs of contacts are connected in parallel for extended-life operation. The CPU/IEEE circuit card controls all of the functions of the Model PRT73 using an 8088 microprocessor and custom software programmed into ROM. Communication from the microprocessor to the Front Panel circuit assembly is handled by a static bus;...
  • Page 65 Theory of Operation Figure 5-1. Model PRT73 Block Diagram 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 66: 8088 Cpu W/Ieee Circuit Card

    Theory of Operation 8088 CPU W/IEEE Circuit Card Control of all the Model PRT73 operations and the GPIB I/O are provided by the 8088 CPU W/IEEE-488 circuit card. The card basically contains an 8088 microprocessor, an 8k x 8 SRAM, ROM, associated latches and buffers and PALs for address and data I/O, a standard IEEE-488 controller, and IEEE-488 transceivers.

  • Page 67: Clock

    The RESET signal sent to the Front Panel circuit card is applied to a PAL (U15) and then to • the front panel controller (U12). The low signal on (U12) sets the display to 0.00000. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 68: I/O Monitoring

    • Analog circuit card to a 0.00000 ratio. This is a safety mechanism designed to protect the Model PRT73 and the equipment connected to it from potentially high surge voltages that may be present when power is restored. The RESET signal to the GPIB controller (U13) resets the GPIB to a non-remote state.

  • Page 69: Front Panel

    As long as the button is pressed down, the decade will increment or decrement provided it is a valid ratio that the Model PRT73 can achieve. The front panel controller (U12) monitors the remainder of the controls, and displays. All the LEDs and the seven-segment displays are multiplexed using U10 and U11.

  • Page 70: Analog Circuit Card

    Analog Circuit Card General Theory of Transformer Operation The output voltage at the TAP of the Model PRT73 is produced by the operation of three transformers. The first transformer divides the input voltage into 10% steps with a tap at each step. This transformer is constructed with a twisted bundle of 12 wires wrapped 100 times through a high permeability core.
  • Page 71 1.0009999 to 0.9890000 without changing the taps on the first and second decades. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 72 Theory of Operation Table 5-2. Ratio Settings that use Over – and Under – windings 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 5-11...
  • Page 73 Diagrams and Parts List section for circuit reference. The Transition Relays are energized only when a digit setting is changed in a particular decade. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 5-12...
  • Page 74 These latches and relays are energized only during the period of time the ratio is changed. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 75: Analog Status Signals And Transformer Relay Control

    +12 V supply. The status of the option is checked when the Model PRT73 is powered up. Conversely, the over- voltage and power interrupt circuitry are continuously monitored. Any time an over-voltage occurs most of the signal relays are opened and the microprocessor is alerted to this condition.

  • Page 76: Over-Voltage Circuit Operation

    The standard Model PRT73 has a 0.35 V/Hz relationship, but with the low frequency option this would increase to 2.5 V/Hz. To accommodate these different relationships a relay (K57) is used to change the integrator feedback capacitor value from 0.022 µF (C3) in the 0.35 V/Hz range to...

  • Page 77: Installation

    Installation Installation 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 78: Model Prt73 Rack Mount Installation Instructions

    Model PRT73 Rack Mount Installation Instructions These instructions explain how to install the Model PRT73 Rack Mount kit (P/N 70192) and (P/N 70192/SP3293). The kit includes all necessary hardware. Figure 6-1 shows an exploded view of the Rack Mount Option.
  • Page 79 Figure 6-2. Figure 6-2 Removing End Caps 2. Insert the PRT73 Rack Mount Bar as shown into each side of the Model PRT73 and secure the new back end cap with two 8-32 x .75 Allen head screws at the rear of the Model PRT73. Secure the new Front End Caps and the PRT Rack Mount Bar to the Model PRT73 using two 8-32 x .75...
  • Page 80 5. Install both Rack Mounts to your Rack Unit using eight 10-32 x 0.5 PHP screws. Then slide the Model PRT73 into the Rack Mounts and secure the Model PRT73 to the Rack Unit with four 10-32 x 0.75 PHP screws. Refer to Figure 6-5.

  • Page 81: 2.5 V/Hz Option Installation Instructions

    Installation 2.5 V/Hz Option Installation Instructions These instructions explain how to install the Model PRT73 2.5V/Hz option kit (P/N 70161). When properly installed the 2.5 V/Hz option will perform to published specifications listed in the Model PRT73 Instructions Manual (P/N 705181). To receive correction values for the 2.5 V/Hz operating range, send the Model PRT73 to TEGAM Inc.
  • Page 82 Installation Figure 6-6. Removing Top Cover of Model PRT73. Figure 6-7. Model PRT73 with Top Cover Removed. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 83 CPU-Analog Cbl (P/N 68996) from J2 on CPU Cka (P/N 68700) • 6. Lift the Guard Box straight up from the Model PRT73 chassis and place it on static- free work surface. Figure 6-8. Top View with Guard Box Top Removed 10 TEGAM WAY •...
  • Page 84 9. Install the 2.5 V/Hz Cka (P/N 69511) using the six screws supplied in the kit. Refer to figure 6-9. Figure 6-9. Guard Box Removed from Chassis 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 85 Guard Box top cover (four screws). Connect the CPU-Front Panel Cbl (P/N 68995) to J1 on the CPU Cka (P/N 68700). Refer to Figure 6-7. 16. Connect the top cover and secure with four screws on the bottom of the Model PRT73. See Figure 6-6.
  • Page 86 2.5 V/Hz operating range by using the Performance Check Procedure in the Model PRT73 Manual. If you don’t have a calibrated AC ratio bridge, you can send the Model PRT73 to TEGAM for certification, to the National Institute of Standards and Technology, or to another standards laboratory that offers this service.

  • Page 87: Maintenance

    Maintenance MAINTENANCE 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 88 Removal of instrument covers may constitute an electrical hazard and should be accomplished by qualified service personnel only. Remove AC power to the Model PRT73 before attempting to clean or perform a visual inspection. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 •...

  • Page 89: Cleaning

    Interior Cleaning the interior is not recommended unless the Model PRT73 is operated in a dirty environment. If you need to clean the interior of the Model PRT73. Use an anti-static strap attached to the Model PRT73 and yourself to protect the Model •...

  • Page 90: Visual Inspection

    Verify the vents located around the Model PRT73 remain clear at all times. Overheating will result if the vents become blocked. A visual inspection of the interior of the Model PRT73 is not recommended unless the interior needs cleaning or calibration is required.

  • Page 91: Performance Check And Calibration

    Performance Check and Calibration PERFORMANCE CHECK AND CALIBRATION 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 92 Procedures in this section are to be performed by qualified personnel only. The performance check procedure is a tool used to verify that the Model PRT73 is performing within its calibration specifications by comparison to a calibrated AC ratio bridge. It is to be performed: At scheduled times as part of your maintenance program •...

  • Page 93: Performance Check Procedure

    Standard Research System SR 530 AC Generator Fluke 5700A or Datron/Wavetek 4200 Phase Compensation PC874 Isolation Transformers 1:1 with primary and secondary shields 3 ½-digit Digital Voltmeter Oscilloscope with X-Y mode 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 94: Over-Voltage Circuit Test And Input Transformer Demagnetization

    DC component. 1. Setup the test equipment as shown in Figure 8-1. 2. Set the Model PRT73 to the 0.35 V/Hz operating range and the generator to 60 Hz and 0 V. Figure 8-1. Test Equipment Connections for Transformer Demagnetization 3.
  • Page 95 If the circuit is working properly, an “OVERLOAD” message will appear on the Model • PRT73’s display between 21 V and 23.1 V. If the 2.5 V/Hz option is installed, the range will change to 2.5 V/Hz (if the voltage does not also exceed the 2.5 V/Hz operating range).

  • Page 96: Linearity

    Performance Check and Calibration Linearity Test The linearity test is used to verify that the Model PRT73 is operating within its rated specifications or to calibrate the Model PRT73 or other ratio transformers. When you calibrate a Model PRT73 or other ratio transformer, you actually create a new set of correction values; you do not make any adjustments.
  • Page 97 The standard ratio transformer should be a certified Model PRT73 or DT72 with a certificate or corrections traceable to NIST.

  • Page 98: Verifying Or Generating Three-Terminal Corrections (C & C')

    Guard Voltage Driver – The guard voltage is generated by either a DT72 or Model PRT73. During calibration, the ratio of the guard voltage driver is set to the same ratio as the system AC ratio divider.
  • Page 99 Figure 8-2. Alternate Test Equipment Setup for Testing Linearity. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 100 Performance Check and Calibration Figure 8-3. Test Equipment Setup for Testing Linearity 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-10...
  • Page 101 246944 09/05/90 Maximum Positive 0.21 0.18 Measurement System readings 12/10/90 Maximum Negative -0.16 -0.17 Figure 8-4. Sample of Correction Values to be Generated Page 1 of 2 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-11...
  • Page 102 1 kHz 13816 246944 09/05/90 Maximum Positive 0.21 0.18 Measurement System readings 12/10/90 Maximum Negative -0.16 -0.17 Figure 8-5. Measurements Recorded to Calculate Scale Factor Value 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-12...
  • Page 103 NIST Deviation of step 2: Standard values to obtain System Correction in Voltage ppm values = Deviationinppm Scale Factor Figure 8-6. Measurements Recorded to Calculate System Correction Values 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-13...
  • Page 104 . Record this value including sign (+/-) for the Test Unit Scale Factor. Step 6B Step 6D Step 6E Scale Factor Figure 8-7. Measurements Recorded to Calculate Scale Factor Value for UUT 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-14...
  • Page 105 R1 = R2 will cause gain and offset error in R3 = R4 your corrections Figure 8-8. System Offset and Gain Errors Due to Unbalanced Lead Resistance. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-15...
  • Page 106 Step 8. Add the UUT Deviation in ppm values to the System Correction in ppm values to obtain Corrected UUT in ppm values. Figure 8-9. Calculating Corrected UUT Values 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-16...
  • Page 107 Correction (C) values. Use the formula in Figure 8-11. Step 9A Step 9B, & 9D & 9E Step 9C, & 9F Figure 8-10. Measurements at UUT 1.0 and 0.0 INPUT Terminals with Corrections 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-17...
  • Page 108 = Deviation of UUT 1.0 INPUT to AC Bridge transformer 1.0 TAP OUTPUT = Ratio at tap setting = Transfer Ratio Correction Figure 8-11. Linearization formula for Transfer Ratio Corrections (C) 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-18...
  • Page 109 The corrections (C) are of the same type generated by NIST standard ratio transformer measurements. The corrections (C’) are similar in type to those TEGAM has historically supplied on calibration certificates for the DT72. 11. Set the AC generator to output 10V at 100 Hz. Repeat this entire procedure to obtain 100 Hz correction values.

  • Page 110: Verifying Or Generating Four-Terminal Corrections

    This procedure will generate two sets of four-terminal correction values for use when the Model PRT73 is configured as an attenuator or four-terminal device. These corrections take into account the small error between the 0.0 INPUT terminal and the 0.0 OUTPUT terminal.
  • Page 111 Performance Check and Calibration Figure 8-13. Calculating DEVIATION OF OUTPUT LO Values 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-21...
  • Page 112 Ratio Correction ppm/Input (D) values by the ratio setting: Formula: D/r = D’ r = Ratio tap setting D = Four-terminal Ratio Correction ppm/input D = Four-terminal Ratio Correction ppm/output 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-22...
  • Page 113 DETECTOR SCALE FACTORS REFERENCE DATA Standard Voltage at 0.0 _____ ________ Standard S/N ___________ Voltage at FS Change ______ ________ Calibration Date ___________ Scale Factor ______ ________ NOTES: 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-23...
  • Page 114 REFERENCE DATA Voltage at 0.0 _____ Standard S/N __________ Voltage at FS Change ______ Calibraton Date __________ Scale Factor ______ NOTES: Figure 8-15. Four-terminal Correction Record 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-24...

  • Page 115: Over-Voltage Circuit Calibration

    1. Switch the instrument POWER OFF and unplug it from its power source. 2. Set the Model PRT73 on a static-free work surface. Remove the top cover by removing four screws from bottom of instrument. See Figure 8-16. Bottom...
  • Page 116 R_on the +12 V Power Supply for a reading of +12 V (±50 mV). 7. Proceed to the “Over-voltage Circuit Test and Input Transformer Demagnetization” (p. 8-4) and complete the procedure to verify the operation of the over-voltage circuit. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 8-26...

  • Page 117: Troubleshooting

    Troubleshooting Troubleshooting 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...

  • Page 118: Routine Checks

    Model PRT73 is functioning properly. 3. Visual Check. Visually check the portion of the Model PRT73 where the trouble is suspected. Many problems can be located by visual indications such as bad connections, broken wires, damaged circuit cards, damaged components, or components bent over and touching.

  • Page 119: Problem Isolation

    ESD B. There is no output voltage or the output voltage problem areas. If none exist and the Model PRT73 is operated in a is grossly inaccurate for some ratio settings. relatively static-free environment, return the Model PRT73 for repair.
  • Page 120 Clock circuit on 8088 CPU Cka – Monitor U1, pin 1 on the 8088 CPU for a 1200 Hz signal. Replace the 8088 CPU Cka or send the Model PRT73 in for repair if no signal is present. If the signal is present and the problem does not go away when the Front Panel Cka is swapped, return the Model PRT73 for repair.
  • Page 121 8 or 17. If a strobe signal is not present either U10 or U12 is not functioning properly. In either case, replace the Front Panel Cka or send the Model PRT73 in for repair. One segment of one LED display does not light or LED Faulty LED or LED display –...

  • Page 122: Voltage Entry, Voltage Select, And Power Supply Check

    • If the line voltage is correct, continue. 2. Switch system power off and unplug the main AC power cord from the Model PRT73. Check the Model PRT73. Check the Model PRT73’s fuse for the proper voltage and load rating.
  • Page 123 Front Panel Cka from the 8088 CPU Cka. Then sequentially reconnect each connector J6, J17, J1 to their respective circuit assemblies until the problem reappears. The Cka that is causing the short should be sent back to TEGAM for repair.

  • Page 124: Analog Cka Check Procedure

    Figure 9-4. Accessing the Power Supplies Analog Cka Check Procedure 1. Set the Model PRT73 on a static-free work surface. Remove the top cover by removing four screws from bottom of the instrument. See Figure 9-1. 2. Remove the Guard Box cover by disconnecting J1 on the 8088 CPU Cka and the four screws at each corner of the cover.
  • Page 125 +12 V ± 50 mV on TP3 -5 V ± 50 mV on TP5 +5 V ± 200 mV on TP6 Figure 9-5. Power Connectors on Analog Cka 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com...
  • Page 126 Troubleshooting 6. Perform a rough linearity test of the Model PRT73 for each digit on all decades. A linearity test can be performed by comparing each setting of the Model PRT73 against another ratio transformer or by inputting a known value and measuring the output with a millivoltmeter.
  • Page 127 • Starting with a ratio of 0.000000, increment the 10 decade to 1. The output voltage of the Model PRT73 should increase by approximately 10 µV. Each change in the 10 decade should now show an equal increase in voltage.
  • Page 128 Analog Cka, then lift the Gurard Box straight up from the chassis and place it on a static- free work surface. Figure 9-7. Removing the Analog Guard Box 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 9-12...
  • Page 129 Analog Cka. DO NOT pull on the wires to remove the connectors or they may be damaged. Refer to detail A in Figure 9-8. Figure 9-8. Removing Transformer Connectors 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 9-13...

  • Page 130: Preparation For Calibration Or Repair Service

    Once you have verified that the cause for 1830A malfunction cannot be solved in the field and the need for repair and calibration service arises, contact TEGAM customer service to obtain an RMA, (Returned Material Authorization), number. You can contact TEGAM customer service via the TEGAM website, www.tegam.com...

  • Page 131: Repair Instructions

    When is the problem most frequent? Has anything changed with the application since the last time the instrument was used?, etc. 10 TEGAM WAY • GENEVA, OHIO 44041 440-466-6100 • FAX 440-466-6110 • www.tegam.com 10-2...

  • Page 132: Warranty Information

    TEGAM service center with shipping charges prepaid. TEGAM Inc. shall pay for the return of the product to the customer if the shipment is to a location within the country in which the TEGAM service center is located. The customer shall be responsible for paying all shipping, duties, taxes, and additional costs if the product is transported to any other locations.

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