Shaun Merrigan's Information Pages


Category: Electronics


Tektronix SG5010 Audio Signal Generator Repair

Posted by Shaun Merrigan in Audio, Electronics, Test Equipment. Comments Off on Tektronix SG5010 Audio Signal Generator Repair

14th December

Background

The Tektronix SG5010 is an audio signal generator plug-in for the TM5000 modular test equipment system. It can generate five waveforms: sine wave, square wave, SMPTE/DIN intermodulation test signal, CCIF intermodulation test signal, and sine wave burst. All these signals may be swept in frequency and amplitude. It can generate very low distortion (THD+N < 0.0008%; my own measurements) sine waves from 20Hz-20kHz. It is CPU controlled with selections made via GPIB or front panel keyboard. These characteristics made it very desirable as part of an audio amplifier test lab. These units command a high price: Several working units have recently (Dec 2023) been sold for $USD 1500.

I recently acquired a non-working SG5010 for a good price. This post documents my efforts (ultimately successful) in getting it working.

Tektronix SG5010 Overview

Tektronix SG5010 Front Panel

First … Read More »


Tektronix CG5001 Calibration Generator Repair

Posted by Shaun Merrigan in Electronics, Test Equipment. Comments Off on Tektronix CG5001 Calibration Generator Repair

12th December

The document describes the repair process of a Tektronix CG5001 Calibration Generator. It discusses the errors encountered during the power-up self-test and the components that were found to be faulty. The document also mentions the use of extender cables during the diagnostic and repair process.


Analysis of Sprague 672D Capacitor Failures in vintage HP Test Equipment

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Analysis of Sprague 672D Capacitor Failures in vintage HP Test Equipment

28th November

Shaun Merrigan investigated Sprague 672D Electrolytic capacitor failures in the HP 70000 MMS test equipment. He found that due to thousands of hours of running time and high internal temperatures, many capacitors have failed. The capacitors made before 1990 are highly prone to failure, while those made between 1990-1999 show signs of aging. He replaced the faulty capacitors with Chemi-Con KYA and KZN series capacitors and all modules are now functioning properly.


HP 70100A Power Meter Rubber Pad Replacement

Posted by Shaun Merrigan in Electronics, Restoration, Tech, Test Equipment. Comments Off on HP 70100A Power Meter Rubber Pad Replacement

24th November

The Hewlett Packard 70100A is the power meter module in the HP 70000 modular test system. This post will document a problem common to three 70100A units I have recently restored.

As part of the restoration process, I opened the modules to perform a visual inspection. What I found under the outer cover was this:

70100A PS CPU Board Solder Side Overview before repair

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

HP 70100A PS CPU Board Deteriorated Rubber Pads

The rubber spacer pads between the circuit boards and the outer metal cover had deteriorated to the point of liquifying and running down board via gravity. All the pads in the three units I examined were afflicted to some degree. Several years ago, I documented a similar phenomenon … Read More »


Tektronix 284 Pulse Generator Repair

Posted by Shaun Merrigan in Electronics, Restoration, Test Equipment. Comments Off on Tektronix 284 Pulse Generator Repair

21st November

This post will document my recent repair of a Tektronix 284 Pulse Generator. This device was introduced by Tektronix in 1967. It can produce:

A 50kHz, 200mv fast risetime pulse. Typically, tr < 70 ps

A 100 kHz, 1 MHz, or 10 MHz square wave at 10, 100, or 1000 mV

A 100 MHz or 1 GHz sine wave at 100 mV

The Tektronix 284 can be used to check the risetime of oscilloscopes, (both sampling and real time) amplifiers, transistors, transient responses, and for TDR work. The pulses are generated by a tunnel diode which is a semiconductor device capable of changing states very quickly. Tunnel diodes were invented in the late 1950’s in Japan and widely used in test equipment through the 1970’s. Tektronix used tunnel diodes in “pulsers” like the 284 and many oscilloscopes including the … Read More »


HP 70001A Power Supply Refresh

Posted by Shaun Merrigan in Electronics, Test Equipment, Troubleshooting. Comments Off on HP 70001A Power Supply Refresh

17th November

I have recently begun to restore several pieces of Hewlett Packard 70000 Series MMS (Modular Measurement System) equipment. The basic component of the system is a power and/or display frame which can house various test equipment modules. This post documents my restoration of the HP 70001A Power Supply.

The Hewlett Packard 70000 MMS is a high-performance, modular measurement system for RF, microwave, and Lightwave measurements. The MMS instruments include spectrum analyzers, signal generators, power meters, DMM, digital oscilloscope, counter, and more. The system is assembled by inserting the appropriate modules into a mainframe (which supplies power, cooling, and communication) along with a display.

Historically, the 70000 MMS system was introduced in 1986 and continued to be available through at least 2001 (based on HP/Agilent catalogs). The latest prices (1993) I could find for a couple of representative HP 70000 systems follows (all … Read More »


Vacuum Tube Tester: The Roetest

Posted by Shaun Merrigan in Electronics, Tech, Test Equipment, Vacuum Tubes. Comments Off on Vacuum Tube Tester: The Roetest

17th March

I recently completed the construction of a PC controlled vacuum tester: The Roetest. This is a computer-controlled tube tester which works as follows:

Using the PC software, load the tube data from the extensive database

Verify the tube data and pinout on the screen; the tester configures the pin connections automatically

Run the tests for shorts and filament continuity

Run the required tests

Test the tube at full voltage and current (not a pulse test)

Save the result

Add the tube and test data to inventory

Roetest V10 Front Panel and case

Roetest V10 Main board and plug in boards

Roetest V10 Front Panel

Construction Details:

4600 Solder Joints

600+ Components

20 separate circuit boards

Mechanical work for socket boxes + drilling and tapping heatsink

150+ hours

Using the PC software, load the data for the TUT (Tube under Test). Pinout and base connection information is taken from an extensive database of over 22,000 tube types.

Roetest … Read More »


Tektronix TM500 Module Holder

Posted by Shaun Merrigan in 3D Printing, Electronics, Restoration, Tech. Comments Off on Tektronix TM500 Module Holder

28th June

I have previously written about the substantial number of different modules available for the Tektronix TM500 and TM5000 module plug-in systems. Since the equipment is now anywhere from 20 – 40 years old it needs to be refreshed and/or repaired before going back into service. This often means working on the modules while they are not installed in the power frame:

TM500 Extender Overview: Connects between module and power frame.

TM500 Extender Overview: Connects between module and power frame.

Dan Meeks Extender Closeup. This extender allows monitoring of all supply voltages and currents. It also has LED indicators for each voltage rail.

Extender Plugged into Power Frame

Extender Plugged into module. This allows working on the module outside of the power frame.

From the image above, the extender board projects beyond the edges of the plug-in. This means that the plug in … Read More »


Tektronix TM500 Power Frame Tester

Posted by Shaun Merrigan in Electronics, Test Equipment. Comments Off on Tektronix TM500 Power Frame Tester

25th June

The Tektronix TM50n is an “n”bay (where n = 1 to 6, the number of bays) power frame which can host and power TM500 plug-ins. It was available in 1 through 6 bay versions and was the predecessor to the TM5000 power frame: See my post here about the TM5000 power frames. Tektronix themselves had dozens of plug-ins available which comprised power supplies, signal generators, oscilloscopes, multimeters, test oscillators, calibrators, attenuators, filters, logic analyzers, frequency counters, audio analyzers and more. It is important to note that while TM500 plug-ins can be used in the TM5000 power frame, the inverse is not true: TM5000 plug-ins cannot be used in a TM500 power frame.

Part of the repair/refresh process of any TM500 power frame requires the use of a Power Module Tester which (in conjunction with some basic test equipment … Read More »



Tektronix Type 106 Square Wave Generator Refresh

Posted by Shaun Merrigan in Electronics, Restoration, Tech, Test Equipment. Comments Off on Tektronix Type 106 Square Wave Generator Refresh

20th June

Introduced in 1966, the Tektronix 106 Square Wave Generator is a signal generator which can produce fast rise (<1nS @50 ohm loads positive or negative going) or high amplitude (120 Volts, high impedance load) square waves from 10Hz to 1MHz. It is used for oscilloscope calibration, risetime testing and for triggering extremely fast rise (<100pS) tunnel diode pulsers. The 106 uses a combination of vacuum tube and discrete solid-state technology. This is the sort of equipment that was used for development and testing during the NASA Apollo Program through the 1960’s.

The cost of the Tektronix Type 106 was USD 590 in 1966 or about USD 4900 in 2021 dollars. I was fortunate enough to obtain one of these units in decent condition and I was able to restore it to better than factory specification. What … Read More »