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.

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 »