Shaun Merrigan

Classic Electronic Restoration, Vacuum Tube Audio, Technical History, Photography

Tag: HP 70000 MMS

HP 70001A Power Supply Refresh

15/11/2025

Failed Component Spotlight, Hewlett Packard (HP), Restoration of Classic Electronic Test Equipment

Originally posted in November, 2023 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…
Analysis of Sprague 672D Capacitor Failures in vintage HP Test Equipment

14/11/2025

Hewlett Packard (HP), Restoration of Classic Electronic Test Equipment

Originally posted in November, 2023 This post documents my investigation of Sprague 672D Electrolytic capacitor failures in HP 70000 MMS test equipment. Background Introduced in 1986, The HP 70000 Modular Measurement Sysem (MMS) is a highly configurable test equipment system comprising spectrum analyzers, DVM, power meter, oscilloscope, signal generators, phase analyzer and more. I have…

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