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

Originally posted in December, 2018 Early in 2018, I purchased an HP 3562A Dynamic Signal Analyzer for an excellent price on Ebay. The display looked great and it was physically in good condition. However, the unit failed the power on self test as follows: This error code indicates a ROM IC failure. HP3562A Diagnostic LEDโs…

Originally posted in March, 2018 I purchased a couple of HP 1340A XYZ Displays which I thought would be useful as troubleshooting aids and as graphical displays of CRT technology (oscilloscope clocks, and the like). Upon receiving them, they both worked, but careful visual inspection showed some potentially serious problems. I will document the repair…

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…

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…

Originally posted in August 2017 HP 8903B Audio Analyzer PCB Pad Replacement Visual inspection of my recently acquired HP 8903B Audio Analyzer revealed that the polymer pads on the bottom side of the main PCB were seriously deteriorated: Besides making an unsightly mess, this residue may form corrosive products which, over time, could damage the PCB.…