Repairing a vintage 40-kilovolt xenon lamp igniter

Ken Shirriff writes: What do xenon lamps and the invention of radio have in common? The box below is a 1960s German high voltage unit that CuriousMarc obtained as part of an auction. After some research, we determined that it is an Osram1 igniter2, which generates a 40-kilovolt pulse3 to ignite a xenon arc lamp. […]

Understanding and repairing the power supply from a 1969 analog computer

Ken Shirriff writes: We recently started restoring a vintage1 analog computer. Unlike a digital computer that represents numbers with discrete binary values, an analog computer performs computations using physical, continuously changeable values such as voltages. Since the accuracy of the results depends on the accuracy of these voltages, a precision power supply is critical in […]

Teardown of a Marconi 2305 modulation meter

Kerry Wong did a teardown of a Marconi 2305 modulation meter: I picked up a Marconi 2305 modulation meter off eBay the other day. As the name indicated, a modulation meter is used to measure the modulation characteristics of a source signal. The Marconi 2305 is capable of measuring amplitude/frequency and phase modulated signals from […]

HP 8566B Spectrum Analyzer “YTO unlock” repair

Kerry Wong did a repair of an HP 8566B Spectrum Analyzer “YTO unlock” and documented the repair process on his blog: While I was making a video on how to use HP 8671A as the frequency reference for an improved version of my simple DIY tracking generator for my HP 8566B spectrum analyzer, my spectrum […]

Repairing a 1960s mainframe: Fixing the IBM 1401’s core memory and power supply

Ken Shirriff wrote a great article describing the repair process of  the vintage IBM 1401 mainframe computer: The problem started when the machine was powered up at the same time someone shut down the main power, apparently causing some sort of destructive power transient. The computer’s core memory completely stopped working, making the computer unusable. […]

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer from The Signal Path: In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible […]

Teardown, repair and experiments with a Tektronix RSA 6114A real-time spectrum analyzer

Tektronix RSA real-time spectrum analyzer teardown from The Signal Path: In this episode Shahriar attempts a difficult repair of a Tektronix RSA real-time spectrum analyzer. This well-equipped instrument reports several error messages during startup POST including LO Unlock as well as Signal Path failures. The service manual of the instrument does not provide any detailed […]

Sony TC-252 reel to reel player restoration

Dilshan Jayakody has written an article about Sony TC-252 reel to reel player repair: As a first step of the restoration we remove the LA4440 module attached into that recorder and rewire the player with original wiring layouts. After rewiring we check all the transistors in that player and find-out that the couple of 2SC634 […]

Repairing a Marconi Instruments 2955A Radio Communications Test Set, part 1

Mikko has written an article about Marconi 2955A repair: First off, I decided to see what was the deal with the CRT. I have never worked on CRTs before, I have understanding of how the picture is formed by steering the electron beam using the deflection coils but that’s about it. I know a charged CRT […]

Repairing the TUNE capacitor on the Heathkit HL2200 (SB-220) amplifier

KA7OEI  did a repair on his amplifier.  He documented the whole process on his blog: Earlier this year I picked up a Heathkit HL2200 amplifier (the newer, “brown” version of the SB-220) at a local swap meet for a reasonable price.  What made it particularly attractive was that it not only had a pair of […]

Radio thermostat CT-50 review and install

Felix of LowPowerLab writes: I mentioned before that there’s added support for HTTP requests in the gateway interface. That allows using things like wi-fi thermostats, and this story is a review of how I did just that. I wanted to integrate the home thermostat into the Moteino IOT Framework Gateway and be able to control […]

Recovering a bricked CC3D board using a Bus Blaster

Angus describes on his blog how he used the Bus Blaster to recover a bricked CC3D board: A few months ago I went to upgrade my OpenPilot CC3D board an something went amiss and I ended up trashing the bootloader. I didn’t have a SWD dongle to reprogram it with so its been collecting dust. I just […]