Tag Archives: transistor

Bose® Active Equalizer Test Platform

Posted on April 13, 2016 by jwk

This project is going to take a while since I’m slammed in the shop, but I’m in the process of converting a Bose® 901 Series I Active Equalizer to  a test platform. With sockets for the transistors, and clip connections … Continue reading →

Posted in Audio, Bose, DIY, Electronics, Stereo, Test Equipment | Tagged , , , , , | 3 Comments

Bose® 901 Series II Active Equalizer #64364 Overhaul

Posted on February 27, 2016 by jwk

This Series II Bose® Active Equalizer came through the shop. It had suffered age-related failures in its electrolytic capacitors, and the resistors had drifted with age and moisture to produce the wrong curves. Fortunately, it’s nothing some maintenance can’t solve! … Continue reading →

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Assembling Transistor Radios in 1955

Posted on December 18, 2015 by jwk

Here’s a great documentary short from 1955 showing how portable transistor radios were assembled. It’s super retro! (2:35) Want to learn more about transistors? Just a few years later the US Information Agency produced an 8-minute short film about the … Continue reading →

Posted in Collections, Electronics, Vintage | Tagged , , , , , , , , , , | 2 Comments

Tektronix 575 Mod 122C Curve Tracer Restoration Project – Part 1

Posted on December 15, 2015 by jwk

A while back I picked up a Tektronix 575 Mod 122C transistor curve tracer from Craigslist and just started digging into it. With some encouragement from reader petepdx, I’ve started actually looking into fixing it up. (Click the photos for a much larger … Continue reading →

Posted in Commentary, Electronics, Test Equipment, Vintage | Tagged , , , , , , , , , , , | 16 Comments

Harmony H500 Solid State Guitar Amplifier Repair

Posted on October 10, 2014 by jwk

And now for something a little different, this time it’s a vintage guitar amplifier: the Harmony H500. The owner sent it to the shop out of the cabinet to be serviced since it quit putting out any sound. It’s a … Continue reading →

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New Toy: HP 143 Wide-Screen Oscilloscope Mainframe Restoration – [Part 1]

Posted on August 14, 2014 by jwk

At the risk of becoming a test equipment collector, I am picking up a few pieces of vintage test equipment that need some work, but will be very useful pieces of shop gear as well as interesting pieces of history … Continue reading →

Posted in Collections, Electronics, Hardware, Projects, Test Equipment, Toys, Vintage | Tagged , , , , , , , , , , , , , , , , , , , , , | 8 Comments

1958 Sony TR-610 Transistor Radio Repair

Posted on May 2, 2014 by jwk

I just finished a new project over at Rain City Audio – 1958 Sony TR-610 Transistor Radio Repair

This Sony TR-610 came through the shop to have its electrolytic capacitors replaced. It was a quick service and this iconic 1958 transistor radio came back to life just in time, only having missed a few Mariners games! With up-rated replacement capacitors and a new battery, it will last for a very long time.

Check it out at http://www.raincityaudio.us/blog/1958-sony-tr-610-transistor-radio-repair! Continue reading →

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