Category Archives: Electronics

Sony TA-5650 VFET Integrated Stereo Amplifier Overhaul

Posted on December 18, 2014 by retrovoltage

I recently got to work on a very interesting piece of vintage stereo gear from the golden age of hi-fi in the ’70s, the Sony TA-5650 VFET Integrated Stereo Amplifier. It’s a little rough, and while the power amp section … Continue reading →

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How Speakers Make Sound

Posted on December 3, 2014 by retrovoltage

If you’re looking for a great visual primer on how speakers convert electricity into the music you hear, check out this fantastic animated infographic by Jacob O’Neil at Animagraffs  How Speakers Make Sound

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Boxed Kit Amps’ Gobo Stereo Amplifier Build and Review

Posted on November 26, 2014 by retrovoltage

If you’re a subscriber to Nuts and Volts Magazine, check out my article in the December 2014 issue where I build, test and review the Boxed Kit Amps Gobo Stereo Amplifier, a great little desktop reference amp for any skill … Continue reading →

Posted in Audio, Commentary, DIY, Electronics, Gadgets, Hi-Fi, Projects, Stereo | Tagged , , , | 2 Comments

VD-1221 Replacement Substitute Diodes

Posted on November 25, 2014 by retrovoltage

VD-1221, VD-1212, VD-1220, VD-1222, and many other vintage multi-junction diodes probe to failure, which are used in bias and RF mixer circuits, can be easily replaced by series combinations of 1N4148 diodes for reliability and longevity. Continue reading →

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Vintage Schematic Mistakes

Posted on November 21, 2014 by retrovoltage

Every once in a while, you run into places where a drafting tech made some mistakes on the schematics. This one was a Philco 42-360 radio, which has the wrong tube called out in the tube line-up vs. the schematic. The … Continue reading →

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Harman/Kardon Control Amplifier A-401 Restoration

Posted on November 19, 2014 by retrovoltage

This little Harman/Kardon Control Amplifier, model A-401, just came through the shop for a full overhaul. It was in a pretty sorry state to begin with – one channel distorted, one barely gasping for air, and a world of scratchy … Continue reading →

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Toshiba 11H-540F Tabletop Transistor Radio Overhaul

Posted on October 20, 2014 by retrovoltage

I recently got to work on a little tabletop transistor radio from the late ’60s, maybe 1970 at the latest, from Toshiba: the 11H-540F. Not the catchiest name, but it was near the top of its model line-up featuring 11 … Continue reading →

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HP 143A Wide Screen Oscilloscope Mainframe Restoration – Part 2

Posted on October 15, 2014 by retrovoltage

Part 1 I’m continuing to work on getting my HP 143A ocsilloscope mainframe fixed up as a dual-trace X-Y display. A lot of the time has been spent on reading and researching, but I’ve picked up an important tool that will … Continue reading →

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Harmony H500 Solid State Guitar Amplifier Repair

Posted on October 10, 2014 by retrovoltage

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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DIY Replacements for Vintage Couplets and Printed Electric Circuits

Posted on October 9, 2014 by retrovoltage

Starting in the ’50s, they’d figured out how to start miniaturizing components. “Couplets” and “printed electric circuits” started showing up in equipment around then. These components were combinations of several resistors and capacitors in a single package. Like most components … Continue reading →

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