Tag Archives: restoration

Everything to Know about the Bose 901 Series IV Speakers & Active Equalizer Repair

Posted on August 10, 2026 by retrovoltage

A detailed look at the Bose 901 Series IV speaker system and Active Equalizer, with a brief history and explanation, plus repair tips and tricks, schematics, a discussion of the 5 different Active Equalizer versions for this generation, and a parts list with direct links to buy. Continue reading →

Posted in Audio, Bose, DIY, Electronics, Hi-Fi, Stereo, Vintage | Tagged , , , , , , , , , , , | 3 Comments

Everything to Know about the Bose 901 Series III Speakers & Active Equalizer Repair

Posted on July 31, 2026 by retrovoltage

A look at the Bose 901 Series III speaker system and Active Equalizer, with a brief history and explanation, plus repair tips and tricks, schematics, and parts list with direct links to buy. Continue reading →

Posted in Bose, Electronics, Hi-Fi, Stereo, Vintage | Tagged , , , , , , , , , , , , , | 4 Comments

1961 Audax CA-70 “Sonoteer” Speaker Refurbish

Posted on July 22, 2026 by retrovoltage

This set of 1961 Rek-o-Kut Audax CA-70 Sonoteer speakers got a full overhaul inside and out. Come learn about these interesting mid-century open baffle hi-fi speakers from a little known manufacturer and see how they turned out with detailed interior and exterior photos, and the original advertisement from September 1961. Continue reading →

Posted in Audio, Hi-Fi, Projects, Speakers, Stereo, Vintage | Tagged , , , , , , , , | Leave a comment

How to Buy Capacitors on Mouser.com

Posted on June 29, 2026 by retrovoltage

Learn about searching for electrolytic, film, and ceramic capacitors on popular parts house Mouser.com, with examples to help you get started selecting the right parts. Don’t risk counterfeit parts from 3rd-party suppliers – go right to the source! Continue reading →

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Philco 39-45 Retrofit to 40-201 Cabinet Vintage Radio Repair

Posted on January 16, 2015 by retrovoltage

A neighbor approached me with his family’s Philco 40-201 vintage radio to be restored back to working condition. It had sat for several decades, very well preserved, but ultimately needed some service after the years. Very unfortunately, however, the original … Continue reading →

Posted in Electronics, Radios and Tubes, Vintage | Tagged , , , , , , | 2 Comments

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 →

Posted in Audio, Electronics, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , , , | 8 Comments

EICO Stereophonic Integrated Amplifier HF-81 Repair

Posted on November 7, 2014 by retrovoltage

From the late ’50s, I had this nice example of an EICO HF-81 amplifier come through my shop. These are nice little stereo amplifiers with a built-in phono pre-amp and RIAA equalization and feature about 14W of power output per … Continue reading →

Posted in Audio, Hi-Fi, Projects, Stereo, Vintage | Tagged , , , , , , , , , , , , | 1 Comment

1931 Westinghouse WR-8 Columaire Antique Radio Repair

Posted on April 14, 2014 by retrovoltage

I recently got to work on another beautifully reconditioned Westinghouse WR-8 Columaire radio all the way from Bellingham. It was originally in for service with the SPARK Museum, but the repair technician reportedly suffered some health complications and was unable to … Continue reading →

Posted in Electronics, Projects, Radios and Tubes, Vintage | Tagged , , , , , , , , , , , , , , , , , | 3 Comments

1946 Zenith 6-D-029 Consoltone Antique Radio Repair

Posted on April 7, 2014 by retrovoltage

This was a very interesting Zenith tabletop radio from just after WW2, the 1946 Zenith 6-D-029 Consoltone mantle radio. This is one of the iconic “boomerang” dials Zenith produced for a couple of years after the war. A variety of … Continue reading →

Posted in Projects, Radios and Tubes, Vintage | Tagged , , , , , , , , , , , , , , | 3 Comments

1940 Philco 40-185XF Antique Radio Restoration

Posted on April 2, 2014 by retrovoltage

I had the privilege of working on a very well preserved Philco 40-185XF recently. These are top performing pre-war sets featuring 8 tubes, an RF amplifier front-end and push-pull audio output into a 12″ speaker. Definitely worth fixing up! This … Continue reading →

Posted in Projects, Radios and Tubes, Vintage | Tagged , , , , , , , , , , , , | 3 Comments