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November 7, 2018

Circa-1993 Bose Clock Radio Repair

Filed under: Uncategorized — admin @ 7:44 pm

One of the most interesting and challenging repairs to come my way at the recent Repair Café in Campbell River, BC was a Bose clock radio. This radio had no audio output other than a loud buzz from the speakers when turned on.

Bose Clock Radio, post-repair

These units can be disassembled in a series of steps. The primary step is to remove the four Philips-head screws on the underside, giving access to the main circuit board.

main circuit board

Most of the other cover components can be snapped into and out of place by pressing on tabs with a standard screwdriver. One of the first things I checked was the large primary power supply capacitor; that was fine and was not the cause of the problem. In this case, another symptom was that the LED display worked, but had a significant visible flicker at about 8Hz. After some tests of 3 electrolytic capacitors on the display circuit board, one turned out to be bad, and I replaced that with a known good 47uF 50V near-equivalent part. The replaced part is the grey capacitor in the lower right in the photo below. That fixed the problem entirely, and after reassembly, the radio is functioning normally – very impressive audio by Bose from such a compact radio.

replaced capacitor in display driver circuitry

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