Bose® 901 Series IV Active Equalizer #223227 Overhaul

Posted on April 24, 2016 by

From Rain City Audio:

This Series IV Active Equalizer, #223227, just came through for an overhaul. The owner reported it wasn’t making any sounds, just providing a DC offset on the output jacks which was giving his power amplifier some trouble. Time for some new parts!

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This equalizer is all original, including the LF353N op-amp chips which were the subject of a service bulletin due to their high failure rates. No wonder it’s having some issues by now!

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You can clearly see the residue left on the board from the electrolyte in the capacitor which boiled out and dried on the PCB.

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This one got all new electrolytic capacitors and new op-amp chips for proper operation, and now it sounds perfect on all functions and settings. Happy listening!

This entry was posted in Audio, Bose, Electronics, Projects, Vintage and tagged , , , , . Bookmark the permalink.

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