Do you have crackling or popping sounds coming from speakers? Strange UFO type noises? It’s not an alien that lives in your speakers. It’s capacitors that dried up in your Bose amplifier. Capacitors could be replaced to make your stereo sound brand new again.
When I bought my Mercedes 1992 500sel Bose amplifier was missing. Previous owner had aftermarket radio installed and installers butchered half of wiring in the trunk to get aftermarket radio to work. And on top of that they connected speakers wrong. 1992-1993 Bose amplifier sends full pass sound to front speakers, high pass to rear door speakers, bass to four rear deck speakers, and high pass to mirror mounted speaker. And there is a fader control that connects directly to amplifier. Stereo shop cut all wires to Bose, spliced wires from aftermarket radio into stock wires. Now, fader didn’t work, mirror mounted speaker didn’t work, full pass signal was send to all speakers, antenna didn’t work. Radio sounded horrible even though it was $500 Alpine unit.
Long story short, I bought Bose amp on eBay for around $120. Great deal I though. Once installed speakers started to make crackling and popping noises. I was very upset and after some research I found out that all capacitors had to be replaced. I opened up the amp, made a list of dried electrolytic capacitors, ordered and re-soldered them. And to integrate aftermarket radio with Bose amplifier correctly I soldered RCA pigtails directly into amplifier. On top I installed subwoofers with separate amplifier. My stereo sounded awesome :) Everyone who drove in my car always asked what system I had. When they were told that system is stock with aftermarket radio and subs they were amazed. I have very good ears and I need my sound quality to be perfect. S-class sound system is amazing if done right. Newer Bose amps 1994-1999 are slightly different in design and head unit controls fader and radio tuner. In pre-94 OEM stereos fader was controlled separately on the center console and there is separate tuner unit in the trunk for AM/FM.
To sum, if your Bose amplifier doesn’t work right, you have four options-rebuild it, buy new one at the dealer, buy used or rebuilt one, replace your whole audio system with new amps and radio. Rather than spending a small fortune for new amp at the dealer you would probably go with used one. But used amp might not work for long if at all. 25 year old capacitors are all dried up. Rebuilt amps are not cheap as well. Replacing whole audio system right way in W140 will cost small fortune depending what amps, speakers, and radio you buy. All you need is rebuilt factory amp and I advise aftermarket headunit. It will sound awesome.
I only rebuild 1992-1993 Bose W140 amps. 94-up amps are re-designed and don’t fail as often. They can be purchased used for around $250. Pre-94 amps are hard to find used and they all have capacitors that are already dry and will not last long. One of my customers purchased five used amps that kept failing until he mailed me his original amp to repair. Since then he never had any problems with stereo system any more. But lost quite some money on five used amps.
As of 2015 92-93 W140 Bose amplifier rebuild is $675 plus shipping
Below is the video of customer’s amplifier repair progress
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