Just some notes after fixing the Bose amplifiers in my 97 SE. Over the last year or so, the front speakers just quit producing sound. In case you're experiencing these symptoms, you might try exchanging the amplifier circuit board from the 'dead' speaker to another corner to see if the problem is specific to the circuit board, or just a wiring or speaker problem. If you figure it's a circuit board problem, (it usually is), replacing the capacitors usually fixes it. I could not find anything visibly wrong with the ones I removed, so that makes this one of those projects where you have to replace them all and hope for the best.
First, I followed the basic procedure mentioned in the past on this ng by a couple of 3rd Gen owners - remove the speakers, remove the amplifier circuit board, remove the electrolytic capacitors (Nichicon brand parts), and replace them with the higher-quality Panasonic equivalents. All four amps are identical. I did not have the tools or knowledge to test each capacitor and replace only what is not functioning, rather I replaced them all and reinstalled the amps to see if it fixed it. It did, and now I know these parts will last much longer. In case you're like me, and you feel adventurous and want to fix yours (which is sensible if a couple of the speakers aren't making any sound at all), it will probably work for you too. Using .075" desoldering braid (.050" would probably work better), .050 lead-free solder, and a cheap 25w soldering iron, I replaced each capacitor. The parts are as follows, and probably* apply to all 4th Gens:
Board Volt. Data Temp Digikey Notes Location Rating Rating PN C7 16V 10µF 105°C P910-ND $0.09 C8 16V 47µF 105°C P914-ND $0.13 C16 50V 1µF 105°C P931-ND $0.09 C19 16V 820µF 105°C P10252-ND $0.55 Short Form Factor C25 16V 820µF 105°C P10252-ND $0.55 Short Form Factor C31 16V 10µF 105°C P910-ND $0.09 C172 16V 10µF 105°C P910-ND $0.09 C183 16V 10µF 105°C P910-ND $0.09 C203 16V 22µF 105°C P912-ND $0.10 Total x 4 amplifiers = $7.09. Now that's affordable.
*Probably, as in Bose customizes this stuff for every model car they install a system in. I have no way of verifying this is the exact setup for all '94-99s, but if you order, say, 20 of each of these parts you'll probably have everything you need.In case you're a real pro and want to change the MOSFETs too (I'm told they sometimes go bad), this is the info for them. But I didn't since I have no experience soldering ESD-sensitive parts, and it turns out they weren't necessary. Q1 60V 50A IRFZ44PBF-ND $0.95 Q2 60V 50A IRFZ44PBF-ND $0.95 Q3 60V 50A IRFZ44PBF-ND $0.95 Q4 60V 50A IRFZ44PBF-ND $0.95
Good luck, and have fun. If you're new to soldering, find a website showing how to do basic thru-hole desoldering and soldering. This site shows basically how I desoldered:
Even though it took me several hours to do this project, it's satisfying to get things working for so little. This will also work for fixing many dead home electronics such as network routers or PC motherboards.
Dave