dgeesaman

iTrader: (10)

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
by some 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

(An easier-to-read chart is here)

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:
http://www.epemag.wimborne.co.uk/desolderpix.htm

and this shows how I soldered:
http://www.antex.co.uk/pages/paper3.htm

There are many, many, other sites showing the basics of soldering, and
honestly it's daunting subject matter. But what was on those sites was
enough to get my stuff fixed.

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