Rather than a question I am writting this thread to encourage those with bad Bose speaker amplifiers to repair them.

You can go out and pay the $150. each to get replacements or you can just fix them yourself for pennies and about two hours total time.

I had two bad amps on my 94 C-4, (left front and left rear) I was pretty sure that it was the amps because I could hear music coming from the speakers very softly at full volume.

I am not a mechanic nor an electronics tech. I did read numerous threads on how to repair them. The thoughts of paying large amounts of cash to buy new circuit boards was not at all appealing. I figured I can't break them any worse than they all ready were. I took an old junk circuit board and practiced de-soldering and soldering, had it down pretty good after a half hour of playing around on a junk circuit board.

The first step in the repair is to remove the circuit board to be repaired from the speaker. Every one of the Bose speakers has it's own separate amplifier mounted with the speaker.

Open up the amplifiers metal holder and study it for a few minutes. You will see that every capacitor has been identified with the letter "C" and the number.

its very easy to figure out. You will need a de-solderer tool and a good soldering gun.

I am attaching a list of the capacitors that need to be replaced. Most of the times it is the capacitors that go bad. It is just as easy to replace them all at once instead of doing just one. (I found C-7 & C-8 were the burnt ones on both of my Amps) Don't be afraid to try it.

I am a 63 year old retired Cop, and I was able to amaze myself and repair both amps in two hours.

I am providing a segment from another blog that list the capacitors you will need, they cost only pennies each so I ordered a dozen of each to have extras for the future.

I ordered through "MOUSER". and had them in about a week.

The only thing a novice needs to know ahead of time is the difference between the positive and the negative side of the capacitor and the boards terminal. You can tell by looking at the circuit board with the capacitor removed. the capacitor location is indicated with a white circle, the circle has a line through it, the smaller section of the circle it the negative and the large portion of the circle is the positive.

Most capacitors have a stripe on the side of it indicating the negative post. Also all capacitors will have a long and a short lead, the long lead is the positive and the short lead is the negative. I know it sounds complicated but it is a lot easier to do than to explain.

I am available to help anyone that needs it. Like I previously said, It is already broken, so give it a try. I was really pleased with the results.

Best of luck
Woody

Part Number Total Qty BOSE Original

EEU-FC1C821S 2 820uF 16V 820uF 16V C19,C25

EEU-EB1H100S 3 10uF 50V 10uF 16V C172, C183, C31

EEU-EB1E470S 2 47uf 50V 47uF 16V C7, C8

EEU-EB1H4R7S 1 4.7uf 50V 4.7uF 35V C203

EEU-EB1H1R0S 2 1uF 50V 1uF 50V C16 C150

Good info! I've been thinking about doing this for several years, just never got around to it.
Looking at your list it appears there are 10 capacitors you replaced?
What type of gun did you uase?

Joel

Great tip Woody!

I did go through and add some line breaks. It is so much easier to follow steps when the text is broken up a bit, vs one long paragraph.

A few thoughts, too:

I am a huge fan of the Weller SP80 soldering iron. It's about $35 and is available at many hardware and electronic stores. It simply ROCKS. Hot, fast and accurate... also very durable.

where can one get the de soldering iron ????

It's not an iron!

You use an iron, sure, but the desoldering tool is actually a little vacuum... it can also be done with a steel brush.

But the tool itself looks like a fat magic marker, with a spring loaded button on top... push down and that moves the piston down the chamber. the end of the piston has a pin to help clear this nipple thing at the end.

Push a button, the plunger with piston comes up, sucking the solder with it. These are often times called a "solder sucker."

http://www.meritline.com/desoldering- ... JD0rZKwpbUCFcef4AodFDoAqA

Great tips and parts list!

I finally got off my lazy side and decided to start on this repair. I chose to try the rear amps first, much easier to remove and replace. My capacitors were different than the OP's size, different uf ratings. After some reading it appears there a couple of different boards for the C4's

I ordered from Digikey, for me their web site was easier to navigate.
Got the rears hooked up today and the sound is much better, no more whine and squeal. I've still got to modify the metal enclouse box the amps sits in. The two new big capacitors are slightly longer and don't allow the top of the box to seat fully.

In case anyone needs more part #s:

560uf: #P11202
47uf: #P10340
10uf: #P10316

I plan on doing the fronts next week
Thanks to the OP for his post!

Joel

one other element of fixing these amps...

Bose still replaces them... they are available, but only as GENERIC Bose amps, not tuned to a specific vehicle.

I read this several years ago, but don't know from where it came... but it does make sense.

It is best to fix these than replace with the generic.

Bose also offers drivers, too... but for that, you can actually fix your existing drivers.

1. Go to a site called www.decware.com and buy the proper sized rubber surrounds.

2. Replace same.

3. Using basic acrylic glue (3 parts water, 1 part glue, IIRC), brush onto the paper cone. It will stiffen the cone and improve its long term durability.

Decware also suggests using their glue straight (not diluted) on the cone.

They also have some seriously kick-ass speaker enclosure build kits...

the exact link:

http://www.decware.com/newsite/diy/decware/Speaker_Repair.html

That's good info Andy, thanks.
I saw that Bose site several years,just more money than I'm willing to pay for this system. If this cap replacement dosen't hold up I'll just go with a later model F-body non-Bose with the disc player and replace the speakers.
But for a few bucks it's worth a try. Just more labor wasted, but my time is pretty cheap anyway!

Thanks
Joel

I finally got the fronts installed today, somewhat happy with the results.
The cap replacement did cure several problems. There was a loud "pop" when the radio was turned on, that's gone. And the whine and whistle is gone. Before there was almost no sound from the front speakers, fixed that.
I would rate the sound now as just decent. But, a lot better than before.

Joel

All of this was a great help. I am half way through replacing all the parts on my front driver side amp. Does anyone know what C206 is? I broke it off the board while I was trying to remove the hot glue and I am not sure what it is. I believe it's a .47 uf cap but most of the numbers came off with the glue.

Thanks,
Charlie

I don't remember a #206? Are you sure it's not C203? That should be a 4.7uf 35v.

Joel

It's not an electrolytic cap like all the other ones. It's a small white, square component. The top of it said .47J but all the other markings on the side came off with the glue. It is located directly behind the 6 pin connector for the power and signal harness.

The sides of all the other similar components say 50-MMK____ with 4 numbers after the letter K.

Thanks,
Charlie

OK now I got it. On my 89 this was #172. I broke one also.
The markings on mine were >47J 63. On the other side was MMK 8741. Went all over town trying to find someone that knew what the markings were, no luck.
On the Digi-Key site they have a on-line chat, very nice folks. I ordered and used this one.

Joel

http://www.digikey.com/product-search ... yWords=399-5442&x=18&y=13

Yes that looks like it. I really appreciate all the help.

Charlie