How to fix BOSE Amplifiers

[CityofAngels]

After reading here that some were replacing all the amp chips and capacitors, I thought there must be a cheaper, better way to do this repair. For every component you remove, you run a very high risk of lifting the pad & trace connecting that component to the rest of the circuit. Older circuit board revisions have no resist since these are very low-cost amplifiers.

I had removed my passenger door amp over two years ago and it was sitting in a bag. This amp would "pop" then drop to half volume then eventually return to normal volume. So a month ago I pulled it out and to my suprise, it had a "wet" spot in the center ofthe board. The small green Nichicon capacitors had leaked their electrolytic onto the board. The repair was going to be easier than I thought.

Down to the local store to get 4 capacitors and soldered them onto the board. Put the amp and speaker back together. Plugged it in and it works flawlessly now. I turn the volume knob on the radio half a turn and this speaker is loud and clear. I ran it this way for 10 minutes and the problem has not returned.

While replacing all the amp chips and capacitors fixes the problem, it doesn't point to the actual problem. The green Nichicon metal-can capacitors are flawed. Replace all of these with newer, higher grade Nichicon caps or whatever brand you prefer. It is suprising that Nichicon turned out bad caps since the are generally a very good manufacturer.

I spent the day removing the other 2 amps and speakers. The woofer amp is a slightly different amp with one more pin on its connector and populated differently. Having seen the 3 amps at once, I see that the green capacitors show up in different places. The woofer amp has 3 green caps, that have leaked, in the center of the board. The driver-side amp has 7 green caps that have not leaked. The driver-side amp was the last one to die with a squeal.

I am putting a web page together with all the details so anyone with a few tools and a soldering iron can fix their amps.

Stay tuned!

 

[Edwardo]

Please let us know when you have a write up on the web. I know I have two speakers that need some repair. I would love to see how easy/hard your DIY project is.


Thanks!

 

[DutchBlackNsx]

What did you replace the chips with? I couldn't find any info on the chips, since they are customized.


Mich

 

[CityofAngels]

One amp(passenger side) used to have the volume troubles. One moment you have normal volume, the next you have half volume. I fixed that one by replacing the green Nichicon capacitors since they had begun to leak. It now works fine.

The subwoofer received the same treatment and now operates except it has some minor crackles every so often. I'm going to replace the FETs on this amp and see if that fixes it.

The driver's side amp developed a contant buzz/whine which was not fixed by replacing the capacitors. I think the failing capacitors wiped out something else. Working on the solution to this one.

If you want to buy Nichicon capcitors, go here:
http://www.mouser.com/nichicon/

They have a great web front-end and they are moderately priced. I ordered the "low impedance 105 degree" aluminum capacitors. I'll provide the run down of part numbers when I can confirm they operate normally. Use the "UPL....." part numbers as they appear to match the capacitors on the amplifiers.

There is another thread here in the forums dealing with fixing the amps that provided a link to a very good diagnosis of our amps.
I think this is the link: http://www.ojaspatel.com/nsx/ZR1BoseRepair/

 

[supergreen125]

cityofangels-
my driver side door speaker produces about half the volume of the passenger side speaker. any idea if this would fix that? also, i assume with the username "city of angels," you would be located in los angeles?? if this is the case, could i possibly bribe you into fixing mine???
lemme know.
mike

 

[CityofAngels]

Los Angeles, yes.

When you get half volume, all you need to do is replace the green nichicon capacitors. They slowly die and the result is the high/low volume problem. I had this problem and that is how I fixed it.

I'm deciding whether I should start fixing amps at a NSX local gathering or if I should finish up the web page for the DIY crowd. I'll do the web page and you folks post here if we should all meet up for a day of chatting and amp fixing.

 

[supergreen125]

why don't we try to coordinate it with one of the nsx meets?

 

[CityofAngels]

I have parts coming Monday/Tuesday which I'm anxious to get installed. I want to make sure I have all the amps fixed before I say it's a good solution.

Also, the less you use the radio, the less likely your are to cause more damage to other components. And if these amps are in ALL the NSXs, it would be good to know which model years have the afflicted amps. I'm guessing Bose improved the components at some point in time. Since it would cost $5 to replace all the capacitors in question, it makes sense to pre-empt the inevitable failure. Why damage other parts and cause other possible problems?

I'll post back when I'm fixed and bumpin with Britney Spears. (Yeah right, not in my NSX!

)

 

[CityofAngels]

Well I have moderatley good news. I fixed 2 out of 3 amps. The third amp is the one with the constant whine and no music playing. The whine doesn't get louder as you turn the volume up.

I have to pull the other door apart to try the bad amp on the known good side of the radio. Then I have to switch the amp into the good speaker/amp box and see if it is just the speaker has died.

Sorry, no "amp day" yet!

 

[CityofAngels]

Finally had a chance to test the bad amp on the good side of the radio and it IS the amp that is bad. The speaker is fine. Mind you I took the shotgun approach and replaced all the electrolytic capacitors and FETs but it did not fix the problem.

I set up a test bed and checked many of the relevant components and the results are not promising. Either the ICs(U1 and/or U2) or one of the small resistors/capacitors on the back of the board have died. I haven't been able to find a replacement for the ICs so it looks like I have to send this amp back to Bose. I hope they don't mind the "fix" I have attempted.

The other 2 amps are perfect with the new capacitors and FETs.

edit: If you call Bose at 1-800-231-2673(select option 4) they will take down your info and send you all the paperwork to have the complete speaker enclosure repaired for $79.25 which includes shipping. Patty and I were joking around and she said that the replacement cost from the dealers is up to $1,200 per speaker. I'm not sure where she obtained that price but $79 is far cheaper!

This is the address you receive with an RMA number:

Bose OEM Customer Service
145 Pennsylvania Ave, Room 1308
Framingham, MA 01701

[This message has been edited by CityofAngels (edited 24 March 2003).]

 

[agt86]

Hi ... I'm having the same problem too with my passenger door speaker ... hardly any sound till it warms up. I see that "CityofAngels" recommends calling BOSE. I'll have to try that. I did also find this place that will fix NSX stereos, $100 per speaker/amp. I was going to try that but I'll see what BOSE says as well. I called this place 2 days ago and they said their turn around time is about 3-4 days. http://www.carstereohelp.com/acura.htm

[This message has been edited by agt86 (edited 30 March 2003).]