Bose amp repair & system reference info
 

I just posted a large amount of detailed info on the Audio forum in reponse to the thread "Bose Information Request - All Gens, all trims" by studman. The info is what I've gleaned from my 1990 Bose sytem, and will apply directly to all 1989-1990 Bose systems and front amps only (I've not started on the rears yet). Included are Excel spreadsheets for a)list of electrolytic capacitors that should be replaced to get the amps working and b) an order list of replacment capacitors including Digikey.com part numbers. There is also a link to a 13 page Acrobat (.PDF) doucument composed by Gary James analyzing in detail the 90-91 bose amps used in Corvettes (very similar to Nissan Bose) and is a 'must-have' resource in my opinion.

Lots of you have ditched your Bose systems for aftermarket products, and I can see why. However, my Bose system was just fine for me - I just needed to get it working again. The info I've posted is far more comlete and accurate that anything I've seen posted previously after extensive searching of the archives.

Here's a link to the thread in the Audio Forum:

Bose Information Request: All Gens

I'll be posting a lot of additional info there soon also. Hope this helps some of you that would like to repair & retain your Bose stereos.

Thats fantstic info! cheers dude!

my front bose amps have:
Metal Cover/Shield Marking: "Sigma 711 Front" / "132035-S01F" / "3910/WS01'''
Circuit Board Mark: 3910WS01

My rear amps have "SIGMA 928 REAR" "142596-3104"

I repaired mine a year or so ago and they worked great, but now my front right has got a broken MOSFET... dunno how that happened?

Maybe post the info you've got in the audio forum here in a new thread and get the mods to add to the FAQ's?

I think studman had a FAQ sticky in mind for the Audio Forum when he did the original post back early this year- I've PM'd him about it - If no response, I'll approach the mods. Maybe put a cross reference in the 3rd gen FAQ or something. We need a database for this stuff. I'll get mine totally finished first, though - I want to make sure those 'better' replacement caps work right. I don't expect the rear amps to be much different.

Strange your '92 has the "Sigma 928" amps in the rear, but the "Sigma 711" front like my 1990. I've got both "Sigma 928" Front & Rear amps that I picked up in a lot of non-working Bose stuff off Ebay a while back. Those get fixed & documented next.

Yeah, i'm thinking some of the amps may have been replaced in Japan at some stage before the car was imported, so that could explain it..

Any idea which years had which model of amp? sounds like 89 - 91 had the 711's and 92 onwards have the 928's??

correction
 

awsm66? Are You around?

One of the things I'm trying to figure out. I think 91 and later had the plug* soldered directly to the amp as do the "sigma 828" amps; ealier models had wires soldered direct to amp.

* identical plug to 1 of the 2 twin 6-pin motherboard power plugs on the older style AT power supplies in personal computers.

rmax, with regards to changing out a transistor, the 711's have the numbers 98928 / 123534 on them, and the 928's have 99114 / 137110 on them, i'm gonna solder one of the 928's transistors onto the 711 board, as one is fried, do you think they're the same? or at least do the same job? Otherwise i'll try to find a new one, but i've had no luck at local parts stores..

Also, i've removed cap C110 from my 711 amp, and have forgotten which way round it went, its not marked on the board.. (yeah, stupid me) is the negative towards the outside of the board or the middle?

Cheers for your help!

Scott

Hi Scott! The C110 negative polarity is towards the U1 Op Amp chip (See Gary Jame's diagram pg 1) opposite side from the edge of the circuit board. When looking at the top of the cap, there will be an arc or color different from the rest. That marks the negative side of the cap.

As far as the transistors go, I have no idea. They are power transistors if that's any help. If it were me, I'd get on Digikey's site (www.digikey.com) and see if you can find an equivalent replacment before you swap for the Sigma 928 amp transistor - it also might be worth calling Digikey and ask if they can specify an equivalent replacement. The transistors on my Sigma 711 amps are marked "K688 9B4" so that gives you another equivalant number to work with. Here's another way to lookup specs and get equivalent parts:

IC Master

Gook luck,
Randy H.

Thanks for the info! I've now got the amp going again! I couldn't find any useful info about the transistors, so i just went ahead and swapped it, seems to have worked fine.

Another thing to watch, when i was reinstalling the speaker, it kept cutting out, and it turned out to be a dodgy connector plug (the big blue one from the amp to the car) so i removed it and just soldered the wires directly together. Problem solved.

Keep up the good work Randy!

The link is not there anymore. Could you post your how-to repair 3rd generation Bose Amp again? Thanks in advance.

My amp just starting giving problems.
The link to the post is not the correct one.
Would it be possible to repost this info???

thanks for the info it was on the mark