M35 Bose Amp 5.1CH, Dead

[loystock]

I have an 06 M35 Sports with 72k miles. The Bose Amp 'died' (all speakers inop) when trying to hook up the Droid cell phone (other cell phone worked before). Really weird. I checked all fuses and power to the Amp - all OK.

I pulled out the Bose Amp, Model No 28061-EH11A and opened it up. The circuit board P/N: 270624-003 Rev.00. Unfortunately, most of the circuit components (except for capacitors and regular transistors) have been deliberately covered with dark coating. So it's really difficult to trace the circuit and troubleshoot.

Has anyone encountered this problem? I searched the forum and didn't see anything related to my problem. I will hook up just the main board to the car tomorrow and do some more tests.

If I can't fix it, these are the options I'm looking into:-get an OEM replacement part (from IoS or Crutchfield)send it to "carstereohelp.com" or equivalent for repair (@ $200).-get an aftermarket replacement part

Any other suggestion?

[the converted]

If you only had this problem right as you tried to sync the droid, I'd guess that it might have been a crash of sorts. Disconnecting the battery might reset it.

[loystock]

Thanks. I'll give it a shot. If problem remains, I'll do additional board testing and then contact JoeT of IoS for replacement amp.

[the converted]

There is also a sponsor at the top of the forum that does repairs. I do find it quite strange that the whole amp went dead at once as you were syncing the phone.

[loystock]

Disconnected the battery overnight and restored everything this morning - same problem. Radio, CA and Navi are working but no audio. Having owned Nissan/Infiniti cars for a long time, this is the first time I have a problem with amplifier. Really strange.

[the converted]

I'll take a look and see if there are any strange fuse locations in the FSM or any other funny business that could be going on.

[loystock]

I checked all the fuses related to audio/amp and they are all good. I verified power to the amp connectors - Pins 16 of J107 (ACC power) and Pins 50 & 51 of J108 (Battery power) are all good. I even used the built-in diagnostic and it showed the Amp is dead (gray color). All other control units in good states. Because of that failure, you cannot use the Speaker Test in the built-int diagnostic.

Aside from the dark coating on the PCB components, the casing of the amplifier boards serves as the heatsink to the power transistor. So there is a possibility of 'frying' them if power is applied with casing removed. Even with the dark coating, I was able to identify 2 power-related components on the board - 1 is a Zener diode for Transient Voltage Suppression and the other one is 5VDC regulator. I'm trying to come up with an improvised heatsink for the 'live' test.

I also contacted Joe of IoS and gave him the VIN number in case I need a new amp.

Thanks you for your help.

[loystock]

I got lucky and got one from eBay for @ $24, including shipping. What I got was the upgraded version 28061-EH11C, and worked perfectly. It's the best deal I ever got from eBay. The discounted price of the Bose Amp from IoS would have cost $480 while repair at "carstereohelp.com" is @ $200.

I have identified the problem with the amp (a 5VDC regulator) but the problem is that you cannot buy the part from electronics parts store while online, it only available wholesale from Asia and in bulk of 100 items or more.

[the converted]

Got a part number or anything? I have a pretty bad a** electronics store near me, and I think I'm swinging through there in the next week or so.

[loystock]

It would be great if you could get those parts for me:1. P/N: LM2940T -5/0 - This is a 1 Amp, Low Dropout Voltage (0.5VDC) Regulator with 5VDC regulated output, by National Semiconductor.2. P/N: SM5A27 - Transient Voltage Suppressor with Vbr=27VDC (Breakdown Voltage) by Vishay General Semiconductor.