EVOMMM

It looks like my amp is dying I need a factory amp for the bose system on my 2011 turbo S

PV997

I need one for my 997.2 TT also, so whatever EVOMM offers I'll go fifty bucks higher.

Haha. But seriously, mine is crapping out too with the usual symptoms that seem heat related but then starts working again after being off ~20 minutes. Have you tried the thermal paste or cap replacement in the megathread on the topic? Results seemed to be hit and miss which tells me that's not actually the problem.

Since it affects all channels I suspect it's the power transistor in the lower right corner of the voltage boost section seen in this photo.




This is from LarrySB's thread here where he describes the amp architecture:
https://rennlist.com/forums/997-foru...al-blocks.html

It's a 20 lead device and I think it may be of this family here:
https://www.digikey.com/en/products/...qRDkAnMxDsZxoA

Not trying to hijack your thread but I thought I'd throw it out there since I'm in the same boat. Anyone ever make any progress on this or able to get a PN for the chip in question?

EVOMMM

Haha if I pass on a deal I’ll redirect

EVOMMM

Any leads would be appreciated as well
also if you know a repair service that would work to

Wayne Smith

I did the thermal paste and replaced the caps. Worked great for 6 months. Then it started acting up again, but not as badly.

The other day I started the car but slipped with my left hand ... car started for an instant, shut off for an instant, and started again. All within less than a second. The amp came on fine, went off, and on the second start the amp failed. Came back on 5 minutes later. I don't know what this means, but it definitely points to a start problem IMHO. Lots of things are going on as that starter draws significant amps.

Bruce In Philly

2009 C2S 200K miles

My still has this intermittent annoyance... been this way for years. Did the thermal paste and the failure frequency dropped dramatically... then I replaced the power caps.... now it is worse. I don't know what to think. Someone here noted they spoke to Becker repair in NJ and they said it was some sort of signalling problem between the head unit and the amp. I am not sure anyone really knows for sure.

The only thing that I am sure of, for me, is the problem occurs only when I run the system on the loud side for some time, like 20 minutes or so... turn the car off like to get gas or wait for Her... won't turn on again for about 15-20 mnts.... signal to the sub is never interrupted and always works.

Peace
Bruce in Philly (now Atlanta)

EVOMMM

My problem exact yesterday I sat in my car with the radio on but down on volume but set at 3/4 max
waited a couple of minutes and it came back on its own

PV997

Thanks for the comments Wayne and Bruce.

The issue is common to all amplified outputs so it has to be something they all share. So that narrows it down to something on the front end before the signals get split up, or something in common to the power amplifier section. Since it seems to be the thermal sensitive my suspicion is that it's the latter since that's where the heat is generated due to the power consumption.

The five power amplifier chips on the left and top below each support two channels of sound. So if it's them they'd have to fail simultaneously which can't be happening. But as LarrySB pointed out the voltage boost section (which amplifies the voltage fed to these amplifiers) is common.



Bruce replaced the eight large caps in the middle and not only did it not fix it, but made it worse. That's what makes me suspect the power amp chip in the lower right. It's a high power amplifier but isn't used to boost audio frequencies but the voltage common to the five audio amps. See Bruce's update below, it's actually a voltage regulator from the same company which makes sense.

The audio amps are located next to the edge of the housing and have a good thermal path to the amplifier chassis and the cooling fins. But the lone voltage boosting amp doesn't. It has a poor thermal path that consists of a narrow post that must pull the heat upwards to the top of the housing where it travels across the thin metal wall over to the fins.




This would explain why new grease seems to help but doesn't fix it entirely. It's a poor thermal design and once the chip becomes marginal it's susceptible to overheating and shuts off. This may not be the exact chip used but I'm pretty certain it's from this family based on the form, lead count, and function:

Edit: Deleted link - see Bruce's comment below for the exact part.

it has built-in thermal protection which disconnects the voltage from the chip internals when it gets too hot. See the lower left in the chip's block diagram. (Edit: updated the block diagram based on Bruce's finding below).




I don't think anyone ever tried replacing it or at least it isn't mentioned in the megathread. We know these have been fixed by shops as others have sent them out and a there are a few shops online advertising repair of these amps. I'm willing to bet this chip is the culprit by I don't know the exact PN.

Here's a pic I found but it's the version with the thermal slug on the bottom. We'd want the version with the thermal slug on the top but I couldn't find a photo of it.




I've got a million things going on and probably won't get to this anytime soon, but if anyone does give it a try please post your results.

Edit: Noting that the post for the thermal path to this chip has a screw right next to it. A good coverage of thermal grease and ensuring that screw is sufficiently tight is probably worth a try prior to replacing the chip. That screw is probably there to pull the post down and ensure good thermal contact.

PV997

Hmmm, here's something interesting...

(deleted, need to research this more)

Bruce In Philly

I pulled the Bose amp from my 2009 C2S... here is the chip in question..... yes it appears to be alone next to that center screw.... it also is the least protected by heat sinks... at least its thermal protection is different from the others in that it uses that pad and the flip side of the circuit board has no metal press-plate as the others do.... so I loaded that green back plate with paste anyway.

If I did anything different, is that I now have better thermal paste coverage with that one chip... but time will tell if it did anything.
Bose Amp number: 997 645 444 04
Chip numbers: L5957PD 9DP836 (logo) V1 99 MYS

I never soldered this type of chip before... surface mount with tiny leads. Any tips of advice how to do this? I am nervous but that never stopped me.

Peace
Bruce in Philly (now Atlanta)

??? https://www.digikey.com/en/products/...5957PD/2214400 ???

PV997

Wow, great find. So it's actually a dedicated voltage regulator rather than a power transistor being used as a booster. Frankly that makes a lot more sense. I'm going to remove my links upthread so as not to confuse anyone. Kind off odd as the regulator has four channels but we have five power amps on the perimeter. But then there are eight caps too, not ten. Hmmm. It does have the built-in thermal protection so that mechanism is still plausible.

Unfortunately it looks like that part is a special order though they are only $5.10 each. Might be a minimum buy though as Digikey says we need to request a quote. There may be an alternative from the same family available. I'll poke around.

Edit: 585 in stock at Mouser, can ship immediately.

https://www.mouser.com/ProductDetail...LEmr7SFw%3D%3D

Bruce In Philly

UPDATE: Digikey won't ship single parts for this item. Another site wanted $40 for shipping this $6 part. All vendors I went to note this is some sort of special order part. WTF?

I will keep trying... gonna crack this thing.

Peace
Bruce

PV997

Bought several last night from Mouser at the link I added in my comment right above your comment. Got an email they shipped this morning. Several hundred in stock at about $5 each.

Eight bucks shipping from Texas which is outrageous as they could drop them in the mail but it is what it is.

Bruce In Philly

Thanx Jeff, ordered mine, $13 total... gonna be fun. I hope we cracked this although not a DIY for wrenchers... but if you get the part, you could have a local geek install it for you... There is only one electronics repair place left in Atlanta and the guy is booked out almost a year with work.... an older gentleman of course.

Peace
Bruce in Philly (now Atlanta)

PV997

Cell phone repair shops are usually set up to do this type of surface mount rework too, might be worth a try.