doclouie

Bruce, was the last time the audio cut out happen before or after the hard drive switch?

Bruce In Philly

After... the drive had nothing to do with this.... so it would appear.

Peace
Bruce in Philly

doclouie

I will be searching for a power wire by the amp when the car is on next to rule that out. I have never seen the fan actually turn on.....ever.

Wayne Smith

Got out today. The stated distances are rough ...

Started with a 40 mile drive down the coast at 65F. Stopped for gas. Started and no audio.

Drove 200 feet to a meeting point. Motor off for 5 minutes. Audio was back.

Drove inland and 40 miles at 90F. Motor off. Lost audio.

So I did a soft off (quick tap of the power button such that the amp will turn on at next ignition on) while driving. Continued driving for 5 minutes. Powered the radio on. No audio. So I tried again and still no audio.

So I held the button in longer to create a hard power off (radio will not turn on with the ignition). 5 minutes of driving later, when I turned it back on I had audio. Still 90F temperature. No ignition off required but the amp was on a hard off state. Don't know if the 5 minutes was needed.

The above is a single data point and not scientific.

I still believe this is a CAN Bus start up problem and the amp is self retiring due to bus errors. I'm wondering if we are fighting connection problems between units. But to be truthful I'm merely guessing at this point.

I just don't experience this enough to analyze it. This is the first time I've seen it twice in a day.

larrysb

The amp isn't really on the CAN bus. Power-on, audio, special effects, fader commands, all come in digitally from the head unit on the two-fiber optical channel. (MOST bus).

Inside the amp is a optical port, a MOST transceiver chip, then it goes to an ST-Micro CPU to run the software layer on the MOST bus, as well as control the amp, and a SHARC DSP does all the audio decoding, filtering, Dolby/DTS, subwoofer channeling and feeds all that to several DA converters for the channel amplifiers. The power amp section is 5 class-D chips and a voltage up converter to boost 12v up to about 40v dc.

It is really hard to say what is going on. A prime suspect is the DC-DC booster that provides the power amp chips with higher voltage DC. That should take just a single digital signal from the CPU in the amp to make it turn on create power to run the power amp chips. But it could be other things.

Hard to tell without having a failing one setup on a test bench.

Wayne Smith

Damn, throw away my thoughts!!!

But I'll hang on to the "This is a power on start up problem" idea.

Thanks for the better information and correction.

larrysb

The amp is connected to the car's data bus, so that it can send diagnostic messages and get coded when a dealer has to replace one. The same hunk of amp hardware is used in multiple vehicles. It has to be coded on installation so that it "knows" what kind of car it is in and the features are configured correctly. But all the entertainment operation is through the optical port. The other little secret is that there's an ambient-noise sensing microphone in the steering column surround that goes straight to the amp. The DSP in the amp is supposed to measure the noise and adjust the volume and EQ for driving conditions.

Wayne Smith

That EQ feature has never done anything in mine whether I turn it on or off!!!

I've read CAN Bus books (always used RS-232 with my own protocols in my industrial controllers). I just kind of figured with decentralization anything electronic on a car was tied via CAN Bus.

I guess it's time to pick up a good book on car audio. My time goes back to 8 track players!!!

Any suggestions?

BucketList

More data. This happened to me also after a long drive. Stopped for gas, no audio except sub. Kept driving and tried Waynes hard power off. Left it for 10 minutes, still no audio. Parked at destination for an hour, came back and audio is good. Drove back home and audio is still good. This has only happened to me twice in the last 2 years. The fact that the sub is working tells me the audio signal is moving across the MOST bus since the main amp has to decode and send to sub amp. Larry might be on to something with the power supply. They are very difficult to troubleshoot when the issue is so intermittent. Do we know for sure a new amp fixes this issue?

Bruce In Philly

Update:

A new issue.... I just had my first re-boot. Oh Oh...... I started the car from cold, music playing, about 20 seconds later, I got silence and the Porsche crest. Re-boot. This never happened before. I have randomly seen the Porsche crest on startup.... rare but happens.. but never a reboot while operating. Note, I have replaced the disk drive with an SSD months ago with no issues.

Regarding the cutting out after a re-start.... since I did the thermal paste thing.... I almost never get the cut out anymore... just don't . Very rare. It did happen the other day just shortly after I started my car.... I drove to the stop sign, and stalled the car... yes I really did....whattadope... re-started and the PCM was dead except for the woofer. This never happened when cold like this so I always assumed it was thermal. Maybe the stall represented an inappropriate shut down and the there was junk in the commline... who knows...

Peace
Bruce in Philly

BHMav8r

So my problem is that the audio wont come on when its cold outside.

Used to be really cold like 20's. originally it would sound like a poltergeist when you started the car.
Then it just wouldnt work.
Over a few years its creeped to not really cold, like low 50's.
Warmer temps help, Drive somewhere, come back out and it works.

Anybody else?

BTW my heat doesnt work either.

Wayne Smith

I'm with Bruce on comm line errors but have been told the amp doesn't share the CanBus. So what do I know?!?!

Heater doesn't work but fan does implies the thermostat is stuck open or has been removed. You don't want to drive that way. But if you mean the fan doesn't work that's something else.

997Ferg

Hey everyone, glad to see this thread and find I am not the only one. My .2 turbo has had this issue since purchase (a month ago). I figured since the only sub issue happens on restart it was a software thing not thermal, but I will say it usually happens after driving for a while (so who knows) Such an odd issue that is so inconvenient.

I tend to turn off the PCM for 10/15 min and everything works again. Might end up going to a carplay head unit like my old .1 C4S and be done with the issue lol. I’m in for any more updates.

Wayne Smith

Just musing here. I'm ignorant on the steps to replace the head unit. Never intended to do this so I haven't paid much attention. So from the mind of the unknowing ...

When you replace the head unit do you replace the amp as well? And the speakers? Or do you use a MOST adaptor and keep the amp? And if you keep the amp and the power on problem goes away is the amp still to blame?

GTSpure

I think Porsche want us to hear less music and focus more on the driving and noise of the exhausts LOL