mcfisticuffs

No solution, just a data point:
997.2 C2S 30,000 miles, PCM 3.0. Forget which Firmware version, but I did check at the time, and it was the latest.

I let my car sit for ~2 hours in the rain one day while I was in the gym. When I returned, the PCM would not produce ANY sound (AUX/CD/FM/AM/IPOD) on ANY setting. Persisted for the remainder of the day thru half a dozen restarts.

Next day, worked fine. No issues since.

Bruce In Philly

Good stuff all, thanx.

For the 997.2, the amp is under the passenger seat.

Regarding the PCM headunit doing the overheating, yes possible, but I doubt it as I can hear the fan in it run once in a while... the unit does not "drive harder" when you turn up the volume as it is done in the digital domain... the connection to the amp is fiber optic as it is to the sub (I am not 100% sure about this as my memory ain't so good anymore). When the sound cuts out, all functions on the PCM work.

The cutout occurs only when using the unit for a while, then mute, then sound won't return. It has always worked when turning on from cold. This problem occurs only after continuous use.

Yea, I bet it is the amp. I will look on eBay for a used unit and see if I can see a fan, or what looks like fan vents.

Peace
Bruce in Philly

I think this is the unit.... doesn't look like it has fan vents....
http://r.ebay.com/7r7CQp

Petza914

You sure about both the connections to the amp under the passenger seat and the amp to the sub being fiber optic. In the 997.1 only the connections to the main amp in the frunk are fiber optic and those to the rear subwoofer enclosure are regular, and there's a small regular amp inside the rear enclosure that powers those subs.




Main connector to the sub enclosure



OEM subwoofer amp (resides inside the sub enclosure)



OEM connector to Sub amp



Internals of upgraded Sub enclosure

Bruce In Philly

The 997.2 PCM 3 is completely different animal. The head unit plays 5.1 DVD Audio discs, sends this 5.1 signalling to the amp under the seat in digital format. I am not 100% sure it is fiber to both amps but that is what I remember my installer telling me. (I believe it is daisy-chained back to the sub-amp) This PCM3 unit came in two flavors, premium (what most of us have), and some basic unit that is stereo only... but they are the same head unit just coded differently to behave differently.

If a 5 channel analog signal is passed head to main amp, it would have to pass 10 conductors for the 5 channels and the jack on the device is far less than this. I am 99% sure this is not the case.... I know for a fact, 100%, that there are no pins passing analog signals out of the head unit, with the premium sound 5.1 package, because you can't just swap out the amp.... the amp is receiving digital signals from the head unit. You can have the dealer recode your PCM3 head unit to activate another set of pins, left empty, to turn on classic analog stereo output pins. Then you can change the amp but you won;t have 5.1 DVD capability and the sub goes silent.

(I had the whole system replaced with an Alpine head, JL Mosconi amps and they couldn;t get the whine out so they gave me my money back and reinstalled everything... at this time they told me about the fiber links ... I think.)

Anyway, the reason I believe it is the 5 channel amp under the passage seat failing is that the head unit it not producing heat when you turn up the volume, the volume is in the digital domain and the digital signal is passed to the amp that does all the decoding and amping. I am not 100% sure if the digital cabling is fiber optic or not.... not really relevant since it is a digital signal.

BTW, get a copy of Queen's Night at the Opera in 5.1 DVD A and pop it into your car... wow, really cool!
BTW2, I find it really interesting that Porsche decided to give us 5.1 DVD Audio when it is a dead format and there was so many more relevant tech they could have given us.

Peace
Bruce in Philly

alexb76

Cool, what about playing a digital format with 5 channels, does it decode and do it in 5 channels as well?

Bruce In Philly

Just pop a disc in to see if if will play.

The PCM manual and one of the PCM3 screens show you the formats that it will play.... really odd in that plays some hardly used and dead formats such as DVD A and Meridian's audiophile encoding.

Peace
Bruce in Philly

WatchC

Guys I have a 997.2 with PCM3.0 . The unit works when I first get in the car after it’s been parked overnight but then freezes after around 5 mins . It still plays sound tuned into a radio station . The display is fine but I am unable to make any selections work or turn it off . The volume will not adjust , I am unable to select Nav or map or answer a call . Since the last couple days the Bluetooth isn’t working either . Anyone have any experience if this ? Im thinking it’s not the amp as the sounds works . Sometimes after a longer journey the unit will suddenly start working again but I havnt tested this a lot as I don’t do many long journeys ! Maybe it’s an over heating issue 🤷🏼‍♀️

as an addition a few years ago driving in torrential rain the sound went very muffled and took a while to correct itself . Wondering if that could have been the start of a problem .
hope
one if you guys might have an answer !