[RPM]

My speakers suddenly started crackling and moaning - even after the radio, and then the ignition, were shut off. I removed the fuse and all noise stopped. I fear the amp is shot.



Any ideas? How difficult/expensive is the original amplifier - where is it, under the pass. seat?

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[flash]

carefully check the power and ground cables to the amp - also carefully check the rca cables and their connections that go from the deck to the amp - this is most likely the problem - it sounds like an intermitent connection - could be a break in the line somewhere too

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[Steve Graham]

I had exactly this problem and removed the amp -- however, my amp turned out to be a non-standard one: a 928 part. It was in the passenger footwell, accessible after removing the wooden floorboard(!) No guarantee yours is the same.



Now I need to turn the stereo up to 50 instead of 30 to get the same volume, but I can live with that! I guess the amp was for the days when a stock head unit wasn't very powerful.

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[RPM]

OK. I did some troubleshooting/investigation yesterday. All the connections seem fine. I have two amps, one under each seat (option code 490 I guess - 10 speakers and 2 amps). The front channel is the one malfunctioning.



Before I pull apart the interior I would like to try and get three questions answered -



1. Are the amplifiers identical and does anyone have a part #?

2. Which one controls the front channel - driver's side or passenger's side?

3. Are the 6 hexagonal bolts what holds the seat down?



Also - does anyone have a 968 schematic in a PDF or similar doc?

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[flash]

the schematic, along with the rest of the manual, and the 4 50 page supplemetns i have, will be available here as a pdf download by wednesday

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[RPM]

Thanks Bob. That will be a great addition to the site. I am starting to realize that each 968 seems to have been cobbled together with whatever Porsche had nearby the assembly line. Trying to get a fix on the exact replacement amp is and adventure. The schematic might answer the front channel/back channel question - If it shows the difference for w/490 and w/o 490.

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[Greimann]

Here are several pages from the wiring diagram that show the stereo wiring. (about 2 meg download)

968_Radio_Wiring.pdf Size: 1.92 MB  Downloads: 89

According to the PET the amplifiers are the same part number: 944 645 301 00

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[RPM]

Perfect! Thanks.

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[flash]

cool - thanks dave



ralph - yes, i thought it would make a good addition too



if you have more questions, please feel free to call me at the office - if you don't still have the number, send me a pm or email and i'll give it to you - it may not be the amp itself, but rather a connection to it - we can do a point to point diagnosis over the phone

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[RPM]

The plot thickens: My 93 does not match up with the 94 schematic. In 94, according to the schematic, there is one amp under the pass seat that powers the front channel and the back speakers are self-powered.



Just for clarification this is the 490 option with 10 speakers - three in each door (tweeter + two under armrest) and two in the rear (a main bass speaker and another small one).



My car however has two amps, one under each seat. I suspect that for 94 the 490 option changed to the layout reflected in the PET. That is the thing about 968s - supposedly little changed over 4 years, and yet lots of little things changed without announcement.



After much experimentation and trouble shooting this afternoon I have discovered that:

1. All of the connections and fuses seem intact

2. The amp under the passenger seat powers the rear channel

3. The amp under the driver's seat powers the front channel



Since it was the front channel that was out, I pulled that amp and will check with Sunset for price. The part # matched Dave's post.



The good news is that I have the rear speakers working so at least I can listen to the news on the way to work the next few days. The bad news (in addition to whatever Sunset wants for the amp) was that I started my investigation on the pass side - lots of wasted time and effort.



Thanks for all of the assistance and I'll keep updating as changes occur - as if anyone actually cares about my stereo system <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[Greimann]

Just out of curiosity, why don't you chuck the whole thing and get new, aftermarket head unit and amps?

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[RPM]

Good question. I like OEM and try to stay with it whenever possible. Sunset has the amp for $162 (along with an estimated 1 month wait on the thing from Germany!). That will be a much cheaper solution than a whole new setup.



If I do upgrade everything in the future it will be to go to a CD/DVD/NAV system that currently would run around $2k. I'm going to wait a bit.

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[flash]

did you swap amps to test that it was in fact the amp and not the connections or cables?

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[RPM]

did you swap amps to test

A very good question!

Yes I did.

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[kamran haghbin]

hey bob i think the front and rear amps may not be the same amp, so swapping may not be a good idea. well if you want a front amp, I have the front amp still mounted in my car. I switched to an aftermarket system when my rear amp dies, so if you want a front amp just e-mail me and id be more than happy to pull it out for you once this rain stops.

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[flash]

maybe not, but they probably have the same connections and such and could work for a test

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