Mitsubishi Eclipse Factory System

Hi all! Can anyone please give some advice to an amateur? I have a 2002 Mitsubishi Eclipse GT with a stock Infinity stereo system. It's the 4 CD changer, with am/fm, cassette, and 6 speakers. Last week, all the speakers started cutting out intermittently. It seemed to be random, not related to speed, engine RPM, rough roads or anything noticeable. Well, now it's constant. I'm not getting sound from any of the 6 speakers. Everything seems to work mechanically, I can change stations, switch between the 4 CD's, the remote display in the dash shows what's happening, but no sound. I've been reading some other similar topics in the forums that have given me some ideas of things to check, but I haven't found a solution yet. Heres what I've checked so far: 6 pin plug from the H/U to the amp: I have continuity on all 6 pins and on the outer connector. (I think it's a gounded shield.) When plugged into the H/U, one of the pins checks 12v, one is ground, and the sheild is also grounded. There is no measurable voltage on the other 4 pins, but they are floating around 1 kHz on the frequency meter at the amp end so I think I'm probably getting a signal from the H/U. The other connector at the amp is an 18 pin plug. 2 are 12v, 2 are gound, 2 are unused, and the other 12 are speaker wires. 8 of the wire colors match the wiring diagram I found on this site for the front, and rear speakers although I didn't trace them to the speakers. The other 4 wires match the wire colors going into the tweeters. (I did trace those because the tweeter covers were easy to pop off and I wanted to be sure.) Both front and both rear speakers seem to still have good wiring. There is continuity from + to - and the resistance checks out at about 3.4 ohms. But I couldn't get a resistance reading across the tweeters. I checked continuity on the 4 wires individually from the amp connector to the tweeter plug in the door and they are still intact, but I can't get continuity or a resistance reading across the tweeters themselves. Maybe they are so small that my cheap-o multimeter can't meausure it, I don't know much about tweeters. Any ideas on what else I should check? I've tried everything that I can think, maybe it's time to call in a pro. My best guess is that the amp has died. Is this a common problem? My wife is the primary driver of this car and doesn't usually crank the volume up too loud. Also, I thought there was a 7th speaker in the center of the dash, but there's no additional wires coming from the amp. Could it be driven directly from the H/U, or am I just totally confused? If there is a center speaker driven directly from the H/U, then does it still make sense that the problem would be with the amp if that speaker isn't working either. Thanks for any advice you all can offer. I apologize if this post is too long, but I figured I should include as much information as possible.

I actually like doing these cars. Easiest amp re-wire car, especially since you can pull the amp harness all the way up to the radio cavity with no problem and use a daewoo harness to still give it a clean look.

Thanks for the comments. I called the Mitsubishi dealer this morning and the list price is $747.75 for a stock replacement. I laughed out loud and the guy said "Yeah, Infinity is pretty proud of their stuff." I think it's safe to say I could get a lot more for a lot less money with an aftermarket replacement. But we were satisfied with the original system and it would be a whole lot easier to just plug in an original replacement. Does anybody know where I could find a used one for sale? The part number is MR400692. Thanks again.It aint broke, that's a design feature!

Good news! I had come to the conclusion that the amp was dead, but then it started cutting in and out this morning on the way to work. So I took it into the office and one of my co-workers, who happens to be an electrical engineer, offered to take a look at it. We cracked it open again and he grabbed a solder gun, re-touched all of the solder joints where the power and ground wire terminals connect to the printed circuit board, and now it works. $1.99 for a tube of heat sink paste from Radio-Shack to keep the power circuits in contact with the case and it appears to be as good as new. Maybe this will help someone else someday. Just be careful if trying this at home kids! Those little capacitors can hold a charge for a long time. 5 hours after I unplugged it and they still make a nasty little spark if you touch the wrong terminals at the same time. I'm just glad I didn't fry it for real.It aint broke, that's a design feature!