I have a stock radio/cassette player with the optional 6 disc cd player. It's worked fine for a couple of years but last week while I was listening I saw smoke coming from the front, left door speaker and then a loud POP! Got home, took off the door panel and saw the crossover and wires had gotten so hot they exploded and splattered solder all over the speaker grill. I thought the speaker was just old cuz the other 3 still worked fine. Got a replacement from a yard and worked fine till a week later and it did the same thing. One strange thing, once in a great while, when I first turn it on all the speakers would make a super loud thumping noise. I'd turn it off and then back on and the sound was gone. My first thought was something was grounding? But checked all wires coming from the separate amp to the speakers and nothing was grounded. Turned on the radio and all positive and negative wires had completed circuits(continuity). What surprised me is when the radio was on all those circuits were complete but also grounded to the chassis. That puzzles me? How could they work grounded? I thought the amp had burned out and that's what grounded them. But, again the other 3 speakers all work fine(while grounded) and I hooked a small, spare tweeter to the wires that had blown and it works fine too. Could the amp have overheated and caused the speaker to blow? If it was the signal from the radio I would think it would affect all left side speakers. Any thoughts? Thanks

 

I'd think that its possible for the amp to push DC which would in turn fry the speaker. Another fault could be a frayed wire which touches some other DC source. More likely it points to a fault in the output stage in the amp

 

What do you mean by "push dc"? I thought everything in the car ran on dc.

 

Speakers don't. Audio signals are AC of varying frequency. Pushing a DC current will ruin most speakers.

My bet is there is a frayed wire where the wires run into the door causing DC to cross over into the speaker wire. Last time I examined wires going to the doors of our '89 240, all had cracked insulation where the wires flexed.

 

OK, I looked up AC to DC "Clipping" and I get it now. But, are amps permanently damaged when they "Clip"? Mine seems to work fine after it blew the speakers. Or so I thought. Just hooked up a spare speaker and turned it on and both front speakers we're thumping loudly and I could see the cone moving a huge amount back and forth. Slid the fader to play just the rear speakers and no thumping. Slid it towards the front and the front we're fine with no thumping. Since both, left and right we're thumping I'm pretty sure it's not a frayed wire(even though I did have that problem with my mirrors a while back). And, again, here's a strange thing - when the thumping stopped and all 4 speakers we're working fine I checked for continuity between the speaker positive lead and the chassis - and it was connected. That's what I don't understand - how speakers can be grounded to the chassis and still work? Anyways, I think it's the amp. But the fact that the front to rear fader(on the radio) seemed to eliminate the thumping could it be the radio signal going into the amp?

 

UPDATE: I'm pretty sure it's not the fader in the radio. I have a spare radio, swapped it and same results - when I fade to the rear no problems, when I fade to the front popping, thumping and screeching(in both left and right). It's got to be the amp.

 

you're dealing with 25-30 year old electronics in a hostile environment. its amazing the factory audio works at all.

 

That's why Volvo's will be around when the world ends.

 

But not the oe radio...

 

Ha! It would if it was a Swedish radio. Damn Alpine(not Swedish)!

 

for what its worth, these 'swedish' volvos are very international. the AW7x transmissions are Japanese (Aisin Warner == Toyota), the HVAC system is part American (GM), the engine electronics are German (Bosch), the rear axle is a Dana 30 (unclear if Volvo manufactures it under license, or buys them from Dana), etc etc....

 

Oh I'm aware of that. I heard a long time ago that Volvos we're the red-headed stepchild of the automotive industry, with all their mix of parts.

Problem update: now I think it's the radio again. The dash speakers stopped working sometime during the last 2 days with all the thumping going on. I tested the speakers and they work. But there's no signal going to them. And, if I'm correct, that comes directly from the radio and does not go through the amp. I wanted to keep everything original but I guess I'm going to have to get an aftermarket radio. Does anyone know of a brand that will allow the 6 disc/changer to plug in and still be used?

 

so what year 940 is this? I have wiring diagrams for most of them.

 

It's a '93 Turbo Wagon and I was able to print the wiring off the Mitchell site, thanks.
http://www.v8volvo.se/mekartips/volv...%20Michell.pdf
The problem is, those charts just show speaker and power wiring. I believe my problem is internal, inside the Alpine CR-814. I searched for schematics and couldn't find any since it's not made anymore. I did find out that if I go aftermarket I'll lose use of my 6 disc CD changer. No one makes any kind of adapter. What's really weird is all the speaker wires going to and coming out of the auxillary amp are complete and not grounded. The dash tweeters come directly from the radio's amp and each have 2 leads - pos and neg. So it's not a common ground setup. Yet, both neg leads(right and left) show continuity(grounding) to the radio chassis. Which is why when it's powered on and I slide the fader to the front speakers I get an incredibly loud screech coming from them. And when I checked another similar radio I had as a backup, it showed grounding with the neg leads also. What are the chances that 2 radios would have the identical problem? Or am I missing something and they were designed that way - with a common ground? But why have a separate neg lead for each side if it's common ground. Has me up a tree right now.