Prosonic PQR 9850 Lights up but no sound..

[RaleighRon]

I picked this a while back and it was totally dead. Pulled it apart found the fuse blown. Put in a new fuse blew again and I tossed it on back burner a bit.

Took another look last night and found the power wires reversed to the board. I flipped those and a new fuse it's lights up as if it's working but now SOUND. Nothing! Tested with head phones and no sound. Tried the mic jacks and nothing.

Any help where to check next? I'm not sure how to test the amps or anything. Was hoping for some videos on you tube but don't see much. Any help is appreciated.

 

[floyd]

My wild guess would be that if the wires got crossed it probably blew out the amp ic chip/chips.

 

[RaleighRon]

My wild guess would be that if the wires got crossed it probably blew out the amp ic chip/chips.

I think I see 3 amp chips on this 1 including the pre-amp. Think if I located replacement versions and replaced them that would get me back in business?

 

[Superduper]

Amps might have blown, but I think it's equally likely, perhaps moreso is that the regulators might have blown. Every circuit includes regulators to protect voltage sensitive circuits, and these regulators are probably more susceptible to damage than the amp chips themselves.

 

[caution]

Amp chips often run on unregulated power - if that's your case you may have issues with both the amp chips and the regulator circuits

 

[Ghettoman]

i have a friend that connected power to the DC socket on his 777, little did he know that a lot of boomboxes run on Negative centre on the DC in Socket. so when he plugged it in, it blown both Amp IC's, i replaced them for him a few months ago, and it's been fine since, so i'm guessing that's what happened to yours. that's the first thing i'd change.

 

[floyd]

Amp chips often run on unregulated power - if that's your case you may have issues with both the amp chips and the regulator circuits

This is true with car amplifier . in almost every case if the amplifier chips are burnt out the regulator circuits are toast too. It's usually a 3 or 4 leg transistor that regulate the power to the amp ic. Mind you I'm no genius but it's a learning experience for me as well.

 

[RaleighRon]

Replaced all the Amp chips expept the pre amp. Still no sound but when I plug in headphones I can just barely hear the radio. I'll look into the regulators next I guess.

 

[Ken]

Replaced all the Amp chips expept the pre amp. Still no sound but when I plug in headphones I can just barely hear the radio. I'll look into the regulators next I guess.

These are surprisingly great sounding boxes, but fragile electronics. Replace the pre amp. Replace everything connected to the supply side and the output side of the amplification section, all this abuse did was strain every component into being one step from failure. Field strip the board and replace everything, or you just may be coming back again. Personally, I like confidence when I spin that dial up to 11.