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Yellow Fever

I'm peturbed, even that more at the quick flagging response, yet no help to my situation, regardless I'll ignore that. My mirage panel amp uses IRF640 mosfet transistors, and I did something to it in the process of trying to take an amperage reading with my multimeter between the two energized heatsinks (theres two mosfets for a mono output), after the big FLASH BANG, I pulled it apart after ripping the cord out of the wall. The only damage I can find is a small black pit that the spark made in the metal heatsink (actually it was pretty deep for a spark pit). I've checked the mosfet transistors, included cleaning the MASSIVE amount of ceramic thermal paste they smeared on there with some rubbing alch to get a nice clean surface on the heat sink and transistor. By the way, would arctic silver be a good substitute for the crap paste they put on there? They're designed to make contact with the heatsink anyways so I don't see why silver thermal paste would hurt it. But besides all that, I can't find any brown spots on the PCB or any bulging capacitors (there's only two main power caps), did I perhaps just flip some kind of internal circuit breaker built into the circuit as a whole, not just as a single device I can see? I'm wondering if I should just chuck it instead of putting it back together and plugging it back in to be greeted with another spark, although it didn't smoke or anything while it was plugged in after the spark, but I got a quiet humming sound on the sub and the music stopped coming through. Again, maybe I blew some kind of breaker? Oh and I know it's my fault guys, so don't be rubbing that in my face, I come here only for help and not to be a nuisance.

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Punkguyta (author) 8 years ago
Well I think I just blew my pioneer amp, I was testing the sub which I think is "marginally" okay, and I liked how much power this other amp had so I cranked it. And that ended with a pop and no music..damn. Might have been that the amp was designed to drive a 26 ohm sub not my 8ohm DVC.
gmoon Punkguyta8 years ago
Two amps shot...ouch.

You likely shorted something on the mirage...It sounds like a Class B amp push-pull amp, so each transistor (a N-channel and a P-channel) was handling opposing peaks --maybe the heatsinks were opposite polarity. That could take out a bunch of different components, everything from the power regulator to the power transistors themselves...sorry, dude.

For the other amp--8 ohms is a much larger load than 26 ohms (less resistance = more current = greater load.) Solid state amps just can't take something that far out of spec. :P
Punkguyta (author)  gmoon8 years ago
>You likely shorted something on the mirage...It sounds like a Class B amp push-pull amp, so each transistor (a N-channel and a P-channel) was handling opposing peaks --maybe the heatsinks were opposite polarity. That could take out a bunch of different components, everything from the power regulator to the power transistors themselves...sorry, dude.

. .............*flinches* Well..

Like I said, nothing 'looks' fried other than the black spot my test lead left on the heatsink. I requested two mosfets (the ones that you discribed, the N and P ones) from Vishay (see my above post to Linuxhaxor).

But now that you mention it, what's the difference between the N and P channel? Just reversed polarity? Or will I need to get a different transistors? These ones also have what appears to be small resistors or a temp probe glued to the top of each transistor, will it matter to have these connected to operate it?

>For the other amp--8 ohms is a much larger load than 26 ohms (less resistance = more current = greater load.) Solid state amps just can't take something that far out of spec. :P

. I kinda figured that as I did noticed before I even hooked it up, but It was eating me up inside thinking that I just had 120V go through my sub (I figured thats what the big spark on the mirage did) so the pioneer was the only other amplifier I had to try, which was still all together with it's own subwoofer. Now I kinda wish I had of left it alone as it was a good little sub, but it was given to me free so I can't really cry about it. My pyle I can as that would be a loss of $150 and I'd be left with a rathe large and heavy paperweight that moved up and down.

However, thanks for the input gmoon, helpful as always.
> These ones also have what appears to be small resistors or a temp probe glued to the top of each transistor . That may be your problem. Could be fuses (current or thermal). Maybe not. . , will it matter to have these connected to operate it? . If they are fuses, yes.
Punkguyta (author)  NachoMahma8 years ago
Actually Nacho, I was looking at them closer, and they look more like diodes, really small ones with a dark clear orange casing, definatly looks like a tiny diode like something similar I've seen before, although I still can't figure out the function of it. And no, I can't find any schematics, but if you're up for a search while I'm in the hospital today (I'll explain later), look around for something relating to Mirage Nano Sub Panel Amp Part no. 6XEE153ZZZZZ or LR77905 Those are the only two number I can find on the actual panel that related to the amp as a whole. Thanks Nacho.
It's not uncommon to use a diode as cheap temp sensor, I've even seen a LED being used as one, Accuracy is less then desirable but if you don't mind it being out 15 degs, they are cheap....
Punkguyta (author)  Big Bwana8 years ago
So what does this mean? That maybe it's still okay? I never did re-assemble it and plug it back in, I'm a bit afraid of it doing the smoke of death thing.
Smoke of death ?? no no it's called magic smoke, and it's stored very carefully by the factory, and they pack it into every chip, every transistor and every diode they make... the magic is keeping it in... (( Anyone want to buy some new darkness emitting diodes I just got them last night and the darkness was amazing ))
Punkguyta (author)  Big Bwana8 years ago
OOO ANTIMATTER IR EMITTERS? I must buy up all their stock!
. I could only find user manuals on the Mirage site and no schematics show up on Google. :(
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