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Yellow Fever Answered

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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)2008-07-02

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.

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gmoon (author)Punkguyta2008-07-02

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

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Punkguyta (author)gmoon2008-07-02

>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.

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NachoMahma (author)Punkguyta2008-07-02

> 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.

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Punkguyta (author)NachoMahma2008-07-03

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.

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Big Bwana (author)Punkguyta2008-07-03

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....

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Punkguyta (author)Big Bwana2008-07-05

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.

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Big Bwana (author)Punkguyta2008-07-05

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 ))

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Punkguyta (author)Big Bwana2008-07-07

OOO ANTIMATTER IR EMITTERS? I must buy up all their stock!

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NachoMahma (author)Punkguyta2008-07-03

. I could only find user manuals on the Mirage site and no schematics show up on Google. :(

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Punkguyta (author)NachoMahma2008-07-03

Damn..Well I appreciate it non-the-less. The mirage can go sit on my shelf and percolate for a few months. I got my sony surround sound amp driving my sub right now through the right channel, I'm in the midst of hunting down a free 0.36uF or 400nF capacitor so I can make an inline crossover for it. I actually like the hard bass with authority this sony has, let's just hope I don't blow this one or I will be crying >_

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Big Bwana (author)gmoon2008-07-03

The mirage amp, if it's like most smaller sub amps is more then likely a Class D, so it's just a glorified switched mode motor controller, this is common in sub amps because unless they are very well designed, they tend to suck when amplifying higher then bass frequencies... But they are cheap to build and don't need large heat sinks... But like you said the two heat sinks are more then likely opposing polarity and it more then likely killed some section of the power supply, or it might of just taken out a PCB trace (( some times this is overlooked )) and consumer electronics have also started to use fuses that look like other electronic components like resistors (( Commonly drab green color with black writing and about the size if a 1/2 watt resistor)) and Capacitors (( These are black bottomed with a clear plastic top and they are about the size if half a tic-tac ))

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gmoon (author)Big Bwana2008-07-04

That may well be BB, I was just guessing ;-)

I figured the manufacturers were still bragging about Class D (like you said, PWM) audio eq, and Punkguyta would have mentioned it. Isn't the Pioneer the sub amp?

You can certainly find examples of push-pull with a IRF640 and it's P-channel complement, by Googling for IRF640, mosfet and amp.

It's also occurred to me since that if the mosfets are identically marked, they probably aren't N and P, but both the same. That doesn't prove it's not Class B--they could invert the phase for one elsewhere, especially if there are discrete chips for that stuff now. But it makes it less likely that it's Class B....

If it's Class D, it's very unlikely that the heatsinks would ever develop a differential voltage, tho. I can't really understand why the sinks would ever be anything but GND, anyway, since it's common to bolt them to the PCB instead of using a sink--unless they've got the all-black package....

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Big Bwana (author)gmoon2008-07-04

gmoon All the smaller sub amps I have seen are class D so I might also be only guessing I haven't seen that many.. And a manufacture bragging about them, I don't know why they would other then the fact they are cheap to make and they can make huge sub amps, in the 1500 watt range for under $250, and I have seen a 750 watt one, transformerless, line powered using a SCR and a few caps to get your positive and negative potentials, and I could build it at home for under $100... But if your trying to put any thing above 500 Hz into it, you'll quickly realize just how horrible it sounds, but it only weighted a few pounds.... (( well unless you have the money to buy a Bang and olfsen, spelling might be wrong ?? I have heard a nice one from them, but there swithcing frequency is way up there with there dollar figure.. )) And his FETs are not Isolated packages so the heatsinks where more then likely at input potential, if they where both on the same heat sink I'd say they would of used insulators but on two heatsinks, who knows a good ceramic insulator for a TO-220 can be worth more then the $1 the IRF-640 is worth..... And he might be better off to just build a new Amp and use keep it simple and used some thing like a NSC LM3886, 68 watt amp and two of them bridged will output in the +200 watt area with out much effort and if his transformer and caps and diode bridge is OK he's more then half way there....That and they are very, very self protecting and all the ones I've played with take lots of abuse (( I don't like the Spike shutdown / way it clips, but it is a good idea )) Punkguyta, a cleaner photo would be nice of the main board looking straight down ...

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Punkguyta (author)Big Bwana2008-07-05

Under $100 you say?!?!?? How might I build said amplifier....? I don't really want to ever put anything over even 200hz at the very most. My sub isn't made to radiate high freq. sounds from the front, or any at all, the rated cutoff is 23.2hz for it's absolute low, which is pretty wack. However you'd need a big box to match that, which I don't have atm. Do they actually have protection built in? Like is it a hard shutdown or is it a built in cuircuit. 68watts seems a little low, even 200, the sub says 1200 watts rms, I know that's still not absolute true wattage, but still, at least 600-800. Would you be able to help me get together a list of parts so I can go to the store and see what they can't order me. PM me mate.

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Big Bwana (author)Punkguyta2008-07-05

Punkguyta : Ok since you have it all taken apart, flip the board over and make sure nothing is going to short out against the case of other things, use a sheet of paper / cardboard to make sure if there’s any conductive surfaces around, You will be powering it up…. Once every thing is safe, power the unit up with no Signal being input, and no Speakers connected, nothing should over heat when it’s like this … Now measure the voltage across the capacitors they should be in the + / - 30 to + / - 60 volt area, this tells me the bulk of the power supply is working, the transformer, Diode Bridge, and capacitors… (( The most expensive parts if your going to build a new one ((( Ok a simple LM series amp ))) Now 68 Watts may sound like nothing, but this amp will deliver 68 watts RMS, that’s what 6,800 watts in car audio lulla land, and it will rival most under $700, big brand name amps like Sony, JVC, Pioneer, etc… And with a simple mod you can bridge two chips together and you effectively double the voltage and current so you get 4 times the power, but it doesn't work that well due to heating issues but you can get about 200 watts into 4 Ohm speaker with MAX voltage input….. What type of speaker are you driving, because this should drive most Car Audio speakers, and may even damge some (( Car audio specs are normally a pyle of lies )) It will also drive most home audio speakers, and for a basic sub application it would not be hard to add to the power output stage if you need a lot more power….. Now you asked about the protection A LM3886 amp IC has, it has a rail fault shutdown, Overtemp Shut down, Die temp shutdown (( spiKe trade name, this is the annoying one because it sounds like clipping because it shuts down and turns on so fast, but the tradeoff is, it protects the amp very very well )) And just for you they built in Short Circuit protection…. So when you let us know what voltage your playing with, and the input specs on the AMP, and what speaker your driving I’ll let you know one of the cheapest ways to build a good quality amp… Also you asked about Arctic Silver (( It’s over priced )) it will work (( but no better then the white stuff)) And Aren’t they nice when they squeeze hordes of it all over the place…

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gmoon (author)Big Bwana2008-07-04

Yeah, but I think the Pioneer is the sub amp, and the Mirage isn't. But I'm not sure PunkG said if the Mirage was a sub driver or not. I dunno--it's not SMD, so it wasn't made recently (10 or 15 yrs.) Again, hard to draw any conclusions from the info we've got... I believe there are some full-range Class D amps today, and that you'll see more and more. For those you pay, or did pay, a premium. Although searching for Mirage, I just get RF amps (???).

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Punkguyta (author)gmoon2008-07-05

No the mirage was my main sub amp. (I still can't understand how you guys got it mixzled) When I blew my mirage amp while it was running, I freaked out and pulled the pioneer out of a small theater sub I had just to hook it up and make sure the sub wasn't doing some rat rat rattleing. It's 2004 built, and has some simple ic circuits, it has auto shutoff, all the goodies. But still a simple cheap amp, and it worked good for what I need it for.

And mirage as far as I know didn't make rf amps. Would this be the proper link maybe?

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Punkguyta (author)gmoon2008-07-05

I didn't really like this amp no, but it was more proper than hooking it straight up to the right channel on my sony surround sound, that just isn't good to run it like that. Plus I don't have any inline rca cutoff filters so the sub gets the full signal, just not very effient. Oh and no the pioneer I pulled out of a small home theatoer sub I wasn't using just to make sure my sub was still okay, and I just ended up having too much fun and blowing it. The transistors were bolted straight on with no isolator (why exactly would you want voltage going through the heatsinks anyways?). The car amp I had

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Punkguyta (author)Big Bwana2008-07-05

But I looked at the entire pcb, pulled the whole amp right apart and I don't see any burnt markings, and I have seen browned pcb's before so I know what to look for. Nothing funny looking, the two power cap's (4700uF 63V) appear to be fine, no leaks or bulging. Just look at the pictures above for the amp, I know they're a little blurry, but that's all I got. Oh here's a question I just noticed something, what appears to be a 473J SS resistor although I can't find a datasheet on it. Do they normally have a small bulge to them? Like it doesn't look scalded or cracked or anything.

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Punkguyta (author)gmoon2008-07-05

I have been looking for a couple replacement mosfets online in samples or even some I could buy. Do I have to buy separate N or P mosfet transistors or is that just negative/positive and they work either way?

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Sandisk1duo (author)Sandisk1duo2008-07-05

did you even see this comment???

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Punkguyta (author)Sandisk1duo2008-07-05

nope not till now, thanks mate.

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Sandisk1duo (author)Punkguyta2008-07-05

hope you get your amp fixed!

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LinuxH4x0r (author)2008-07-02

Wow, haven't seen you for a while. Where were you?

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Punkguyta (author)LinuxH4x0r2008-07-02

I was fed up with the flakyness of instructable's interface, which is still acting up in safari, gah. And to boot, no one wants to help me, I've fried 2 amps now. 2 FRIGGIN AMPS!!! I need someone to tell me at the least where I can find a semiconductor company that will sell me some mosfets for my amp(s), they aren't that expensive so maybe they'll even send me some free 'samples'.

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LinuxH4x0r (author)Punkguyta2008-07-02

Go for the free samples. I've had good luck with fairchild, analog devices, and TI (molex for connectors)

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Punkguyta (author)LinuxH4x0r2008-07-02

I just emailed Vishay to see about a free sample request on IRF640 mosfets, they offer samples for other mosfets, just not the one I'm after. I wonder, do you think I could replace it with a higher capacity transistor to achieve higher wattage output from my amp?

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LinuxH4x0r (author)Punkguyta2008-07-02

Go for it! You could also try some other suppliers. Do you know of any that will give sample solar panels

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Big Bwana (author)LinuxH4x0r2008-07-03

Wishing you all the best on sample solar panels, maybe panasonic but they will be the size of calculator panels ((Few mW areas (( but they have huge efficiencies ))

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LinuxH4x0r (author)Big Bwana2008-07-03

I'll try. Maybe I can pass it off as for a cell phone charger :)

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Big Bwana (author)LinuxH4x0r2008-07-03

If you only need a couple of watts why not look at walmart they where knocking off 15 watt panels for $85 and 2.2 watt panels for $10.... ((( And Panasonic uses a rep company, varies by area, but they came and visited me, but the rep was pretty cool and insisted I need all sorts of things I didn't even ask for, I'm guess if they look busy this is how they get paid )))

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LinuxH4x0r (author)Big Bwana2008-07-03

2.2 for 10 isn't bad. I just don't feel like forking over $180 for 45w

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Punkguyta (author)LinuxH4x0r2008-07-05

That's actually pretty good when you figure that up here, I had an electrician tell me around $1500-2000 for a 180 watt panel (and that's at peak conditions), and that alone is just barely enough to run a 6 foot florescent light. (40W a bulb)

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LinuxH4x0r (author)Punkguyta2008-07-05

Still, I should wait for process to go down

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Punkguyta (author)LinuxH4x0r2008-07-02

I just signed up for an account on Fairchild, clicked the sample button on my part, and it says denied WTF. And no, I doubt that anyone is willing to give solar panels away, they're still rather dear. And if I recall, we still haven't even hit 60% efficiency, they're actually pretty much a waste of money right now.

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LinuxH4x0r (author)Punkguyta2008-07-02

Maybe its too expensive. Who cares how bad they are if they are free!

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Big Bwana (author)LinuxH4x0r2008-07-03

Or a high demand sample, and it is a low cost part, so they normally expect you to buy them, they will however sample through a rep but once again that's more work then it is to buy them, unless your a serious designer who deals with the reps all the time....

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Punkguyta (author)LinuxH4x0r2008-07-02

I don't even think it breached the $2 mark. And on the other side, it'd prolly be cool to collect numerous solar panels from many manufactures as free samples and then be able to power your house from free solar panels. I could see the novelty in that.

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LinuxH4x0r (author)Punkguyta2008-07-02

yeah, that would be awesome! (thats what I want to do, but only for my room)

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Punkguyta (author)LinuxH4x0r2008-07-03

Well if it's for your room, you probably wouldn't need that many panels, just make sure you can get your hands on some kind of rechargeable battery bank, the more the better, that way you can keep a longer buffer charge (think 1-2 days backup charge for 2-4 lights or maybe a TV).

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LinuxH4x0r (author)Punkguyta2008-07-03

I need at least 20 watts. 10 hours of sunshine to charge a battery to power my 200w inverter for an hour. 40 would be even better. I already have one of those car jump starter pack. Its great for having a portable outlet in the middle of nowhere

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Big Bwana (author)Punkguyta2008-07-03

International Rectifier offers samples of fets but you have to put in so much work to get them your better off just buying them... And I'm talking hours on the phone finding who to ask in your area, meeting them in some cases (( I meet them )) and then they send the samples to a store near you in about two weeks, and you have to go get them, and hope they don't bill you for them (( Ok the guy in the store by me was questionable ))

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Lftndbt (author)2008-07-02

Take the word starting with c that shouldn't be there out. Can I ask what the original issue was, that caused you to search for a reading?

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Punkguyta (author)Lftndbt2008-07-03

Take what word out what what? >Can I ask what the original issue was, that caused you to search for a reading? . The original issue was that I had ONE blown amp, which nacho has pretty much confirmed that it's a final output stage blown. So most likely the N and P channel mosfets are blown, even though they look fine, I'm waiting on a reply from Vishay electronics on any word of a free sample order. Wowa is me, wowa is me, I have the skills thankfully with a soldering gun to replace said parts, now it's just a matter of getting my hands on a pair or even something higher capacity so I can have a higher power amp.

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PKM (author)Punkguyta2008-07-03

Presumably Lftndbt takes exception to your use of the word "crap". I don't see anything else there offensive starting with "c".

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Punkguyta (author)PKM2008-07-03

hmm, Oh woe is me, oh how worrisome some get from words. What's that my kindergarten teacher taught me? "Sticks and stoned may break my bones, but bad words and cold prickly's may not"

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NachoMahma (author)Punkguyta2008-07-03

. Several ppl who are trying to help you get out the mess that you got yourself into have made it clear that they do not like some of the language you are using. Pull your head out of your butt and try to act like a decent human being. Or at least fake it long enough to get what you want.

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Punkguyta (author)NachoMahma2008-07-05

Nacho.. I sincerely apologize if I did actually burn some virgin ears. I even will go far enough to apologize for trying to be different from the rest of the world. We all try to hard to fit in with one another, and honestly I can say at this part of our evolutionary stage, individualism really plays a main role in development towards a society we're aiming towards, which is in a rather big jumble, yes individualism is still there, but people rely on others to embrace their culture or else they try to fit in somewhere else. Enough of the shenanigans I declare and let that sit in your cranium for a short whisper of a time. -Punkguyta, Sincerly yours.

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