Phoenix Gold Phorum

Hi again good folk

Been a while since I've been on here, but now that I'm in need of some advice i'm back.

BTW - I tried to search for some of the answers, but I couldn't get the search narrowed down to any usable degree, so sorry if this has been answered anywhere else.

I was going to a comp the other day and driving with the music on pretty loud and on the way my tweeters shut off suddenly, it's powered by a Route66, the mids are temporarily powered off another amp with more power. There were nothing audibly wrong at any point - The higher frequencies just stopped. I pulled over along the road and took a look at the amp, the amp switched on with the remote from cd, m44 turns on like normal, led indicates red and switches to green, but no sound(front output power the tweeters) - m25(not in use) indicates red and shuts off again immediately, took a little sniff and smelled burned electronics - Disconnected the power.

When I came home I pulled it out and opened it, upon visible inspection I noticed something bad - The transistor on the right of the heatsink on the M25 was missing a piece(!) Didn't notice anything else wrong, but I will do a closer inspection when I pull out the board.

What could have caused this? What should i check for? (No visible electrolyte btw)

There are no outside factors(I mean shorts, low voltage, etc) that did this besides heavy vibration? The amp is mounted in a rack in a sealed area with nothing loose in it and I have a serious power supply with very good/perfect connections, so nothing wrong there. But I'm a SPL competitor, so 148dB@36Hz is pretty daily, which causes "some" movement in everything, could the vibrations make this single transistor explode like this?


When I have the amp on the operating table anyway, I would like to exchange the caps and anything else that needs replacement after these years of service. I need to buy the parts before I pull apart the amp since I can't have it laying around with kids/animals around. Could anyone please make a list of article# needed or point me to a post that contains this(Like I stated earlier I couldn't find anything when searching)?

I need a parts list for M44 and M25.

I also need the part# of the transistor that blew in the M25 since it exploded i can't even find the parts to puzzle it back together. It's the one located on the far right of the heatsink.

Hope somebody can help with this, it is much appreciated.

That can happen when a speaker shorts out. It could have shorted to the metal (ground) of the car for a split second, enough to self destruct that transistor. You should check your wiring, especially areas where it runs through any holes in sheet metal. Something may be partially cut somewhere.

Sorry for not pointing it out better, but the m25 part of the amp is not connected to anything, it just has power so that i can use the m44(front). This (the m44) part of the amp seems to be working except no output, but as i understand it, this is normal when the other half is not powered on?

are you sure it is the output of the amp? Have you tried swapping rca's to se what happens?

I didn't try to swap rca's as this is close to impossible to do without pulling out all the wiring, but I measured the rca's to be sure and there was an ac signal in.

Can you post picture damaged area?

I don't have a camera at the moment, so it would only be one from the SHITTY cam on my phone..? If it helps the red circle here is the blown transistor:

Sorry about the shitty quality, but it's the best I can do atm.

The M25 power supply MOSFET's blow up. Did you try if the M44 side worked? You said the M25 side was never connected. It good chance if you replace MOSFET's and 100 ohm gate resistors amplifier will work again but you also need check Output XSTR's, rectifier diodes for rail and stock supply.

Are the two MOSFET's in tha last picture the same? I need to order a new one and the specs are blown away.

The M44 side seemed to work properly, but no output. It powers on like normal and doesn't go into protection.

I know how to solder and a little about components, but i'm not that knowledgeable about technical terms(especially in english), so I have to ask, where are the "Output XSTR's, rectifier diodes for rail and stock supply" located and how do I test them?

I have an O scope and a couple of different meters of good quality available.

Thanks for the help btw

Update: Got some time to look at the amp today, so i pulled it apart and got a nasty surprise. Seems part of the board is charcoal.

that could be the problem.

i figured it was a cap with the size of the black spot on the case.

hmmmm...

Looks like you got to put this amp in a "norgespakke" and ship it over to me ..... & I`ll pay you some small $$$ for it....
You just got to let this one go ....

Good thing is you can drop in an M25 board and it will at least be functionally fine!

ttocs wrote:that could be the problem.

i figured it was a cap with the size of the black spot on the case.

Looks like it is the two resistors in the middle of the black that burned, unless there were something else under there that is gone now.

holmis wrote:hmmmm...

Looks like you got to put this amp in a "norgespakke" and ship it over to me ..... & I`ll pay you some small $$$ for it....
You just got to let this one go ....

No way dude..

stipud wrote:Good thing is you can drop in an M25 board and it will at least be functionally fine!

That is good news. "Just" have to get one and then figure out what needs to be removed from the "new" m25 board to make it fit and work. I will eventually repair this board though, this amp is very special to me

Any idea if it is possible to do something so that I can use the m44 part of the amp while I try to find a m25? The m44 part won't give any output without the m25 as it stands now.

it is hard to tell if there is enough left on that board to salvage. Clean the black off and see how much of the traces it left. It might be a parts amp now...

That doesn't really matter. I'll make an insert for the burned board if need be. I have a friend with access to the equipment to etch it.

Still need another m25 as a guide for the traces and what components are missing though.