Phoenix Gold Phorum

Hey all!

It's been a long time since i came here! I had little to no free time theses past months, new job in a garage shop taking lots of my time...

Today i found a Xenon 1200.1 amp in one of the cars we were about to trash. Amp looked in nice shape, but when i hooked it up it wouldn't power, keep blowing fuses. If something i learned the hard way, i did not try to put a bigger fuse and simply brought it home. I just opened it, and found out that one mosfet is missing. I'm planning on repairing this amp, and probably use it with thoses RSD12 that i have boxed since my last install...

Here are some pictures of the beast :














The board seems okay, but is covered with a small film of dirt, as if the amp was in a smoking environnement for a long time. There's no burn smell, and the caps seems okay. Should i change them anyway? Also, i remember reading that it's better to change all mosfet when you change one, should i do that?

Thanks for your helps guys! By the way, i like the new phorum design!

You don't need to change caps (I am pretty sure). If you replace the missing MOSFET, you need to replace all those like it.

I will warn you though, I have a stubborn X600.1 I cannot repair. I put new MOSFETs in it, and replaced all the gate resistors (which you should do as well), powered it up and the amp worked fine. Gave it back to the owner, who installed it, and then it went up in flames. All the power supply MOSFETs failed. So I replaced them again. And new gate resistors. And I found one bad cap (tiny mylar style) in the signal chain which I replaced. Powered it on and it worked fine on my test bench. I then set it aside for a month or two on the shelf. I got ready to sell it so I hooked it up again on the test bench and all the MOSFETs went up in flames one more time. I have no idea what is causing this, or what is even going on. I did not even have any speakers connected to the amp when it failed the last time. Simply powering it on caused it to fail.

Maybe the PWM controller is to blame. I looked at its output on the o-scope and it is good, so I am still lost.

Thanks Eric!

So i should be replacing all the FQP65N06 only?

Do i only put thermal paste or is there something else i must apply? I know some amps have something between the mosfet and the thermal paste, but can't remember the name...

welcome back str3atwarrior! where you been? how's the new car? did you install any gear in the new car since the fire?

money-b wrote:welcome back str3atwarrior! where you been? how's the new car? did you install any gear in the new car since the fire?

Hey how ya doing? I changed car again, i now have a hyundai accent 2000, with my old deck, a QX2180 amp and one XS124 sub, nothing big but still working great!

cool.....good luck with your repair.

I think you would be fine with just the thermal pad which is there. Remove all the MOSFETs for the power supply, and the gate resistors. Hook the amp up to power and check the output of the PWM controller for a good PWM signal. (I would start by measuring where the gate resistors were).

On my X600.1 there is a pair of transistors between the PWM and the gates, and these had failed as well. Once replaced my PWM controller started producing a good signal.

Just ordered 12 new mosfet, will let you know!

Nice score, gotta love findin' PG Goodies.

hey eric, maybe you need to use some parts off of zpa .5- that would probably fix it....

davewaibel wrote:hey eric, maybe you need to use some parts off of zpa .5- that would probably fix it....

You could be right, maybe a little magic is just what my X600.1 needs...

be settin speakers on fire fo sho then!

dvnt88 wrote:Nice score, gotta love findin' PG Goodies.

Yep, and it kills me to think that if i would not been the stripper for this car this beauty would have finished in a scrapyard

Eric D wrote: I will warn you though, I have a stubborn X600.1 I cannot repair. I put new MOSFETs in it, and replaced all the gate resistors (which you should do as well), powered it up and the amp worked fine. Gave it back to the owner, who installed it, and then it went up in flames. All the power supply MOSFETs failed. So I replaced them again. And new gate resistors. And I found one bad cap (tiny mylar style) in the signal chain which I replaced. Powered it on and it worked fine on my test bench. I then set it aside for a month or two on the shelf. I got ready to sell it so I hooked it up again on the test bench and all the MOSFETs went up in flames one more time. I have no idea what is causing this, or what is even going on. I did not even have any speakers connected to the amp when it failed the last time. Simply powering it on caused it to fail.

Maybe the PWM controller is to blame. I looked at its output on the o-scope and it is good, so I am still lost.

Your problem is transformer.

valeks1 wrote:

Eric D wrote: I will warn you though, I have a stubborn X600.1 I cannot repair. I put new MOSFETs in it, and replaced all the gate resistors (which you should do as well), powered it up and the amp worked fine. Gave it back to the owner, who installed it, and then it went up in flames. All the power supply MOSFETs failed. So I replaced them again. And new gate resistors. And I found one bad cap (tiny mylar style) in the signal chain which I replaced. Powered it on and it worked fine on my test bench. I then set it aside for a month or two on the shelf. I got ready to sell it so I hooked it up again on the test bench and all the MOSFETs went up in flames one more time. I have no idea what is causing this, or what is even going on. I did not even have any speakers connected to the amp when it failed the last time. Simply powering it on caused it to fail.

Maybe the PWM controller is to blame. I looked at its output on the o-scope and it is good, so I am still lost.

Your problem is transformer.

So I need to find a short in the transformer, or would it be something like a cracked core?

Mysterious... You could try a meg-ohm meter to test for leakage/bad insulation on the windings...

god the meg-ohm..... That couldn't be brought out at my last place of employment with out a dare to see who could take it at the highest setting. We almost hated to do that maint just because of that.

While waiting for the mosfets, i played with this amp on my workbench. I used a homemade powers upply that i made from an old computer PSU which delivers 12v/19A a while back, so i used this to test.

When i first hooked the amp up, powering up my power supply would give the amp power for about 2 seconds, then i could hear a relay clicking, the light on top of the amp would light up for a split second then my power supply cutting off due to lack of power. I then hooked up my clamp ampmeter, tried the same thing, amp would use about .1amp, then relay click, big amperage surge and power supply cutting off.

I then unsoldered the 11 remaining mosfets, and this time when i put power the amp, the amp it stay at .1amp after relay click, and led stay on. So my guess is that mosfets were bad. Can't wait to get the new ones to test it again! But there is a 1-4 week delay before delivery, and another 5-7 days once they're shipped to get them...

The more i check the ¨pink tape¨ on which the mosfet sit the more i'm sure it needs to be replaced. There is lots of debrits on it, even hairs on it. Everything seems to stick on it so it would probably be easier to just change it. Does someone know the name of this part? Can i buy like a sheet of it and cut it to fit size?

Thanks

Come on guys, no one knows? I've been looking around, some say use mica, other say use silicone thermal pads, some other say don't put nothing, but i'd really like to put the exact same thing that's already here...

Looks like silpad to me. Trying to find one that exact size may be a pickle. Search silpad on Digikey and see if you can find one the same dimension. It would be totally functional to use individual ones for each device. That is how the older amps were done.

Also, do you guys use thermal paste or thermal grease on mosfet? Can i use Artic Silver 5 on it or is there something better?

I think the pad takes the place of that.

ttocs wrote:I think the pad takes the place of that.

Correct, if you are using the pads you do not need the paste. The pads are good for electrical insulation and heat transfer. The paste is only good for heat transfer, NO electrical insulation.

Well on this amp there is both thermal paste/grease and a thermal pad. It could be possible that the amp been opened before me and that someone added thermal paste/grease, i don't know since i've got it like this. Can someone check on his amp if both is used, or only thermal pad?

Thanks!