Amp Repair ppl..Little help.

[edzy 10+ year member]

Ok, I got this amp im trying to fix. MMats D200

Problem is the replacement mosfets I got from digikey may or may not have been the right ones.

See, I only replaced 2 out of the 4, and as soon as it powered up, the 2 new ones smoked.

So I am going to try again to replace all 4. Just want to make sure I get the right fets. So if someone could link me to the ones i need, that would be a big help.

Thanks.

The one with the red high lite was the original. The other one is what I used from digikey.

2 old ones and 1 new one.

Old one.

New one from Digikey.

Click to read more...

 

[ampjunkielikeme 10+ year member]

you will have to replace them all at the same time, not just the bad ones ,the gate resistors have to be changed also.....you got a pic of the board? i would rebuild the whole power supply

 

[infamous_e46 5,000+ posts]

Werd let ^^ this dood fix it he is a beast

 

[IDSkoT 5,000+ posts]

you will have to replace them all at the same time, not just the bad ones ,the gate resistors have to be changed also.....you got a pic of the board? i would rebuild the whole power supply

x2.

But, I believe that each component has to have the same specs / produce the same output as the fet before. I know amps are really finicky.

 

[ampjunkielikeme 10+ year member]

oh yea , you have to find the equal replacement parts....the last mmats amp i had was the same way , i couldnt find the original part number stamped on the burnt ones???

i would bet db-r would know about those parts....thats who i contact when i have a questions...

 

[edzy 10+ year member]

Excuse the large pis, but may be better to see.

The ones on the top all had 12 volts in/out when tested live.

The 4 that are missing are at the bottom left, near the power supply. Also i noticed there is no ohm reading or continuity on any of the leds. There is 12 volt on one leg, but not the other.

I was running it at 1 ohm when it smoked. Its only 2 ohm stable...Ya i know, But was just using it for a show for burps at 1 ohm. It did well for a while, but just 1 too many tries.

 

[edzy 10+ year member]

So these are the originals which are no longer available.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=497-2778-5-ND

These are the replacements that are offered.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=497-3201-5-ND

Is there any thing anything else that may need replacement due to a fet blowing?

 

[IDSkoT 5,000+ posts]

I'm impressed with MMATS build quality. That's a nicely done board.

Is it US made?

 

[cx-7heaven 10+ year member]

I see a smallish cap in the center of the board that looks scorched. It's the hourglass looking one. I would really let a pro repair it, without proper test equipment, you will never get that thing going.

 

[ughhibye 10+ year member]

I'm impressed with MMATS build quality. That's a nicely done board.Is it US made?

how the hell are you in south florida and dont know the answer to that question

 

[edzy 10+ year member]

Yes it is US made. Thats why I ran it at 1 ohm for burbs. Quality. Normaly I wouldnt push an amp beyond its realm, Bu I thought it could take it. lol.

And those hour glass shaped things? You mean resisters?

Ya, they are all fine.

 

[ampjunkielikeme 10+ year member]

did you use any insulator pads on the new parts you installed ?

 

[IDSkoT 5,000+ posts]

how the hell are you in south florida and dont know the answer to that question

Because I'm not into SPL comps... or any comps for that matter.

 

[edzy 10+ year member]

yes, and some new therm compound. Like I said, I tried replacing just 2, But am now going to replace all 4.

So What I'm asking

Is that replacement part suitable.

Is there anything else that should be replaced while I'm at it.

I may not be able to diagnose what the problem is, But am willing to try changing the most common parts that smoke when an amp is driven below its ohm rating.

Like mosfets

and ?? whatever else is prone to failure.

I figure $30 spent on part is worth a try before sending it in for $100 to MMats.

So anything else to buy before i go ahead with the order?

Or just do the fets and go from there?

Thanks.

 

[Ge0 10+ year member]

Those are 80 amp, 60V N channel FETS. You don't need an exact replacement, just something with those ratings. ST has tons of options as does Fairchild, International Rectifier, Infineon, On Semi, etc... Make sure you replace all FETS in the power supply primary. They should all be the same type.

I'd check the output stage if I was you. Something caused the FETs to fail. Could have just been the PSU, but, an output may have shorted which took out the PSU too.