recently deceased RF P200-2 :(

[kmarei]

i was running this amp to power 8" subs @ 2ohm each
and it used to get hot, but not crazy hot

now it won't power on
and there is a smell of something burnt
i opened it up and i can see one area that's all covered in black soot
i assume something in that region is busted
any tips?
i assume i'd need to change the 2 FETs below the heatsink on the right (near the blackended are)
i assume those are for the power supply area, as the one on the top left and the one on the left look similar so i think those are for the 2 channels
would also explain why the amp doesn't power up

[kmarei]

i removed the heatsink on the right
and both FETs have the leg towards the bottom of the picture burnt
they are labeled IRFP064N P709XD

[Perry Babin]

IRFP064N is the part number you'll need to order.

It likely also burned the gate resistors and possibly the driver transistors. The gate resistors would be near the first leg of the FETs. The driver transistors would likely be on the driver board near an IC marked TL494 or TL594.

You need to check the output transistors to see if they're shorted. If they are, they're the reason the power supply failed and you'll have to replace those also.

[kmarei]

ok i found the IC (tl494c), the resistors near it look fine, will measure them.
which ones are the output transistors?
the 4 on the middle to top right? (Q1003, Q1002, D1000, D1001
or the 2 on the left side of the amp and the 2 on the top left side of the amp (Q2011, Q2010, Q3091, Q3005

the gate resistors looks toast, will order those.

thanks a lot
you already rescued me on my Soundstream reference 405 that had one bad channel, i fixed that based on your advice, and it's working great and sounding better

[Perry Babin]

The output transistors are the 4 large transistors on the top and left of the heatsink.

When you order parts, also order MMBTA06s and MMBTA56s. Those will replace the drivers if they're defective.

Remove the power supply FETs and power up the amp. You should read approximately 5v DC on the gate resistors for the power supply FETs. If they're defective, you'll only read 5v on the end of the resistor connected to the driver circuit.

[kmarei]

ok i tested the amp with a power supply that puts out 11.5v
i measured the 3 holes for the power supply FETS (after removing them)
0v on S leg
11.5v on D leg
and 4.27v on the G leg
both gate resistors measured 4.27v on both sides of the resistor

does that mean i just need 2 power supply FETs?
i found 2 versions of the IRFP064N
55v 110A 200w
and 60v 70A 300w

which one should i get?

also how do i check the output transistors?
i measured them and the one on the left of each pair measured the same
and the ones on the right measured the same.

[Perry Babin]

I think one of those sets of specs are incorrect. The first one is what I see on the datasheet directly from IR.

http://datasheet.octopart.com/IRFP06...heet-27882.pdf

4.27 is probably about right with only 11.5v.

If no lead placement on any individual transistor read near 0 ohms, they're likely OK.

You should measure the resistance across the gate resistors for the power supply to confirm that they're within tolerance.

[kmarei]

i just searched on ebay for IRFP064N and got this
irfp064n items - Get great deals on Business Industrial, Electronics items on eBay.com!=
so based on the spec sheet you attached its the 55v 100A version

measured resistance of the 2 gate resistors
R1004 read 116ohms
R10 read 62 ohms
not sure what they are supposed to be
when the FETs blew that whole area is blackened so i can't read any numbers on them

do i measure the output FETs when the amp is powered ?
do i have to remove them from the circuit?

[Perry Babin]

I'd suggest that you don't buy semiconductors from ebay. There may be legit sellers but there are also sellers peddling counterfeit parts.

Try THIS.

I don't know if they have a minimum but you were going to pay $10 for 2 so I'd suggest that you order 10.

What are the numbers on the resistors? Clean the soot off with cotton swabs and either alcohol or acetone.

There's no need to measure anything more on the outputs if none had any 0 ohm readings.

[mike49504]

Do not apply power to the amp for testing the output transistors.

Set your multimeter to ohms place black probe on leg 1 and red probe on leg 2 (middle leg) then place black probe on leg 1 and red probe on leg3. The place black probe on middle leg and red probe on leg 3.

Post your results as followed

1-2:
1-3:
2:3

You can leave the outputs inside the amp.