Rockford Punch 200x2 amp - needs repair

[HeavyD'sCustom]

Ok have another amp broken by my nephew, this one is a Rockford punch 200x2.

Its a 2 channel and one channel seems to work ok, and the second channel doesnt put any music out but it does punch the sub cone out all the way! (if that makes sense) Seems like all it does is push power at full only, and adjusting the gain does nothing.

On a side note: I told my nephew not to use his stereo until we replace the wires.

the first pic is of the resistor that looks bad, on the second channel.



The second pic is of a resistor on the good first channel that looks like it has a bubble - is this normal??



back side of channel 2




mor pics to come.

[HeavyD'sCustom]

top side of channel 2



top side of channel 1



bottom side of channel 1

[HeavyD'sCustom]

pic of channel 1 resisstor with bubble

[Perry Babin]

The channel 1 components are likely OK.

Pull the 0.1 ohm source resistors in the blown channel and check all of the resistors marked 100, 200 and 620 (should be one 620 resistor for each source resistor) in that channel. List the ones (ex. R125, R150...) that are out of tolerance.

At least one of the output transistors in the blown channel has failed. You should replace all 6 in that channel. You should also replace all of the source resistors in that channel. Mouser:
LVR03R1000FB12

[HeavyD'sCustom]

ok all of the 100's I checked were 0.010
and all of the 620's I checked were 0.061

of all 6 resistors i pulled 5 were 0.000 (closed) and the burnt one was 0.135.

and one IRF540 was 0.000 (closed) on all 3 pins.

[HeavyD'sCustom]

and the 100's are R280, R252, R200, R270, R250, R287.

and the 620's are R201, R273, R272, R270, R211(?)

[Perry Babin]

What about the resistors marked 200?

Why do you have the meter set to that range? At a lower range, it's likely to be more accurate.

[HeavyD'sCustom]

ill check the 200's friday, my eyes got tired.

[spooney]

i have this exact same amp on my bench right now . similiar problem as i have a blown channel but it took out the power supply as well.the power supply fets are MTP50N06 , does anyone know if RFP70N06 or HUF75337P3 will work in place of the blown ps fets. just trying to get it going with what i have on hand

[Perry Babin]

Either of those should work. Before you power it up fully, connect only remote and ground and confirm that the gate drive voltage on the leg of each of the power supply FETs is ~5-6v DC. If you have one or more that's significantly higher or lower, the driver transistors may have failed.