Rockford Punch P600x4 PS failure

[Dr Zeus]

I'm not positive on the identification of the PS components.

All PS fets are damaged. Looks like they are IRF1404 but I'm not totally sure. I would think IRF3205 or similar might work here in this amp? Not totally sure. 51ohm gate resistors are measuring OK but need to be replaced.

TL494 IC with several buffers. A few of them are burned and not recognizable:

Q103: ??
Q104: 2A?
D105: 5D
Q105: 1A
Q106: 1A

Is there a schematic available for this one?

https://www.crutchfield.com/S-oml7d...C_Wa2scYmqp86MxlQXGmHy6Y3RjQlgYhoCqucQAvD_BwE

 

[Perry Babin]

If those are drivers, the ones with the collectors connected to ground are PNP. This should be a typical Rockford drive circuit like those used in most any of their TLx94 supplies.

The 1404s are rated for roughly twice the current of a 3205 do to having an Rdson of 1/2 that of the 3205. I'd use the originals.

With 51 ohm gate resistors, I'd expect the IRF1404Z due to having lower Ciss.

 

[Dr Zeus]

OK Im actually out of IRF1404. I can order them, or since I have to change the drivers/gate resistors; I may try IRFB7437. I believe IRF1404 and IRFB7437 are interchangably used in some Brazilian designs with drive modification.

This amp is a classic Class AB. Its rating makes me wonder why they ever used IRF1404 to begin with as its only 75w per channel amp.

 

[Perry Babin]

I don't know how many FETs they're using.

 

[Dr Zeus]

This amp has 4 fets in the supply. The case will only sync the 4 fets but the circuit board actually has provision for 6 fets maybe for the P1000x

 

[Perry Babin]

For a 600w amp, I'd expect the 3205s to be enough. You'll have to make the executive decision on what to use.

 

[Dr Zeus]

I replaced the 1A and 2A drivers. Then put in (4) IRFB7437 FETs and guessed with 10 ohm gate resistors. Amp seems to be absolutely fine idles at 1-1.25A with the bias turned down between 9-15vDC.