They used IRF3205 in the power supply with a 68 ohm gate resistor. I would use a 47 ohm gate resistor to replace the originals and install new power supply fets. Be sure to replace the driver transistors as well marked 1A and 2A or 1G and 2G. There are 4 of them next to the PWM chip marked TL494C. I would also check the outputs likely some or one is shorted.
When you refer to "N" and "P" channels fets, those are outputs. The 501S used IRF540 and IRF9540 for the outputs.
Rockford only used IRFZ40's in some of the older DSM amps but did not use them for long. They used BUZ11, IRFZ40, MTP50N06V, MTP75N05HD and a couple others.
When you refer to "N" and "P" channels fets, those are outputs. The 501S used IRF540 and IRF9540 for the outputs.
Rockford only used IRFZ40's in some of the older DSM amps but did not use them for long. They used BUZ11, IRFZ40, MTP50N06V, MTP75N05HD and a couple others.
Stay with the IRF3205 and change the gate resistors (hooked to the gate leg of the IRF3205) to 47 ohm. The are smd 0805 pakage. Then change the 4 driver transistors as well.
If the supply has failed replace everything so it is reliable. The supply failed for one or more reasons, determine those as well. Either reverse polarity, or shorted output fets. If the output(s) test shorted remove them from the circuit before powering the amp or you will take out the supply again.
If the supply has failed replace everything so it is reliable. The supply failed for one or more reasons, determine those as well. Either reverse polarity, or shorted output fets. If the output(s) test shorted remove them from the circuit before powering the amp or you will take out the supply again.
Using a small fuse (10 amp) or a current limiter in the B+ line AND having all transistors tightly clamped to the heatsink will greatly reduce the chances of damaging new components when applying power.
If you replace the output transistors, set the bias pot for the repaired channel to the fully counter-clockwise position before applying power.
If you replace the output transistors, set the bias pot for the repaired channel to the fully counter-clockwise position before applying power.
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