Rockford Fosgate Punch 200.2 Old School Repair

[Mike Stephenson]

I have an old school Punch 200.2 that appears to have a blown mosfet. The amp does play (bridged), but cuts out at about 50% volume. I assume it's going into protect mode or something. As soon as the volume is back below 50% or so, it starts playing again. The part number of the blown mosfet is an MTP50N06V by Motorola. My question is, does it make sense to replace the single mosfet with an identical part#? I've searched online and noticed that the part# is discontinued, but I've seen the exact part on eBay. Or, should I look for a newer replacement part? Also, I've read that I may need to replace several of the mosfets in groups. Should I replace all of the mosfets of the that are the same part number? I've noticed more than one part number for the mosfets. I assume that one part number is for the power supply and the other is for the audio circuit? I will definitely check the resistors and diodes next to the blown mosfet, but are there any other components (resistors, diodes, etc) that I should check? I've attached an image showing the blown mosfet in the upper left side of the image. I'd appreciate any feedback anyone can give. Thanks,

 

[Perry Babin]

Don't buy semiconductors from ebay unless you know for a FACT that they're reliable. Feedback isn't a good indicator.

I'd suggest replacing all 4 power supply FETs with IRF3205s and the 4 gate resistors with 47 ohm (size 0805) resistors. Also order at least 10 of the MMBTA06 and MMBTA56 transistors in case the drivers have failed. Digi-key and Mouser are reliable distributors.

 

[Mike Stephenson]

Wow. Thanks for the quick reply. I just did a little research on Digikey and I do have a few questions.

For the IRF3205s, they come in a few packages. I've narrowed it down to the following two.

TO-220-3
TO-262-3 Long Leads, I²Pak, TO-262AA

Should I get the one with "Long Leads", or just the regular ones?

For the MMBTA56's and MMBTA06's, which Supplier Device Package type will I need? The choices are:

SOT-23
SOT-23-3
SOT-23-3 (TO-236)
SC-70-3 (SOT323)
PG-SOT23-3

I just want to make sure I'm ordering something that will fit in the location.
Thanks again for the help.

Mike

 

[Perry Babin]

You need TO-220. The 263 is different.

For the smaller transistors, SOT-23.

Post links for the ones you intend to buy. Check the links in a different browser before posting to confirm that they work.

 

[Mike Stephenson]

Thanks for helping me narrow it down. Here are the links of what I intend on buying.

IRF3205PBF International Rectifier | IRF3205PBF-ND | DigiKey
ERJ-P6WF47R0V Panasonic Electronic Components | P16869CT-ND | DigiKey
MMBTA06 Fairchild Semiconductor | MMBTA06FSCT-ND | DigiKey
MMBTA56 Fairchild Semiconductor | MMBTA56FSCT-ND | DigiKey

Mike

 

[Perry Babin]

Those will work but you don't need 1% gate resistors. The following will work as well. Order at least a few extras. They are easy to lose.

CRCW080547R0JNEA Vishay Dale | 541-47ACT-ND | DigiKey

Also twist the small capacitors near the power terminals. They sometimes have broken legs. If one leg is broken, they will rotate on the remaining leg.

 

[Mike Stephenson]

Great. I appreciate the help. Thanks again.