Planet Audio BB1350.1B

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Heres another interesting one for the night. This amp doesnt seem to have any bad parts in it, but when I apply power and ground the internal fans spins by itself very slowly. When I apply rem, the fan spins full speed, and the amp's power LED cycles from Red (Protection) to Green like most Class D amps do during start-up. The trouble is, there no voltage anywhere inside of this amp greater than 13.6v. Theres only DC on the PS Fets, and also no regulated voltage at the opAmps. This amp is not powering up correctly.

KA3525A voltages:

Pin 1: 0.099
Pin 2: 5.15
Pin 3: 0.111
Pin 4: 0.283
Pin 5: 2.186
Pin 6: 3.705
Pin 7: 2.168
Pin 8: 4.88
Pin 9: 5.56
Pin 10: 0.110
Pin 11: 5.10
Pin 12: 0.086
Pin 13: 11.78
Pin 14: 5.11
Pin 15: 11.78
Pin 16: 5.14

I'm seeing +13.36vDC on the power supply gates. No signal just straight voltage.
 
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Yup you nailed it. Fets are shorted legs 1-2. Silly me! Usually I see the the damage and smell the silicon. This amp must have died in it's sleep because there is no noticable trace of the failure.

I also was just able to test some of the outputs. it was tough at first until I removed the clips. A lot of them are shorted as well.
 
I knew my spare MPSW42s would come in handy some day.

Unfortunately I dont think this repair is going to happen. With all that is wrong, I dont think the repair is worth what the amp would be worth for the guy. It needs all new outputs which I beleive are the expensive IRF30n20d, and all new PS Fets which are IRFZ46/48. Plus drivers all around.

its hard to justify an expensive repair + labor for an amp which probably wholesaled for $75.
 
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