Kicker KX1200.1 Green board - Need Schematics or parts help - they are burned/sanded

[KyferEz]

See image with parts circled. I have burned parts I need values of so I can replace, designators the best I can identify are:

R223, R203, R559, R323, R303 (I think), U508, U??? next to U508, R559

Schematics would also greatly help; I found a schematic at KICKER KX1200.1 SCH CAR POWER AMPLIFIER Service Manual download, schematics, eeprom, repair info for electronics experts but it's not clear enough to read and I don't know if it's the green or red board.

Amp goes instantly into protect mode. I know Q221 is shorted and figure the 2 ICs are bad as well.

If anyone knows of a reason for this to happen so I can try to identify all failed parts please let me know. I want to try to get all the parts I'll need in one order. I suspect that the Q221 failing is the cause, but just thought I'd ask. All other output FETs test good.

Thanks!

 

[Perry Babin]

Did you download the diagram? Wait for the 'processing' under the image to change to 'get manual' and download it.

 

[KyferEz]

Thank you Perry. It never changed on my PC. Tried it on my phone and it worked fine.

Know if that is the correct schematic for the green board?

 

[Perry Babin]

If the circuit board designations match, it's for the amp you have (but maybe not for the exact revision). Compare multiple resistor values between the diagram and board to see how it matches up.

 

[KyferEz]

Perry,

Thanks again, schematic looks right.

U508 is listed as B52 and U509 as F16. What would they be? I have been unsuccessful searching digikey/mouser.

 

[Perry Babin]

They are the MC14060B (16 pins) and LM361.

This is a similar amp with the part numbers:
http://www.bcae1.com/temp/bp1200p1_sm.pdf

 

[KyferEz]

Perry,

What would you recommend as replacements for the 2SA1381 and 2SC3503 that can be sourced from mouser/digikey or another reputable supplier? I found a few recommendations, such as KTA1381Y and KTC3503Y or BF469/BF470 but none readily available on mouser/digikey.

I could just order from ebay but would rather avoid the high risk of fakes.

Thanks!

 

[KyferEz]

So in addition to those, looks like Q504 (C4373) and Q505 (A1661) are also bad. I would have to pull them to be sure as it's not total shorts, but very low diode test readings on both of them for 2 pins. Makes sense they would be damaged because they come before the transistor pairs that had the short.

These are looking to be even harder to find as they aren't even on ebay.

 

[KyferEz]

Closest I can find for substitutes for the C4373 and A1661 are FMMT624 and 2DA1201Y-7

What do you think?

 

[Perry Babin]

Give it a day or so. There is a kicker tech that sometimes helps here. He could give definitive answers.

For the larger transistors, the KSA1220a and the KSC2690a would be my choice.

For the smaller transistors, the 2SB1260 and the 2SD1898 should work.