KAC-9152D Kenwood - No Power

[kmil]

Hello DIYAUDIO community. I have been very pleased with the wealth of information available on this site. Lots of expert advice and patience with those of us who are not experts. I tried to do my homework so that patience can continue.

I am working with class D Amp that will not power on. I am bench testing with basic multimeter, car battery for 12V source with a 10A fuse in series.

I have attached a PDF doc that contains what I believe to be the most relevant components (with ref desig) for this type of repair. The measured Voltage for the 16 pins on the Driver IC is listed. Also, the measured ohms between leg 2 and 3 on the Output Transisters have been verified (not=0).

This is as far as I could get. Information overload kinda has my brain scrambled on the next step....

Thanks in advance for helping to steer me in the right direction. Let me know if theres missing info needed.

[Alaraune]

Hi! here is the service manual. The site is: Kenwood Kenwood KAC-8102D,8152D,9102D,9152D Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics

[kmil]

Thanks for the link. I've had eserviceinfo.com bookmarked for some time now. Sure is a great resource once you learn how to navigate their site. Unfortunately, I'm in need of a bit more "spoon feeding" to get to the next step.

[blakktalon]

I usually check all the fets the ones clamped to the heatsink, and all their legs(1-2, 2-3). maybe there is an open short between legs one and two? Most often one of them is bad. and is not letting the amp power on. It could be one of the output fets is bad, and triggering the protection circuit to not let the amp power up as well.



If you and your pdf go over to the car audio section, you may get nelp from master yoda himself.

[kmil]

Thanks Blakktalon. I'll try check the for shorts.

By master yoda himself, I'm guessing you mean Perry. That guy seems to be the guru of Amps. I think it was his web site that made my brain overheat.

[blakktalon]

just read the website, and the basic amp part once and a while. Your probably trying to take to much in. I know my brain does the same thing all the time, especially trying to learn to read schematics.

When you get to the voltage regulators, and or current rectifiers. D18, and D20, I Dunno if they look like all the fets. You will get wild and crazy readings. your actually reading the windings of the power transformer.

Thats all I know for now till i remember something else.


If you can afford it, and wanna keep working on amps. I would highly recomend the tutorial. It enough information to keep your head overheating for years to come.

[Perry Babin]

What's the DC voltage on the three terminals of Q3?

Place the black meter probe on the amplifier's ground terminal. Place the red meter probe on the point where you need to measure the voltage.

[kmil]

1) 12v
2) 3.5v
3) 12v

These are the voltages.

[Perry Babin]

DC voltage on both terminals of D4?

[kmil]

p-con side 11v
other side 4.3v

I'll stay close by my computer now.