Kenwood KAC-X811D, Low power output

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Hi Guys,

I'm new here and I would like to fix this my self, so I'm really hoping someone can help me.

I have a Kenwood KAC-X811D it WORKS! but it has very low power output. I think some FETs are gone.

I have it all set up right, gain, volume, speaker, power wire.
I have opened it up and I don't see any physical damage.

I think it might be the power FETs Q57,58,60,61,64,65,67-70
or the amp FETs Q48-51

Do I have to remove them to check them?
 
The amp is hooked up 2ohm to a 300watt RMS woofer. If this was working correctly it should be destroying the woofer, but it hardly moves, sounds like ~100watts.

I never thought if I asked for help I would get help from Perry Babin... I have been reading your entire webpage religiously over the passed few months. Thanks!
 
When it was new it was running a 15inch at 2ohms until something happened and it stopped working. The speaker was fried, there was no continuity in the voice coils. I removed the system and put this amp away for years. Now I dust it off and hook it up to a 10inch and its like this, very low output. The 10 is only rated at 300rms, the amp is rated 919rms. Am I crazy? This amp should be pounding! I barley hear it over the stock system. The head unit has 2.5v outs and the gain on the amp is set to around 1.5V just so i can barley hear it at normal volume.
 
To determine if the power and ground connections are good, you measure the DC voltage across the B+ and ground terminal of the amp. If the voltage remains well above 12v with the engine running, there isn't a serious problem with the power connections.

When you measured 35v AC across the speaker terminals, was the speaker connected?

Are you sure that you have the positive and negative of the terminals on the speaker connected correctly?

If you connect only one coil, does it get louder?
 
First thing I checked was DC voltage across the B+ and ground terminal of the amp. 12.5V car off. 13.5 with car on.

35v AC across the speaker terminals, the speaker was NOT connected and gain was lower then 2.5V, it was set around 3V.

I have tried changing the +ve and -ve. I will double check.
 
Speaker wires are fine... all + are attached to +. Amp to speaker terminals. I have also tried to flip the phase switch.

I'm not willing to only hook up one coil... how my speaker is it a lot of work to change that back and forth. I believe it was louder when it was hooked up in 8ohms though.
 
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