IR2011 class D issue

[Lenin89]

Do You want me to zoom in certain area ?

 

[Perry Babin]

Are the 5 large white resistors very low values? Are they, within tolerance?

3 in series with the negative rail and 2 in series with the speaker output?

 

[Lenin89]

Checked. They are all in tolerance. No issues there. very low values, yes indeed = 0.1ohms each.

 

[Perry Babin]

3 in series with the negative rail and 2 in series with the speaker output?

If so, 0.1 ohms seems high.

Are they originals?

 

[Lenin89]

3 in series with the negative rail are 0.1ohms
2 in series with the speaker output are 0.05ohms

They are the original ones.

 

[Perry Babin]

Are you using any limiting on the 12v power supply? Could it be starving for current, causing it to go into protect?

 

[Lenin89]

100А 15v power supply and in addition two AGM batteries. No limiting.

 

[Perry Babin]

Repost the waveform when the amp is distorting but show about 8-10 cycles.

Does the problem get worse when going from 4 ohms to 2 ohms?

 

[Lenin89]

Does the problem get worse when going from 4 ohms to 2 ohms? - i would say stays almost the same...
I've noticed one of the mosfets in the output section (fb41n15d) is getting hot, much much faster than the rest 7....sadly these ones are obsolete

 

[Perry Babin]

Can you swap that FET with one in another bank to see if the heating follows the FET or if it's due to the location?

I'm assuming that you've checked all of the drive circuit components.

 

[Lenin89]

Can you swap that FET with one in another bank to see if the heating follows the FET or if it's due to the location? - this is what i'm doing right now

I'm assuming that you've checked all of the drive circuit components. - i've even changed all the 1n4148 diodes with new ones, new gate resistors just to be 100% sure.

 

[Perry Babin]

Is this the basic circuit you have? I know the driver IC is different but the rest should be similar.

 

[Lenin89]

Okay..,this exact one mosfet is the issue...it's heating up more even at idle comparing to the others, no matter where it is in the board....so now I have to swap all of the 8 mosfets with something else, because I can not find 1 fb41n15d....

 

[Perry Babin]

Do you have any irf3415 on hand?

 

[Lenin89]

at hand only:
IRF1310N
IRF640N/IRF540N
IRFB4227
IRFB5615
a few SSP45N20A

irf3415 - gonna take a few days to deliver.

 

[Perry Babin]

Don't order them. They were common for me. I thought you might have some.

The 5615 might be OK. Could you install them in the bank (all locations in that bank) where you have the problematic transistor?