Electronics > Repair
Class D Subwoofer Amplifier Repair
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geoffagain:
*edit updated attached schematic

Hi gang,

Have a BKA-130-C Buttkicker amplifier that is stuck in standby mode.

Can anyone help with methodical fault finding please?

Attached pic of board and schematic.

I have component tested the momentary buttons and the the two IRF740 mosfets which are ok.

The board looks to have got hot around the 'remote' connection - I've reflowed the four resistors R426 R427 R428 R169 and transistors Q404 and Q405 which also tested ok with a DMM.

Powers on, but standby light remains red. Pressing power momentary switch I can hear relay click but led remains red and no output.

Am I right in thinking the fault protection is controlled by the irs2153D? I'm not sure how to test.

Harry_22:
Hi!

1. Check voltage at SW105 pin1 =+12V
2. Check voltage at (-) D403 =+12V
3. Check voltage at (+) D403. It grow slowly up to +6V and falls every time you press On (SW105) button.
4. IC403 pin 1. It changes from 0V to +12V or back every time you press On button.

PS
Seems it works if you hear relay. Sorry I missed this.
Harry_22:
Carefully measure voltage between pin 1 and 4 of IC201A.
Next measure between pin 3 and pin 4.

Make sure the amplifier is turned on.
geoffagain:


Thanks for the guidance.

As it happens IC201A on the schematic is listed as a L6569AD

On my board as I mentioned but didn't click its a irs2153D - still a gate driver.

I've attached here another schematic I've found that lists the irs2153D - I'll try and update the original post too.

I'll test it as described in anycase.


Thanks

Harry_22:
Two almost identical diagrams but drawn differently.
The second one is completely unreadable. I mean it's hard to understand.

PS
I attached the first one as an example.
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