i a few month ago tried repairing this amp, i have since then made progress and found the problem.
square wave at power stage mosfets leg are fine without mosfets in and with them in the square wave will not come down to ground propertly. ive checked the pulldown resistors which are 1 10k ohm resistor per 6 mosfets, when replacing the pulldown resistor with a bigger 1k ohm resistor the square wave is now present with one mosfet and after installing mosfets one after the other the square wave gradually dissappears. gate square wave on buffers are present all the time. buffers where originally c2814 but where replaced by bd237 but did not make any difference. any thoughts?
square wave at power stage mosfets leg are fine without mosfets in and with them in the square wave will not come down to ground propertly. ive checked the pulldown resistors which are 1 10k ohm resistor per 6 mosfets, when replacing the pulldown resistor with a bigger 1k ohm resistor the square wave is now present with one mosfet and after installing mosfets one after the other the square wave gradually dissappears. gate square wave on buffers are present all the time. buffers where originally c2814 but where replaced by bd237 but did not make any difference. any thoughts?
10k resistor on blue mosfet, and 1k resistor on red mosfet. this is with drain leg out of circuit, with it in the power surge is to great.
this is also with the rectifiers out of circuit.
measured the squarewave frequenzy to about 35khz which i think is within margin.
measured the squarewave frequenzy to about 35khz which i think is within margin.