Hello.

Last August I acquired an Ashdown MAG200 combo (C410T-200) which was blowing its main fuse. With a light bulb limiter, the 100W bulb was glowing brightly. I posted on another forum and have had some help from Enzo.

I checked for shorts and cold solder joints on the power board but didn't find any. A couple of the power transistors had burn marks so I replaced with the BUZ900P and BUZ905P with ECX10N20 and ECX10P20. Now the bulb is bright initially and then fades to off. The VU meter on the amp is illuminated now.

With the limiter in place, I checked the voltage speaker out and it was 54mV, so I plugged in a speaker but got a loud hum (no bass connected, volumes at zero).

I re-flowed the solder on the larger components including the filter capacitors but it's made no difference.

I'm seeing 46V AC from the transformer and +61.4V DC for V+, -61.4V DC for V-.

Can anyone advise what to try next? This is my first real attempt at repairing an amp other than fixing input jacks.

Photo of board (before replacing transistors) and schematic attached (power board is APC008 on page 4).

Thanks!