Hi Simon, I am trying to repair an A400 and came across your video. The problem is a rather high dc voltage (134mv) on the left channel. I've checked all the resistors on the left channel and they tested ok. Have set the idle voltage to 20mv according to the service manual but am still getting the dc. Any clue what might be the possible issue? Many Thanks 🙏
Hello Steven, ive watched your videos..im used to work doing this kind of thing many years ago.. I was given one of these amps in for repair after its been past about here and there..I've found it has rustle/low hum in the audio and looked at the circuit diagram plus the last chap who said he replacing many things hadn't do so. Also the bias across the emitter is reading 1.2mv..very low. I'm thinking it should be 12mv or there abouts. Any suggestions would be greatly appreciate. Manythanks. Wayne
If you still have the A-400, Check for cold/dry solder joints everywhere! The A-400 is probably one of the worst offenders for bad solder joints! btw, Your amp looks like the input caps have been changed
