Leak Delta 30 Amplifier - One Channel Down

Wage Slave

2010-09-30 1:22 pm
I bought a Leak Delta 30 about 4 years ago on ebay and took it to Japan with me. I didn't think I would use it much but in fact I really like the sound it produces. More than my Quad 303 in fact.

Anyway, one channel has gone down. I have tracked the fault down as far as it being on one of the pre-amp boards because if I swap them over then the other channel dies and the previously dead one comes to life.

The channel is not completely dead but almost. At full volume there is a very weak sound and a bit of hum. I think the sound gradually became distorted and faded away.

Sending the board back to England for repair looks prohibitively expensive as I can buy a working amp for £30 or so and get someone to pull the boards out and post them to me.

However, I would like to fix it if possible. I can solder/unsolder and use a multimeter and there is a circuit diagram here

Can anybody offer any tips? I was thinking of starting with the electrolytics as they are cheap, available locally and are known to fail. Any other thoughts?
I would first check all the voltages as shown on the diagram. This should give you a clue to where the problem is. If these are within 10% or so then change the capacitors. Look over the rear - copper side of the board carefully. The problem could be a dry solder joint or a crack in one of the tracks. Again the voltage readings should give you a clue where to look.
Thanks Bone. I have examined the board very carefully and did find a few dodging looking joints. I fixed those but with no result. I'll have another careful look for cracks.

This id going to sound like a stupid question but how do I measure the voltage with the board in place? With difficulty I suppose :). Take the board out, attach crocodile clips and replace the board maybe?

Anyway, will crack on with that. Thanks again.