[A.N. Beal]

Dear John,

Thanks for your suggestions.

1. Resistances checked with valves removed - all about 230k ohm, assumed OK.
2. Reinserted valves, disconnected left channel feedback link - problem disappeared.
3. Now the strange part: I checked all the output transformer connections and they were all correct and the U2 anode connections were also correct.
4. Having failed to find anything in the wiring which appeared wrong, I took your advice and swapped the U2 anode connections.
5. Switched on and ... peace, quiet, no smoke, voltages fine, problem solved.

So thanks very much indeed for your help - I don't think I could have solved this one on my own.

Yes I had been in touch with Matthew about this, so it is the same one he spoke to you about.

Thanks and best wishes,

Alasdair