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Strange BC30 problem

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Hello all,


Picked up a BC30 yesterday and I've come across a problem with channel 2.


It sounds good (will do the cap mod though) but the volume keeps dropping out randomly. It will go real quiet and turn quite fizzy? Then it'll come back to normal and keep repeating.


The preamp valves are the original Chinese cheap ones and the power valves look original too (sovtek date stamp is 02). Rectifier valve has been replaced by a JJGZ34S at some point. I've tapped all the valves and they dont seem to make any noise when powered up.


Is it best to try new power valves to start off with? Looking at some tung sol 5881's. Never had problems with that brand.


Channel 1 doesn't have this problem at all, swapped v1 and v2 but the problem didn't move.


Have also noticed that the gain pot was loose so have tightened that up and reflowed the solder. But if you press on the knob you can hear a pop through the amp. I've ordered a new alpha a1m pot so hopefully that'll be fixed.


Any possible help would be much appreciated!





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