I have a top of the range takamine classical thats causing me grief. Its got a loud hum. The hum is reduced drastically if i touch the guitars input jack with my finger so it seems to be a grounding issue.
I also have a takamine LTD steel string too - that works fine and has done for 20 years now.
I have swapped out the pickup for a new one in the classical...still hums - so its not the pickup.
I have swapped preamps from the two axes...it still hums.
I have resoldered all the contact points.
I think i may have tracked down the problem, but it seems odd...
The shielded wire connnecting the input jack to the preamp seems to be microphonic. If i tap the wire it seems to act like a contact transducer itself....even if its not connected to anything else. So the hum is down that end of the circuit i think. The wire is two conductor plus a shield wire.
Is it possible there is a break in the shiled/earth wire?
Any other things i have not thought of?