Hi,
I've bought a used TSL100 and got it delivered today. Problem with this amp for starters was that there wasn't a matched quad in there. There was one EH EL34 in the first socket en 3 Sveltlanas sitting in the other sockets. It seems the Svetlana's were the original tubes in this amp and that the owner (somewhere over the years) changed the first EL34 to something else (??)..
A while back I had a DSL100 with a similar problem, from that experience I've learned to first check the bias before trying out the amp since you don't know where it's been. When I power on the amp, the right pair EL34 bias value is stable, the left pair on the other hand goes past 150mv and going higher and higher. I see the tubes light up blueish and a hum becoming stronger and stronger... Of course I power down the amp before something bad happen
Just to be clear, I've bought a new quad of EL34's for this amp, and I had a used set of 4 12ax7 in storage which I know are good.
I've looked at the PCB but can't discover any burned components.. From looking at it briefly, I've seen the PCB design looks a lot like the DSL100 PCB and I think the bias resistors are R19 and R24 which seem ok (the ones in the DSL were fried because some other part came lose of the board).
Could the unmatched EL34 have caused technical problems in the amp or would that just make it sound weird?
I've read a lot that the TSL100 (this one is a 2001 head) have heat issues causing the solder of the tube sockets to come lose and have bad connections. I'm aware of the wrong resistors in this version of the PCB mainboard. I will replace them but they just make the amp a little unstable, nothing radical like this.
I know the tubes are fine, can anyone steer me in the right direction?
Sander...