More on Marshall TSL100

[JC@]

I would like to put 6L6s in one of these, but I can't find that part of the schem in the schems supplied by Marshall at their web site.
Have these amps ever had a version with 6L6 in them? As is, the bias circuit does not have enough range to run 6L6s, too cold.

Thanks in advance.

[Jazz P Bass]

TSL 100 bias circuit

Here is the power board schematic.
The bias voltage comes from D9 & D10, through R77 (10K) & then out Con 1.(pin 1) which goes to the bias adjust pot/ board.

[Enzo]

And generally, at the same B+, EL34s need a lower bias voltage than 6L6s, so if anything, the amp could be too hot for 6L6 rather than too cold.

[JC@]

And generally, at the same B+, EL34s need a lower bias voltage than 6L6s, so if anything, the amp could be too hot for 6L6 rather than too cold.

Enzo at it's best I can get them biased at 12mA per tube. And the paint on two of the old EL34s was a bit charred. ? Could the bias circuit (pots? conector?) be faulty somewhere?

[Enzo]

Pull the power tubes, power up. measure voltages at each power tube socket pin. Is there B+ on BOTH pins 3 AND 4 of all the sockets? What is the bias voltage on pin 5 of each socket? Looking for about -50. Power off. Measure resistance to ground from pin 8 of each socket. SHould be about 1 ohm.