About the heater circuit of Marshall DSL100HR

[Mackerel]

HI,Bro. Now, the heater voltage of Marshall DSL100HR is 7.3, which is a high voltage value. I have changed the resistor to lower the voltage but it does not change at all. I am changing the resistors R1 and R2, probably thinking that the circuit shown below is the heater circuit. Please tell me if this circuit is the heater circuit. Also, if this circuit is a heater circuit, please tell me where to change the resistors to lower the voltage.

[The Dude]

R1 and R2 are for an artificial center tap. I wouldn't change those. Lowering those resistor values enough to lower heater voltage will draw extra current on the heater windings of the transformer and damage it. Is your mains voltage high?

[Mackerel]

No, It’s 100V

[The Dude]

Is that measurement (7.3V) with all tubes installed? I ask because I've not seen a DSL with this problem.

[Mackerel]

Yeah, installed all tubes

[g1]

Are the DC supply voltages also too high? (power tubes should have about 450V at pin3)

[Mackerel]

Yeah As I recall, it was outputting about 450V.

[nosaj]

No, It’s 100V

Do you have an Export transformer for Japan rated for 100v, since that is what your power grid is? If you have a 120v model transformer your voltages will be skewed.
nosaj

[Mackerel]

It's originally made for Japan, so there's no need to use a transformer to transform it.

[g1]

If it had a 120V setting, that would help.

[The Dude]

If it were a 120V transformer running on 100V, filament voltage would be lower, not higher. It would be nice if there were a 120V switch or primary winding. That would probably solve the problem. You could interrupt CN10 and/or CN11 and add series resistors (about .22 ohm/5W on each side or .41 on one side), but I don't think I'd do it. It's going to add a lot of heat inside the chassis. Probably best to just let it be. It may slightly shorten tube life, but not substantially, IMO.

Edit: g1 snuck in while I was typing.

[Mackerel]

If it had a 120V setting, that would help.

Sorry I don't have a transformer.　<(_ _)>

[g1]

Does it have EL34 or 6L6?

Full service manual here: https://music-electronics-forum.com/...etch?id=976230

[Mackerel]

If it were a 120V transformer running on 100V, filament voltage would be lower, not higher. It would be nice if there were a 120V switch or primary winding. That would probably solve the problem. You could interrupt CN10 and/or CN11 and add series resistors (about .22 ohm/5W on each side or .41 on one side), but I don't think I'd do it. It's going to add a lot of heat inside the chassis. Probably best to just let it be. It may slightly shorten tube life, but not substantially, IMO.

Edit: g1 snuck in while I was typing.

I see. How do I fix it completely?

[Mackerel]

Does it have EL34 or 6L6?

Full service manual here: https://music-electronics-forum.com/...etch?id=976230

Yeah, it have EL34