Simplistic MosFET HV Shunt Regs

[Salas]

Fat Schottky was tested. Don't know if 1N4007 can help when its only thing you got in hand but will not create a problem either.

 

[merlin el mago]

I have:

Zener 12V 1W
1N5822RLG
1N5383BG
1N4148
1N5819

 

[poty]

It's normal if I connect the SSHV2 without load Q1 gone? VDCin 362V.

Better use a sturdy Schottky diode instead of the Zener (the one near the JFET) that it proved helpful in preventing accidents

The diode helps for short-circuit, not no-load condition.

 

[poty]

NO for:
Zener 12V 1W
1N5383BG
1N4148
Yes for:
1N5822RLG
Probably:
1N5819

 

[Salas]

The diode helps for short-circuit, not no-load condition.

I know, but maybe it was a quick short involved when manipulating so good to have it there anyway

 

[Tubenstein]

Better use a sturdy Schottky diode instead of the Zener (the one near the JFET) that it proved helpful in preventing accidents

Thank you all of your opinion!! Wish my Daniel II will shine again with the new reg!!

 

[Tubenstein]

This actually my cousin project and I have some parts that might suitable for the purpose. I want to know whether the outstage has the same B+ as the first and second stages? Is that 179v??

Do you suggest he put one SSHV2 for the first and second stage and the other SSHV2 for the output stage? I meant per channel.

Also, one power transformer for first and second stages and the other transformer for the output stage.

Just IMHO.Technically - yes, but in the balanced circuits the single point of power for a stage is essential for best PSRR, so I'd not divide the power supply into so many pieces. The first two tubes (4 triodes) form one stage, so - one SSHV, then - tube (double triode) is the second stage which I'd power from the same (first) SSHV. The only stage - output - deserves its own power supply and it can be anything really.
Difficult question, several answers here highlight the differences in the similar designs. But I wonder - why do you leave the -110V supply alone? It is the part of the B+s for the first stages!

 

[Tubenstein]

that attenuator shown in the left diagram cannot be balanced impedance.
The attenuators are inherently not identical impedance. The tapping point/wiper is inherently not equal and this too affects the balance of impedance.
Balanced means balanced impedance and that applies to the connection between modules. It's the connection that is balanced impedance. it's the precision of this balance that attains the interference rejection.

Since I have 2 x ladder type stereo 100K stepped attenuate, and it should be suitable to put this stereo attenuator in a balanced type circuit per side. What about putting this type stepped attenuator in this LS5 MKIII circuit and completely ignore the attenuator arrangement stated on the circuit diagram.

 

[merlin el mago]

Can regulate Vout more or less, Vout is fixed at 285V and max CCS is 21mA, dummy load 16K7.

 

[merlin el mago]

Can't regulate Vout, is fixed to 285V.

 

[Salas]

Q5 and/or JFET could have also been hit

 

[merlin el mago]

Yes are gone, I will replace, thank you.

 

[merlin el mago]

JFET isn't damaged.

 

[merlin el mago]

Changed but still fixed Vout 285V

 

[Salas]

The trimmer works if measured for changing resistance? Q4 is OK?

 

[merlin el mago]

Q4, Q5 & Q6 are OK, time to measure the trimmer.

 

[merlin el mago]

The trimmer is gone replace with one new but still fixed Vout, Q1 DN2540 heatsink is cold.

 

[Salas]

Measure Vgs in each DN. Must be 2-3V if healthy. Also their gate Zeners could be gone & shorted.

 

[merlin el mago]

Q1, Q3, D1, D2, all gone.

 

[Salas]

Catastrophy. Luckily you got that nice desoldering station.