Bad Cat Black Cat 30R Low B+

[g1]

What about the pin2 grid voltages?

[bobloblaws]

What about the pin2 grid voltages?

They all show roughly the same, initially they were around 6.7V but appeared to be steadily increasing so when I shut it off after two minutes or so it had climbed to around 7.3V.

[vintagekiki]

There is no salvation from the horror.
Let someone to try draw right schematic.

[bobloblaws]

They all show roughly the same, initially they were around 6.7V but appeared to be steadily increasing so when I shut it off after two minutes or so it had climbed to around 7.3V.

Should be 0V on cathode bias, right? Coupling cap? I'll look into it.

[bobloblaws]

There is no salvation from the horror.
Let someone to try draw right schematic.

I'll throw you a bone. This is what I've completed so far.

[tubeswell]

I'll throw you a bone. This is what I've completed so far.

There's a mistake in the LTP. The cathode bias resistor is on the wrong side of the 2 x 1M grid leak resistors

[bobloblaws]

There's a mistake in the LTP. The cathode bias resistor is on the wrong side of the 2 x 1M grid leak resistors

Good catch! Here it is revised.

Generally speaking, this is obviously still very much a work in progress.

[vintagekiki]

I'll throw you a bone. This is what I've completed so far.

With your permission a little help to a friend.
If it's easier for you, look at the layout
https://music-electronics-forum.com/filedata/fetch?id=911249

[bobloblaws]

With your permission a little help to a friend.
If it's easier for you, look at the layout
https://music-electronics-forum.com/filedata/fetch?id=911249

That may come in handy, thank you.

[vintagekiki]

I'm here to help

[tubeswell]

Good catch! Here it is revised.

Generally speaking, this is obviously still very much a work in progress.

PI master grid and slave triode grid is still confused

[vintagekiki]

PI master grid and slave triode grid is still confused

Matchless dc30 pwr
http://www.prowessamplifiers.com/schematics/post/matchless_dc30.pdf

[tubeswell]

Matchless dc30 pwr
http://www.prowessamplifiers.com/schematics/post/matchless_dc30.pdf

And its clearly still wrong ...

The tail resistor should be grounded (or ground referenced to an NFB loop). Instead the LTP cathode is grounded (the way its drawn in the OP's schematic)

[Helmholtz]

They all show roughly the same, initially they were around 6.7V but appeared to be steadily increasing so when I shut it off after two minutes or so it had climbed to around 7.3V.

Ok, now we're getting closer.
So we have unwanted positive grid voltages. There's no doubt that this causes the high cathode currents and low B+.

Please proceed as follows:

1) Measure socket pin 2 voltages with all EL84s pulled.
2) Make sure that the junction of the two 220k grid leaks is well grounded (0VDC).
3) Lift both 47nF coupling caps and remeasure socket pin 2 voltages.

[vintagekiki]

And its clearly still wrong ...

The tail resistor should be grounded (or ground referenced to an NFB loop). Instead the LTP cathode is grounded (the way its drawn in the OP's schematic)

Schematics Matchless dc30 pwr is correct.
http://www.prowessamplifiers.com/schematics/post/matchless_dc30.pdf

Compare
http://dealers.korgusa.com/svcfiles/ac30p1.pdf

DC30 and AC30 do not have NFB

[Helmholtz]

I think the 100k is the tail resistor and is grounded together with the upper PI input (assuming there is no NFB).

(Using a continuity tester and/or Ohmmeter can be a big help in finding hidden connections.)