Old 5A5 field coil TV front pro. Grid leak bias question

[chopstuck]

I have an old 5A5 TV Pro I recovered and was restoring.

I got pretty far and just can't get the last bit of gain out of it.
It sounds OK if I jumper two preamp channels but with just one channel it sounds anemic.
I had checked and replaced all of the nasty wax caps put in new Sprague 22mfd caps in the PS.

The b+ rail with field coil sits at 389v . Plates at 384v and screens at only 335v.

I was checking voltages, found the PI plates at 231v and 51 v.
My first experience with grid leak bias has the grids at -0.4 and -0.5v and the plates at 65v.
Is that in the ball park ?

I have no voltage chart for reference.

Amp sounds weak , I'm sure it should sound better than this.

[printer2]

On a 5B6 Bassman. A little different but something to compare to.

I used my decade resistance box to determine that 1k for the 1st dropping resistor will give me 390v on the screens with 396v on the plates. That also gave me 219v on the plates of the 6sl7 and 157v on the plates of the 6sc7, which seem to be in the ballpark.

https://tubeamparchive.com/viewtopic.ph ... 8ba672149a

[chopstuck]

Finally got my TV front Tweed Pro all sussed out.

Someone, (many, many moons ago) wired the PI socket for a different dual triode by switching the #1 and #3 pins.

I was only getting about half a waveform as the inverted signal from the 1st PI stage was fed to the shield of the tube.

Now voltages look better and the amp packs a mean punch. I still had low voltages on the four preamp plates but under closer examination,
I saw that each pre amp tubes' plates were wired in parallel in the early 5A5 with a shared 250K plate resistor.

Well, I've had my microscope out this week and have been finding out all kinds differences between the different tweed generations.

Pre-classic ,non HRM pre-Skyliner tone stack notwithstanding.