Projector questions

[uki]

Hey guys !

I've got this projector, in a really good condition, it does have a PP amp EL84 and 2 12ax7 in the preamp.
The plan is to convert it into guitar amp.

Luckily the schematic could be found, not very clear but almost readable.

To start i got 2 questions(a few more to come), so here it is:

there is 2 things in the left side of the schematic I dunno what it is,

--> top left, that   0A2  or maybe its  DA2

--> and in the bottom left that 90CG

What are those, and that pot between it ?


Thanks in advance!

[rumpus]

0A2 is a  "miniature type cold-cathode glow-discharge tube used in voltage regulator applications." - RCA Receiving Tube Manual, 1971

Drawing a blank on 90CG. But by the symbol, it looks like the same general function.

[SEL49]

https://frank.yueksel.org/sheets/191/0/0A2.pdf

https://frank.yueksel.org/sheets/030/9/90CG.pdf

The 0A2 is a 150v regulator tube. The 90CG is a photo tube. The pot sets the operating voltage for the photo tube. Neither is useful for a simple guitar amp.

[uki]

Thanks guys !!

I've found another schematic and started digging into the device, funny thing, no 0A2 or 90CG in it. Except for the projector lamp and pilot lamp.

the schematic is barely readable, it is a bit different from the previous one.

PT read fine resistance wise

Ecaps are all gone, one side of the OT is open(im hopping its just a broken wire) and one of the power tubes looks suspicious,
one resistor in the power supply area is burned,
what looks like to be the cathode capacitor for the PA tubes looks open, the little cap under that big resistor in the pic.

That combine could cause the OT and possible one PA tube failure  ?