stereo troubleshooting advice

[firemedic]

I've decided to try & fix the 1962 RCA Victor console stereo I just acquired, since it's in decent shape. I've replaced the paper caps, installed a grounded plug, and fired it up; AM & phono sound OK but the FM channel has very low volume. Stereo FM is even lower. I know nothing about RF amplification, so I'm gonna retube the whole FM signal. Does anyone know a good forum for dealing w/ these things?
   

[firemedic]

Here's the schem, Thanks PRR & dummyload!

[firemedic]

Well it's about as fixed as I need it to be, pretty much the same troubleshooting rules. Nominal voltages, basically, are what you need to fix anything.
I replaced an open screen resistor on the FM limiter. Whatever that is.
The phono sounds fantastic (even my wife notices the tube difference), I rigged it to connect to iPod or CD player w/ a 1/8" aux jack, & the FM works OK. Done. Before the new tubes even got here.

[DummyLoad]

Well it's about as fixed as I need it to be, pretty much the same troubleshooting rules. Nominal voltages, basically, are what you need to fix anything.
I replaced an open screen resistor on the FM limiter. Whatever that is.
The phono sounds fantastic (even my wife notices the tube difference), I rigged it to connect to iPod or CD player w/ a 1/8" aux jack, & the FM works OK. Done. Before the new tubes even got here.

congrats.   

--DL

[PRR]

To get FM you want a clipped signal. (You only want transmitter "pitch", not "loudness".) You do this by running a pentode at low screen voltage. If resistor is open, screen voltage is zero, signal level is clipped to zero, and that don't work at all (except by sneak paths).

Hoo-ray for finding the fault.