[legg]

On Mon, 30 Jul 2012 11:17:58 -0700 (PDT), spamtrap1888
wrote:

On Jul 30, 11:01*am, legg wrote:
snip
The non-functioning mixer self-biases at half the schematic grid
voltage value and 2/3 the plate current - but *expect this when input
signal is missing Grid resistor is 20% low with age/dirt. Oscillator
grid resistor seems low in schematic at 22K, but what do I know.

As this is the section that seems to be malfunctioning, I'm wondering
if there's any advice related to the earliest versions of this tuner
that might ease in reviving it. Tubes test functional for heater,
emissions and transconductance, if a little slow to warm up.

Just to clear the decks: I'm assuming there are no date codes on
chassis or PCB that would indicate early or late production, and that
the tube types present match the numbers silkscreened on the PCB, or
the tube diagram inside the unit, if present.

No room for tube diagram. Chassis cover is perforated, chassis base
has standoffs and adjustment ports. This is pre-silkscreen era -
copyright 1956 in foil pattern.

Just seeing a printed circuit in consumer audio surprised me.

Board is PC-A-5, DWG P1702265A

MFR 'Operation and Service Instructions' dated 1956 stops at page 4,
without a tube list or schematic. SAM's is dated 1957.

RL