30-07-2018, 08:38 AM
I've been reading this thread with interest,having restored a TMB 272 last year which I'd had for 30+ years!
It needed the usual recapping and a few other things doing, including a respray and replacing the Rexine covering.
Mine shows a little snow, particularly on channel 1 with the contrast control at maximum,you can get a small increase in gain by shunting V1 cathode bias resistor,33 ohms with a 0.01uF capacitor (not too critical a value), there should be some hiss from the loudspeaker as well.
Change or at least check the video detector diode,its underneath feeding V3(6F1valve) grid via a choke and a 150 ohm resistor.Make sure the contrast control isn't open circuit.
Valve pin/holder contacts may need a clean,rock the valves and see if there's any cracking/variation.
The IF/tuner must be working after a fashion if you're getting some FM signals,tuner valves are indeed ECC84/ECF80.
Good luck!
Hugh
It needed the usual recapping and a few other things doing, including a respray and replacing the Rexine covering.
Mine shows a little snow, particularly on channel 1 with the contrast control at maximum,you can get a small increase in gain by shunting V1 cathode bias resistor,33 ohms with a 0.01uF capacitor (not too critical a value), there should be some hiss from the loudspeaker as well.
Change or at least check the video detector diode,its underneath feeding V3(6F1valve) grid via a choke and a 150 ohm resistor.Make sure the contrast control isn't open circuit.
Valve pin/holder contacts may need a clean,rock the valves and see if there's any cracking/variation.
The IF/tuner must be working after a fashion if you're getting some FM signals,tuner valves are indeed ECC84/ECF80.
Good luck!
Hugh