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FERNSEH · 14th Jun 2021, 9:56 pm

Heatercathodeshort wrote:
"Hello David, It is possible that the ultrasonic receiver on the front of the TV has gone weak. I seem to remember early sonic remotes from the colour era slowly becoming faulty and reducing the range. J."
Hi John,
there's lots of components in the remote control amplifier possibly needing replacement and the microphone isn't above suspicion either.

Colourstar wrote: "What does the preset pot do? Is it some kind of sensitivity control?"
Hi Steve,
in a sense it is. The control is the relay current adjustment.. According to the information in the 1961/62 Radio and Television servicing book the adjustment procedure is as follows. "Check that HT voltage is correct, not too high or not too low as a result of mains tap setting or a receiver fault.
With the receiver fully warmed up turn the control fully clockwise and press down the relay armature with a fully insulated tool. The armature should "hold on".
Turn the control slowly anti-clockwise until the relay armature lifts.
Prod the armature a number of times and check that it does not hold down.
If it tends to hold, the control must be further turned further anti-clockwise to ensure the relay does not remain in the closed position."

Bob_Moss wrote: "If you want an EF80, I think I can spare one"

Hi Bob,
thanks for your kind offer, but although I could not find an EF80 at home where the HMV is kept and being serviced there was plenty EF80s in the shop. In fact one was found with the correct production date, late 1960.

DFWB.

14th Jun 2021, 9:56 pm	#54
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: HMV 1920 made in 1960. Heatercathodeshort wrote: "Hello David, It is possible that the ultrasonic receiver on the front of the TV has gone weak. I seem to remember early sonic remotes from the colour era slowly becoming faulty and reducing the range. J." Hi John, there's lots of components in the remote control amplifier possibly needing replacement and the microphone isn't above suspicion either. Colourstar wrote: "What does the preset pot do? Is it some kind of sensitivity control?" Hi Steve, in a sense it is. The control is the relay current adjustment.. According to the information in the 1961/62 Radio and Television servicing book the adjustment procedure is as follows. "Check that HT voltage is correct, not too high or not too low as a result of mains tap setting or a receiver fault. With the receiver fully warmed up turn the control fully clockwise and press down the relay armature with a fully insulated tool. The armature should "hold on". Turn the control slowly anti-clockwise until the relay armature lifts. Prod the armature a number of times and check that it does not hold down. If it tends to hold, the control must be further turned further anti-clockwise to ensure the relay does not remain in the closed position." Bob_Moss wrote: "If you want an EF80, I think I can spare one" Hi Bob, thanks for your kind offer, but although I could not find an EF80 at home where the HMV is kept and being serviced there was plenty EF80s in the shop. In fact one was found with the correct production date, late 1960. DFWB.