Found a poor lonely Admiral 9" B&W hybrid set today

[Jeffhs]

Originally Posted by mr_fixer

I found a date code of 7126 on the main electrolytic cap which i guess this was made around 1971-1973?

Your set was likely made between the years you mention, since it has "instant play". Many tube-powered televisions of the '70s had this feature, which kept the tube filaments on even when the set was off. This permitted the TV to come on almost immediately after it was turned on, almost like a solid-state set.

Instant-play (also known as "instant on") was banished in the late '70s due to concerns over energy waste (remember, this was the decade when the watchword was "conserve energy") and, secondarily, some people worried that any TV with this feature could be a fire hazard since the tube filaments were on 24 hours a day, even though the TV itself was off. The power switch only controlled the B+ (plate) voltage to the tubes.

Another problem with the instant-on system was that, if the instant-on diode across the power switch would short due to a lightning strike, etc., the TV would remain on, even if the switch was in the "off" position. Many people got around this by either using a switched outlet for the TV or simply unplugging the set from the AC outlet when not in use. The instant-on diode would often be removed (at the owner's request) by a technician when the set was in for repair, but this of course eliminated the instant-play feature.