[rfeenstra]

I have a friend who's looking at buying this Zenith from a neighbor.  Is a 10A1 worth buying?  they'r asking $100 and it appears to be in ok condition.  Don't know if it's been molested.  I read that the 6X5's are a problem along with rubber wiring.  True?

[morzh]

Some folks here don't have much respect for Zenith, but a black dial Z being what it is and the prices being what they are, plus a 10-tube job, I'd say it is not a bad price. See if you could haggle a bit.

[Paul Philco322]

If restored and playing decent I think someone can make their C Note back. 

https://radioattic.com/item.htm?radio=1370028

Paul

[tbone]

Should be a good performing 1940 radio. Has built in wavemagnet Antenna and an RF stage. You are right that it has the dual 6X5 rectifier arrangement, but that can be dealt with. Just beware it might have rubber wiring, but don’t let the scare you. Just don’t power up till recapped and serviced.

http://www.nostalgiaair.org/pagesbymodel...024676.pdf

[Chas]

Test the viability of the power transformer by removing both 6X5's. Turn on and immediately listen for sizzle noises in the power transformer. Continue to wait for another 10 minutes or so, if all is well no sizzles, smoke bad smell or over-heating, then the transformer is O.K. A seriously shorted transformer would trip the circuit breaker, an open primary (bad power cord, switch), no pilot lights.

Melted transformer potting is not always a sign of a bad transformer but of an overload such as leaking filter caps.

The test assumes that all tubes have no shorted filaments, pilot lights are not shorted and underside wiring has not been tampered with.

Such a test allows for more negotiating room if the transformer is ruined, or a chance to walk away

YMMV

Chas

[rfeenstra]

Thanks guys!

[Arran]

The problem with these is not due to the 6X5 tube, in and of itself, it's the fact that they used a pair of them, and wired both diodes in the 6X5s in parallel in an attempt to get around the maximum current and voltage ratings, in a what would otherwise be a nine tube set with push pull 6V6 outputs. Why they did this is anyone's guess, maybe they thought that the design would make the transformer cheaper since it would eliminate the 5 volt rectifier winding? Or maybe they got a really good deal on a rail car full of 6X5Gs from Sylvania or one of their other suppliers. It was really a case of a bad power supply design, not that the 6X5 was a bad tube, they were used in thousands of small AC and car radios for years, but in most cases they were run at well below their maximum threshold which was 70 ma at 250 volts, and employed 6K6s rather then 6F6s or 6V6s. One easy way to tell if the transformer is bad is by Ohming out the windings, if one side of the high voltage winding is substantially lower then the other, shorted, or is open, the transformer is bad, an AC voltage check could tell your the same, but a resistance check is something you can do at the rectifier tube sockets without risking damage to the radio. By the way, the 10A1 is the chassis number, not the radio model number, which would be something like 10-S-566, depending one which cabinet style it had. Some of these sets also had a faux wood grain on parts of the cabinet, which is a bit of a turnoff for me, much more then a bad power transformer or 6X5 tubes,
Regards
Arran

[Eliot Ness]

Arran is correct, 10A1 is the chassis # and according to the Zenith service manual it was used in 4 different cabinets:

https://www.radiomuseum.org/r/zenith_10s...h10a1.html

https://www.radiomuseum.org/r/zenith_10s...h10a1.html

https://www.radiomuseum.org/r/zenith_10s...h10a1.html

https://www.radiomuseum.org/r/zenith_10s...h10a1.html