That's what I was afraid of. This is why I prefer tube stuff any day of the week.

I've got spare Zenith tuners of that vintage, maybe the transistors from them would work in yours...If you have the service info and do enough online cross referencing you will probably find a sub for a few cents at your local Radio Shack or 100 for 50 cents at a online parts house.

Zeniths of this era occasionally have intermittent transistors. Usually most sets have one at most...Change it and they will be fine.

It could still be the IF cable - the shield wire will open and cause problems. A simple sup of the cable might be easier than tearing into a tuner.

IF Cables were on our "save" list when junking a set - they were a savior many times. Maggies and Zeniths seemed to eat them - most likely the flexing from pulling the chassis or dropping the tuner to clean it.

Those RF amp transistors inside of the tuner's were a problem in several different model sets. Usually they opened up or shorted when someone walked across a carpet or something similar and had a static change built up on them, and then touched the rabbit ear antenna or the antenna terminals or leads. There not that hard to replace, just have to take out the tuner, remove the shield. and a good eye for soldering. Most of them have 4 leads, a ground, and of course the E, B, C.

Might have been a cable or outdoor antenna set when it got hit by lightning (or nearby discharge). That will do it. My guess is the first RF amplifier (probably an FET) is fried.

Also check the 100 ohm (brown black brown) resistor Called out as R19 by Zenith, may be a different callout in the Sams) on the tuner. Zenith mentions it as causing snowy pix on all channels.

Keep in mind that the problem is intermittent. One minute the picture is perfect, and the next thing you know, it's snowy and distorted.

I've had intermitent video out put transistors in Zeniths of that era. Screen would change tint towards a primary. Damn thing bugged me for years cause it would not stay bad long enough to meter for a source...Eventually it did and I confirmed my suspicion by switching the three color video out transistors around...When the primary color of the intermittent changed I knew I'd found the culprit. Was mechanically/electrically sensitive too a smack would sometimes fix it, sometimes adjusting the tuner would fix it.

Indeed, almost any component can become intermittent, including solder joints as well as active components. Sometimes heating, cooling or mechanically stressing the suspect part will provide an answer, sometimes "blanket replacement" in the suspected area of the circuit is necessary. There is also a possibility that the problem is further downstream, like in the IF amp or AGC circuits. Can you substitute another tuner or do you have a pattern generator that can provide an IF output, and eliminate the tuner from the test?

jr

First off can you get the pix back by hitting, moving
tuner etc ?? OR once snowy do you have to shut off
& cool down to get it back ? Also is it clean snow like
an OTA fringe station ? Last time this came up here
it was just the external matching transformer !!

The set almost has to have a Zenith SGVG tuner that
is good cause its easy to service. BUT I would NOT change
the RF amp without proof. Too many things can go wrong.
Much more info & trouble shooting are needed first.

73 Zeno:smoke:
LFOD !

Danny replaced the transistor in this thing's tuner yesterday, and the picture is very much improved. However, it still does its thing where it distorts and gets snowy every so often. More often than not, it is a perfect picture though.

May want to try another channel. I have a table CCII that randomly flakes out on 13, but will go all day on 3.

IIRC there was also a 'lytic in the AGC that caused snow on these.
Not on a board but on the chassis.

73 Zeno
LFOD !

I think it's a mechanical problem this time. If I have it on channel 4, and it flakes out, all I have to do is wiggle the knob.

Have you tried giving the tuner a good shot of tuner cleaner? If your set has a turret strip tuner as do most Zeniths of that era, that may cure the problem. The channel strip itself could have dirty contacts, but a good cleaning will get the others as well. The only thing I'd watch is the price and/or availability of tuner cleaner these days. The last can of tuner cleaner I bought from Radio Shack in 2002 or so cost about $8; now, almost 15 years later, it could be a lot higher, if you can find it at all anymore.

BTW: How on earth do you find the room for all those TVs you have? :scratch2: I would think you would be just about out of room for consoles by now, especially since you have your '63 Admiral three-way roundie and now a second Zenith. The Admiral looks by far to be the largest of your consoles.