Advice for buying a tube-era TV?

[vintage.digi]

I’m considering driving this weekend to inspect and hopefully buy a 50s TV, and this is older than the majority of sets that I’ve dealt with in the past. What do I need in order to safely test it? Do I need an isolation transformer?

The seller posted a picture showing static and says the photo was taken yesterday. I can take something to display a picture pretty easily. I do have a tube tester but if the whole unit is working then I wouldn’t think I’d need it.

I briefly had a Predicta once, but the second time I plugged it in, it started smoking, so I sold it to someone who had the knowledge to service it. That wouldn’t just be due to the hot chassis, would it? I don’t think home users had isolation transformers at the time these were in use.

[Username1]

I think that if they posted a picture of it working, then it's safe to just ask to see
it turned on like in the post. If it comes on, and the screen gets snow in reasonable
brightness, and seems clear and sharp, and you find it's worth the price in your
eyes, then just buy it and go home..... If it don't work when you get there,
or it smokes & sparks then if you still want it buy it and go home.
If the screen lights, it gets snow, and sound has audio snow then
your doing good, At this point all the stuff that is hard to get
is currently working, buy it and go home..........
Take a flashlight, peek inside and see if there
is a brightener on the picture tube, That
would be a downer, but not always a
no sale condition..... Your choice..
Variacs are for Pu$$ys.....
Just plug it in & turn
it on.....



PS don't break the neck off the tube getting it into yer house.....


.

[Tube TV]

Originally Posted by vintage.digi

I’m considering driving this weekend to inspect and hopefully buy a 50s TV, and this is older than the majority of sets that I’ve dealt with in the past. What do I need in order to safely test it? Do I need an isolation transformer?

The seller posted a picture showing static and says the photo was taken yesterday. I can take something to display a picture pretty easily. I do have a tube tester but if the whole unit is working then I wouldn’t think I’d need it.

I briefly had a Predicta once, but the second time I plugged it in, it started smoking, so I sold it to someone who had the knowledge to service it. That wouldn’t just be due to the hot chassis, would it? I don’t think home users had isolation transformers at the time these were in use.

Assume it's going to need capactors if you want it to run reliably, and it will likely quit working fairly soon due to leaking capacitors. Your Predicta likely had a cap that shorted causing the smoke. It has nothing to due with the hot chassis.
Seeing as it's working, make sure the picture's bright becuase picture tubes are getting closer to being unobtainable.


Here's a good book on 50's era TV repair that's well written for the beginner.
https://worldradiohistory.com/BOOKSH...rd-Johnson.pdf

[Electronic M]

I more or less agree with what's been said.

If it's been powered on in the last month a variac isn't going to help.

Pretty much all sets prior to ~64 had paper caps and those are usually all bad... sometimes enough of them are just barely semi-good enough for the set to run a few minutes or hours with them, but they're short fuse time bombs... Lytics often are as bad.

If a sets been on recently may as well raw dog it with wall voltage, if a set hasn't I sometimes bring a variac, always bring a CRT tester and often a test pattern generator when I have reason to be optimistic.

Hot chassis have existed since the 30s and haven't gone away...There are still TVs today with a partial hot chassis. Post-WWII rules got more stringent about not exposing the chassis to the outside of the cabinet so chassis bolts stopped being threaded into the chassis and instead into plastic blocks, knob shafts had to be cold or deeply recessed with a cabinet captive knob, tube shields had to be captive in metal cabinet sets to avoid shorting chassis to cabinet, etc.

Hot chassis aren't a fundamentally bad design, just a cost saving measure. Theres always been hot chassis sets and there's always been transformer sets.

You only need an isolation transformer if you are repairing the set and need to connect AC powered test equipment (It's good for general safety during repair too, but not strictly necessary if you aren't using AC powered test equipment and know how to work safe).

If you want a working tube era set for regular use you basically have to learn how to fix it yourself or be friends with a technician. An unrestored working set probably won't last a month of say 6 hours a week run time, a restored set may last 6 months to 6 years like that, but will need service eventually.

When tube sets were new we had a repair industry in this country for a reason.
That said repair can be a fun and rewarding hobby.