help with an admiral

[jamie]

first off, i have very little knowledge about working on these sets or tvs in general but i have what i have been told is an 1955 Admiral CA2246. It comes on fine(takes a little while to come on though but i assume that's normal?) I hooked it to my cable with the 75 ohm antenna adapter but get no picture no matter what channel the set is on. I do get sound off what would be the local channels but no cable channel sound. I hooked it up to a vcr as well and still get no picture but do get sound. What should i check for first that causes no picture?

[jamie]

[David Roper]

Any number of component failures can cause a dark screen. There's no point in narrowing it down because the set needs a thorough restoration before you can safely use it. Most of the components under the chassis are probably original to the set i.e. almost 60 years old. Electrolytic capacitors in the power supply can short, possibly causing the smoky failure of a hard-to-replace power transformer. Paper capacitors are leaky electrically, resistors have drifted out of acceptable tolerance. All electrolytic and paper capacitors must be replaced with new ones and all resistors evaluated and replaced as necessary.

But before that, you need to make sure the picture tube is good or at least good enough to be usable. Do you have any experience with electronics? If you don't, you'll want to find somebody nearby who can give you some help as a TV set is not a project for a beginner.

ETA: It is a very nice looking set and it's great that you want to use it. I don't mean to take the wind out of your sails, just want you to understand that doing it right is a major undertaking.

[pugs5061]

Hi Jamie,
David is exactly right. You need to go through the paper and Electrolyte capacitors first. I would find out if your Grampa had a CRT tester also. That is how you find out if the picture tube is good. This test can be done at anytime with or without the chassis in one piece but most people check them before anything else because of the expense of replacing it if it is bad. If you don't have access to a CRT tester they are quite prevalent and not too much $$. Back to the capacitors, at 55 years old, experience has told us that many of them are bad just due to age. The capacitors either leak and go out of tolerance or dry up and go out of tolerance(you can't necessarilly see this). Testing them is really not that realistic because you need to take them out of the circuit to do this. If you are going to take the time to do this why even bother when 1) It would probably take more time than replacing them at that point. 2) Even if they are good they can go bad as soon as voltages hit them. 3) New ones run from 30 cents to $1.00. (not Electrolytes but there are very few of them) 4) If they go bad later it can cause other major components to go bad also costing $$ and making troubleshooting much more difficult.
Keep us up to date! We are saying this to help.

[Phil Nelson]

I agree with all that's been said. Here's a good analogy.

You just found Grandpa's 1955 Chevy in a garage. It drove great when put away and hasn't been touched in decades. Can you just top up the gas tank and drive off on a cross-country trip?

Like this TV, the car has many things that have gone bad from sitting around. The oil in the crankcase is sludge and needs to be drained. The rubber things -- fan belt, radiator hose, tires -- are brittle or cracked from oxidizing and have either fallen apart or will quickly do so when you drive. So on and so forth.

It's a good sign that your TV sort of comes on. But that's like charging the battery and getting your Grandpa's engine to turn over. It tells you that the engine is not completely destroyed. But it's not safe or sensible to drive the thing in this condition.

Perhaps there's someone in your area who can fix it or coach you in learning how to do it. Here's a list of collector clubs. Many radio collectors also collect TVs or know how to fix them:

http://www.antiqueradio.com/clublist.html

There may not be a club next door, but they might know someone closer to you.

Phil Nelson

[AUdubon5425]

There have been a couple of threads posted about evaluating & trying a set for the first time, though I no longer have the links to them.

[Phil Nelson]

He already tried it out and learned about as much as he's likely to discover with no expertise or test equipment. If he plays it any more without at least replacing the power supply electrolytics, he's just asking for trouble.

Phil

[jamie]

Thanks for the advice guys, i will follow all your recommendations. I called grandpa and he does have all the test equipment,boxes of unused tubes, and he said he has a few tube testers. I think hes actually excited to get back into one of these old sets. I'm going to tell him i want to go through everything and hopefully it will be good for the next 50 years. I'm actually very interested to see what lurks in his basement for these old sets..lol.

[wa2ise]

That's a nice looking set. Hope you get it working well. And be sure to put a cover plate on that outlet...

[jamie]

That's a nice looking set. Hope you get it working well. And be sure to put a cover plate on that outlet...[/QUOTE]

I'm hoping it will be an easy restoration once my grandpa gets involved, i just hope my picture tube is good and usable. I'm in the middle of changing all the outlets over to white ones is why the cover was off.

[radiotvnut]

Here are some tips on checking/rejuvenating the CRT.

1. Try to find a fairly new ('70's-on) CRT tester/rejuvenator such as a B&K 467, 470, 480, 490 or a Sencore CR70, etc.). I wouldn't recommend any of the B&K units with a model number below 467 except for testing purposes only. The reason I say this is because the older CRT testers were rather brutal in the rejuvenation department and would often cause more harm than good. The newer testers have a more controlled rejuvenation function that will be less likely to ruin the CRT.

2. Let's assume that you've found a suitable tester and that the CRT test dead or very weak. Don't hit the rejuvenate button just yet. Try raising the filament voltage from the normal 6.3 volts to around 8 volts and let it cook for some time (at least 30 minutes). Then, return the filament voltage back to 6.3 and retest the tube. I've seen some CRT's that would die from sitting unused for decades and cooking them with a higher filament voltage will often bring them back. I wouldn't go any higher than 8 volts, as filament burn-out may result.

C. If cooking the tube fails to work, follow the directions that came with your tester and proceed to rejuvenate the tube. Most testers offer more than one level of rejuvenation and you'll want to start at the lowest level that will get the job done. If you can get the needle to move into the upper end of the "BAD" area or the lower end of the "GOOD" area, hold off on doing anything else for now as you don't want to push your luck and kill what life you have left in the CRT. I've seen many old B&W CRT's that still produced an acceptable picture while testing in the upper "BAD" portion of the scale.

D. If none of this fails to work, you can try a CRT brightener. This is a device that plugs in between the TV's CRT socket and the CRT in order to boost the filament voltage which will increase electron emission. I'm really not a big fan of CRT brighteners and only use them as a last resort. I'll add that I've seen a lot of CRT's with an open filament that had a brightener hanging off of it's neck.

E. If you find that the CRT filament is open (not lighting), there's not much you can do except for resoldering the pins on the neck of the CRT. Fortunately, an open filament is not that common.

When I get an old TV, the first thing I do is check the CRT to make sure that it's either good or it's something that can be brought back to life. No need in going to the time or expense of restoring the chassis if the CRT is shot. If the CRT is shot, you'll have to make a decision on rather to put the set to the side until a good used tube comes along, buy a new tube, or junk the set (which I hope you want do).

[pugs5061]

I think you meant: don't want to do.

[radiotvnut]

Originally Posted by pugs5061

I think you meant: don't want to do.

Yep, that's what I meant. Sorry about that!

[jamie]

Thanks for all those tips. I'll see what grandpa says about the set when he makes it over to take a look. If my crt is bad I will start looking for a good one. I have no plans of trashing the set. You also said i could buy a new crt if mine were bad,are new ones available that will work in my set?

[radiotvnut]

Video Display Corp. is the only place I can think of that might have a new tube; or, you may find an old TV shop or parts house that's been in business forever that still has one sitting back. You could also place an ad in the VK classifieds for a tube.

That TV looks very nice and Admirals from that time period were good performing, well made sets.