My First Vintage Television

[ggregg]

Originally Posted by leadlike

The only jolt I ever got was from the picture tube itself-it can hold a charge for some time.

True but that jolt came from a capacitor through the HV lead to the picture tube.

[jeyurkon]

Originally Posted by ggregg

True but that jolt came from a capacitor through the HV lead to the picture tube.

You can get jolted by the CRT itself. The CRT forms a capacitor. You can even discharge it and get a shock later because of storage effects in the glass.

See Repair_FAQ.

John

[old_coot88]

Originally Posted by jeyurkon

You can get jolted by the CRT itself. The CRT forms a capacitor. You can even discharge it and get a shock later because of storage effects in the glass.

100% correct.

[ggregg]

Good to know. Had that happen before. Coulda sworn I discharged it. I probably did.

[ChrisW6ATV]

CRTs can self-recharge to some degree. I have discharged them many times, then a few seconds or minutes later, I discharge and get another spark again.

To the original poster: This shock hazard in CRTs only applies to sets that have been recently turned on. Nothing is going to hold a charge weeks (or decades) after it was shut off.

[jeyurkon]

Decades no, weeks yes. My Pioneer RPTV tried to kill me. I figured the first shock discharged it but noooo. Not the first, nor the second, nor the third. I'm slow learner.

[sidbartos]

Thanks for the warnings guys. Can someone point out, from the pictures, where inside the set I should avoid poking at for safety? After the holidays I'm going to replace the failed tube and see where that takes me.

[David Roper]

You'll be much better off learning how to properly discharge the tube so that you don't have to worry about any unpleasant surprises.

[dieseljeep]

The first thing to do when working on any set of this nature, is to equip your work bench with a ground-fault recepticle. They respond in a fraction of a second. I had one on my bench ever since they came out.

[sidbartos]

I've researched how to discharge the tube to safely work on the set but no instructions seem to match my set. All of them say to look for a rubber cap on the tube and push a screwdriver under it with the screwdriver connected to ground. The chassis seems to surround much of the rear of the picture tube so it is hard to find this. Anyone have any experience with these types of sets that can give me some pointers? I was also wondering if there was a safe way to measure voltage from the tube before poking around. I ordered a NOS 19AU4 GTA to replace the dead one.
Sorry for all the questions..I figure I'd rather be safe than sorry
Thanks guys

[Tubejunke]

Even if you discharge the second anode by the book the crt can hold some of the charge and bite you while you are holding it! OOPS! BANG!

[Bill Cahill]

The chassis is considered ground.
I'd discharge it several times, holding screwdriver there several seconds each time.
Bill Cahill

[leadlike]

I've discharged the crt several times, only to have it still bite me a few minutes later. It's not a bad bite, just like a bad static snap if you rubbed your feet on the carpet too long. The worst part about getting shocked is having your hands fly back in response, hurting yourself on whatever you catch them on, or if you're carrying the crt and it snaps at you, causing your to drop the thing.

Typically for restorations, we leave the crt in the cabinet, and pull the chassis out for recapping.

[maxhifi]

Man, there is cheap, and then there is the uninsulated plate cap on that horizontal output tube! I would be quick to change that if it was my TV, and I intended to be spending much time poking around in there. Is that common on 50s sets? If the 807s on my RCA audio amplifiers were similarly equipped, I am sure I would have electrocuted myself several times by now.

[Phil Nelson]

That kind of cap (more of a clip, I guess) is not uncommon in my 1940s TVs, but in those the horizontal output tube is located inside the HV cage, where you have to work a little harder to shock yourself.

Phil Nelson