1980 Sears (Sanyo) 25" Console TV CRT Problem

[Eric H]

I used to install rebuilt color tubes and they would often snap and pop for a while then settle down.

The reason I asked about the CRT connector is that I bought a Philco 19" set back in the 70's, it had a rebuilt tube but every so often it would let out a very loud SNAP, after about a month the CRT started getting soft and the grey scale went off, after two more replacement CRTS it was still popping now and then so I sold it to a TV repair guy.
He found the insulation around the Focus pin had gone bad and was arcing HV to the guns, this killed the tube very quickly because it was like being rejuvenated every night for a month. He fixed that an no more popping.

[tv beta guy]

Originally Posted by Eric H

I used to install rebuilt color tubes and they would often snap and pop for a while then settle down.

The reason I asked about the CRT connector is that I bought a Philco 19" set back in the 70's, it had a rebuilt tube but every so often it would let out a very loud SNAP, after about a month the CRT started getting soft and the grey scale went off, after two more replacement CRTS it was still popping now and then so I sold it to a TV repair guy.
He found the insulation around the Focus pin had gone bad and was arcing HV to the guns, this killed the tube very quickly because it was like being rejuvenated every night for a month. He fixed that an no more popping.

Wow heheh. Definitely don't want to kill this CRT that way. But yeah, CRT connector looks perfect.

But so far, it's not doing that snapping/popping/arcing anymore.

I would have expected it once or twice upon startup (just not as loud as what I experienced) but to keep on doing what it did. heh. I just wanted to be sure that this was indeed the case, and letting it run would clear it up. So far it has.

I'll keep you posted what it does tomorrow. Right now it's working great playing Family Guy.

Even got the cable box remote to work with it. Got Ebay setup for Sears TV remotes in hopes I'll find the one that goes with it (I saw it in the 1979 catalog on another TV: It has the full numeric keypad, volume up/down, and power buttons, and was quite wide.)

[Reece]

Thinking about why new CRTs snap crackle and pop: I wonder if it's because there are minute sharp points here and there inside where HV concentrates, and after a while these get burned off? I don't mean actual needles sticking out but just little bumps in the coating and/or on the tube elements. They act like tall trees for the HV lightning to strike. Got to be some reason why the tube finally settles down.

[Username1]

well, with the service switch on, there should be less current drawn on the tube. I imagine also as the picture gets dark, hv would go up, and the tube would spark again... does the hv go up on dark scenes? Maybe you should tone it down a bit?

[tv beta guy]

Well, after an entire weekend of letting the TV run 8+ hours a day, it is safe to say that the very loud HV snapping completely quit.

This new old stock CRT is really looking amazing. TV is working excellent.

And now, the videos:

http://www.youtube.com/watch?v=Kh5JkryHdA4
Setting the TV up with new CRT and a talk about what happened.

http://www.youtube.com/watch?v=avkV4seKtZs
And the demo of the TV along with the 1984 Sanyo Betacord VCR after restoration.



My next project is one of those futuristic Zenith corner console TVs. Mine is an '81 with the System 3 chassis and Space Zoom. It currently isn't working. Just blows the B+ fuse. May be a shorted HOT or diode.

What is odd is both that corner Zenith and that 1980 Sears both had casters mounted on the bottom of them (scored them both out of this appliance recycling place).

[tv beta guy]

Originally Posted by Reece

Thinking about why new CRTs snap crackle and pop: I wonder if it's because there are minute sharp points here and there inside where HV concentrates, and after a while these get burned off? I don't mean actual needles sticking out but just little bumps in the coating and/or on the tube elements. They act like tall trees for the HV lightning to strike. Got to be some reason why the tube finally settles down.

I remember reading about that once before, and that makes perfect sense. The TV quit doing the loud snapping while interrupting the picture now, and no apparent damage was done when it did snap. Probably had a big enough imperfection in it to cause what I experienced.

[tv beta guy]

Originally Posted by Username1

well, with the service switch on, there should be less current drawn on the tube. I imagine also as the picture gets dark, hv would go up, and the tube would spark again... does the hv go up on dark scenes? Maybe you should tone it down a bit?

I tested the HV with the brightness/contrast at minimum, and it was a very steady 29KV, which is what the tube was rated for (29-30KV.)

The only adjustment for HV was a 3 position jumper; Normal, High, and Low. It was on the normal pin.

The snapping happened at random, mostly on bright scenes.

[Dude111]

Originally Posted by tv beta guy

Well, after an entire weekend of letting the TV run 8+ hours a day, it is safe to say that the very loud HV snapping completely quit.

This new old stock CRT is really looking amazing. TV is working excellent.

Well good buddy im glad you have the will to keep whats better GOING

[sampson159]

my xl100 19 inch set from 1973 snaps in humid weather.2-3 loud pops and it is fine for days.it is my garage watcher and get used daily.only when humidity is up around 70 percent.winter weather will be a relief!

[tv beta guy]

Wanted to update this thread. The CRT is still working fine after all this time still.

But in the meantime, I kept observing the TV's little quirks, and the audio kept getting weaker and weaker with less bass to the point you had to put it on max with distortion to even hear anything.

So I went all out and recapped the whole TV. Used United Chemicon KMG series electrolytic caps. I found about 6 bad capacitors, two that were completely open, one of which was in the audio circuit. A majority of the smaller value caps were quite marginal on my ESR meter. Only the larger value caps were still good (but I changed them out anyway.)

And now, holy crap does that TV perform now, especially in the audio department. The picture really improved too. So I am quite pleased with the results.

http://www.youtube.com/watch?v=rJYpTz00bFU

This TV should be good to go for a long time now.

And this is one of many future recap projects coming up. As I've mentioned I have about 40+ TVs from 1952 - 1982 that needs restored.

[Eric H]

It seems weird that a Solid State set from the 80's needs recapping but I guess they get old like everything.

I was actually thinking about that the other day when I found a 1981 Hitachi Color Set, I realized that the set was 31 years old now, yet I could remember when sets from that era were brand new.

My first vintage TV was an RCA 8-TS-30 from 1948, I bought it around 1980 give or take a year so at that time it was no older than the Hitachi I just got last weekend, yet it seemed prehistoric at the time, the Hitachi hardly seems old at all to me.

I was 20 in 1980, and now I'm 39.

[Dude111]

Its good seeing him wanting so much to keep her going and not submit to this new garbage that isnt anywhere near as good! -- WE NEED MORE PEOPLE LIKE US IN THIS COUNTRY!!!!!!!! (And the world also)