Ge 21c2465

[bandersen]

Originally Posted by wa2ise

Maybe the horizontal blanking isn't working? Hooked up backwards? Does it move in the opposite direction of the motion of the main picture when you play with the horiz hold?

Yes, it does move in the opposite direction

[wa2ise]

A few more thoughts: Looks like the flyback pulse leaking into the video. Could be from the CRT cathode wire being too close to the flyback transformer (This still an on bench test setup, or did you put the chassis in the cabinet?). Maybe the CRT aquadag not grounded? Brightness wire line to the CRT needing a bypass cap? (maybe the wrong size cap or bad connection?). Cover not mounted on the flyback cage (TV set designers relying on the cage to contain the flyback pulse from leaking into other parts of the set?)

[old_coot88]

How solid is the horizontal locking action itself, rock solid or soft and 'drifty' around center? Does the set use tube diodes for hor.AFC or the typical 3-legged SS phasing diode? If the latter, it's a very common failure mode causing weak or absent hor. sync.

[Phil Nelson]

Urk, that almost looks like an acute case of the "fuzzy bar" issue that drove one Predicta owner nearly crazy. There was a long thread about that either here or on ARF sometime in the last couple of years.

Speaking of GEs, isn't this the same model for sale in Providence?

http://providence.craigslist.org/atq/3708999095.html

Phil Nelson

[bandersen]

Originally Posted by wa2ise

A few more thoughts: Looks like the flyback pulse leaking into the video. Could be from the CRT cathode wire being too close to the flyback transformer (This still an on bench test setup, or did you put the chassis in the cabinet?). Maybe the CRT aquadag not grounded? Brightness wire line to the CRT needing a bypass cap? (maybe the wrong size cap or bad connection?). Cover not mounted on the flyback cage (TV set designers relying on the cage to contain the flyback pulse from leaking into other parts of the set?)

You might be on to something. It just occurred to me that this set doesn't have a HV doorknob cap and the test CRT doesn't have any aquadag coating. So when it's on the workbench there's no HV filtering at all.

Originally Posted by old_coot88

How solid is the horizontal locking action itself, rock solid or soft and 'drifty' around center? Does the set use tube diodes for hor.AFC or the typical 3-legged SS phasing diode? If the latter, it's a very common failure mode causing weak or absent hor. sync.

It does have a 3-legged SS diode and I haven't replaced it. The horizontal lock is OK, but not great so maybe I should replace it.

Originally Posted by Phil Nelson

Urk, that almost looks like an acute case of the "fuzzy bar" issue that drove one Predicta owner nearly crazy. There was a long thread about that either here or on ARF sometime in the last couple of years.

Speaking of GEs, isn't this the same model for sale in Providence?

http://providence.craigslist.org/atq/3708999095.html

Phil Nelson

That's close, but not quite the same. The legs go all the way up to the top on my set.

[decojoe67]

I've always passed on sets that have cabinet issues that are beyond simple touch-ups and buffing. Watching that great job you do on serious cabinet issues is giving me confidence to step-up my skills.
That top looks excellent already!
Joe

[bandersen]

Originally Posted by decojoe67

I've always passed on sets that have cabinet issues that are beyond simple touch-ups and buffing. Watching that great job you do on serious cabinet issues is giving me confidence to step-up my skills.
That top looks excellent already!
Joe

Thanks. I think once you get the hang of strippers, grain filler and lacquer, it's really not that hard.

I replaced the dual selenium with a modern dual schottky diode and it made no difference. Neither did moving the CRT leads around so I installed the chassis into the cabinet and hooked up the new CRT.

The issue remains but it's not nearly as bad as it was.


It's hardly noticeable when viewing actual programming.


I need to do a little work on centering the picture and it's still not quite as bright as I think it should be.
There's also a bit of buzzing in the audio that varies with the contrast control. Perhaps an alignment will get rid of it. Otherwise, the sound is great

[Boobtubeman]

Damn good lookin TV as compared to its beginning..

Steve

[Charlie]

Bob, those are some awesome screen shots! I used to try hunting for that cause of the lighter bar on the left side... and eventually would give up since it wouldn't be noticeable while viewing the video.

That set in Providence looks like the one for sale here near me in Kountze. I wanted to go pick the set up this weekend, but having to stay off my feet for a few days following a little surgery. I'm sure it will be there next weekend... I know it's been there several months already. One more weekend wont hurt.

I, too, will be looking for those small knobs.... dammit. Even worse, I will have to look for that name badge in the center of the speaker.

[bandersen]

I think I can help you out a little with some small knobs. I have a few dinged up ones left over.

Another little issue I have is some nasty arcing sounds when the screen first lights up and when the set is turned off. So far I haven't been able to pinpoint the source. It doesn't happen with the little test CRT so I'm thinking it has something to do with the coating on the big CRT. Maybe I got it too close to the yoke or HV anode ?

[old_coot88]

Originally Posted by bandersen

...Another little issue I have is some nasty arcing sounds when the screen first lights up and when the set is turned off. So far I haven't been able to pinpoint the source.

Possibly the static charge on the CRT face(?) With some sets you can hear it when the HV first comes up, and again when the HV goes off (it's a negative-going static charge as the HV drops). But it's more of a benign crackling and would hardy qualify as "nasty".

[bandersen]

No, this is definitely a loud cracking sound as the picture first comes on or fades away. The image on the screen also goes nuts during the sound leading me to think it might be the yoke arcing to the new dag coating.

[old_coot88]

Originally Posted by bandersen

No, this is definitely a loud cracking sound as the picture first comes on or fades away. The image on the screen also goes nuts during the sound leading me to think it might be the yoke arcing to the new dag coating.

Or possibly an "island" of dag that lacks electrical continuity with the grounded "mainland" (?)
since the effect is most pronounced during the charge-up and bleed-down intervals..

[Reece]

I wonder if that lighter vertical bar or lighter left side could be related to a Barkhausen oscillation? It's not the same as the classic view of it, but could it be an oscillation cropping up in the horizontal output? Some cages have a magnet near that tube, or sometimes an ion trap is strapped to the tube, moved around to see if it makes a difference? Or trying different tubes.

[bandersen]

I recall Phil posted a photo of Barkhausen oscillation recently and it appears as a narrow squiggly vertical line. I did try different tubes and it had no effect.

I've also noticed fine tuning does have quite an effect on it as Eric mentioned earlier. I'm going to hold off on fooling with that issue and the buzzy audio until I do an alignment. Between replacing so many caps, resistors and tubes I figure it's got to be off.

Here's about when the arcing sound is worse as power up


and at power down


I get a sense there's built up energy looking for somewhere to go. I'm also starting to wonder if the sound is actually coming from the speakers and not arcing at all.