CBS Columbia

[timmy]

What would cause a faint white line in the center of the screen at the 12 and 6 position up and down.

[Yamamaya42]

Complete failure of horizontal sweep while still having some HV and vertical sweep is very unusual, but it can happen, but w/o schematic or MO #, who can tell.

CBS Columbia is rather vague.

[timmy]

Originally Posted by Yamamaya42

Complete failure of horizontal sweep while still having some HV and vertical sweep is very unusual, but it can happen, but w/o schematic or MO #, who can tell.

CBS Columbia is rather vague.

I already recapped this set works really nice but between like commercials you can see bearly see the line top to bottom. It has vertical and horizontal produces a nice pic I’m probably not going to worry about it but was wondering.

[Yamamaya42]

Originally Posted by timmy

I already recapped this set works really nice but between like commercials you can see bearly see the line top to bottom. It has vertical and horizontal produces a nice pic I’m probably not going to worry about it but was wondering.

OH that.. is caused by a weak horizontal output tube, most of the time. my Stromberg Carlson BW set did that when cold until I replaced it.

[timmy]

Originally Posted by Yamamaya42

OH that.. is caused by a weak horizontal output tube, most of the time. my Stromberg Carlson BW set did that when cold until I replaced it.

A weak hot even though it’s got a bright picture and perfect hv.

[Yamamaya42]

Originally Posted by timmy

A weak hot even though it’s got a bright picture and perfect hv.

yes, a faint line in the center, a weak horizontal output tube is the first suspect.

[Electronic M]

It could also be a horizontal drive line, caused by an incorrectly set horizontal drive control.

If the line is kinda shimmery like it has white noise in it then it's barkhausen and might be fixed with a well placed magnet on the H output tube.

No picture=guess work diagnosis.

[old_coot88]

Originally Posted by Yamamaya42

yes, a faint line in the center, a weak horizontal output tube is the first suspect.

A 'quick & dirty' test for a borderline HO tube is the "seven seconds off" test. Turn the set off for 7 seconds, then back on. If the width is slow to fill back out, the tube is borderline. Same test will show up other borderline/weak tubes like H oscillator, vert out, color oscillator, RF amp etc.

[zeno]

Originally Posted by Electronic M

It could also be a horizontal drive line, caused by an incorrectly set horizontal drive control.

If the line is kinda shimmery like it has white noise in it then it's barkhausen and might be fixed with a well placed magnet on the H output tube.

No picture=guess work diagnosis.

Yes but if its a true drive line / fold over I would track it down or you may
eat up the H out. Barkhausen & snivets are quite distinctive. Magnet works BUT!
The shop bought out a Radio Shack clone store. They got loaded down
with IEC & Raytheon ( red arrow ) tubes, probably 1000 of them. Cost us 5 cents each. Every H out had problems especially barkhausen. Along
with that there were JA, Euro & one chassis US tubes that were useless.
In the end 5 cents was no bargain !
So bottom line is buy real NOS tubes from real TV makers. Watch out for rest
restuffs, a lot of shops did that. Same with modules. I bet half the
boards on E-bay are duds never returned. The sellers are seldom the
original owners. They are just selling off a clean out & wouldnt know
a dud from a new or rebuilt board. And not GAS.

enuf fer now
73 Zeno
LFOD !

[Penthode]

Adjust the hold control while maintaining sync. If the faint line moves in the opposite direction to the active picture, then the line is due to sync waveform edges being displayed during horizontal retrace.