Are these things I should consider bad

[andy]

...

[TinCanAlley]

Originally Posted by andy

It's not unusual for the ground wire to act like an antenna and pick up signals from things like the flyback and yoke. It looks to me like you have ringing on all of those signals and voltages. It could be a filtering problem, but I think the ringing itself is the problem.

What voltages to you have on the 240v and 750v boost sources? If one of those is low, it could explain the lack of a bright service line, and be causing the bars.

These types of problems can be real head scratchers and often end up being the last thing you would suspect. It could even be the yoke or flyback. You might want to look for a parts donor in an ugly cabinet. A whole chassis transplant isn't a crazy idea if you value your time.

Those voltages test out as 248VDC and 761VDC. So their not on the low side.

I was hoping someone could look over the schematics I posted earlier and tell me what happens when the setup switch is activated. To me, a beginner, it looks like it does something and collapses the vertical. That's my best guess based on what I get looking over the schematics. If that's what's happening, then the lack of setup line for all but a faint blue is puzzling.

If it comes down to replacing the FB or yoke, I'll live with the bars. I don't want to get that involved. I think for the heck of it I'll look over all the caps and resistors in the 750V boost area. Could be a decoupling cap.

[zeno]

Originally Posted by TinCanAlley

Those voltages test out as 248VDC and 761VDC. So their not on the low side.

I was hoping someone could look over the schematics I posted earlier and tell me what happens when the setup switch is activated. To me, a beginner, it looks like it does something and collapses the vertical. That's my best guess based on what I get looking over the schematics. If that's what's happening, then the lack of setup line for all but a faint blue is puzzling.

If it comes down to replacing the FB or yoke, I'll live with the bars. I don't want to get that involved. I think for the heck of it I'll look over all the caps and resistors in the 750V boost area. Could be a decoupling cap.

Service switch kills vertical also kills video & gives the 3 video outs a
constant voltage. On this chassis it also adds a crude blanking pulse.
If all the DC voltages are correct you should get very bright service
lines. At that point its 99% the CRT. Sometimes the CRT can look
& test good but be a little weak.
Good news ! Since I was a bench man & only did about 25 of these
sets I ran it by our old road man over a beer. He did a repair on
one once & it had the exact same jailbars. Bad news is the set was
very old & they didnt want to pay to pull the chassis. At least you
know this wasnt self induced & a real failure, possably common.
Just for kicks remove the wire from service switch that go to
jcn of R295 & R297. See if they go away.

73 Zeno

[DaveWM]

you thinking a leaky switch Zeno?

[zeno]

Originally Posted by DaveWM

you thinking a leaky switch Zeno?

A long shot but yes. When in service instead of video they tie in
a pulse from the FBT. Zeniths had problems with the tiny
remote/man SW & on/off buttons on this vintage getting leaky
& causing random on/off. Rare but they can get leaky & its
gonna be something strange if ever found.

I wonder if anyone here is on the old Electronix pay site ? I bet
the answers there..........

73 Zeno

[TinCanAlley]

Originally Posted by zeno

Service switch kills vertical also kills video & gives the 3 video outs a
constant voltage. On this chassis it also adds a crude blanking pulse.
If all the DC voltages are correct you should get very bright service
lines. At that point its 99% the CRT. Sometimes the CRT can look
& test good but be a little weak.
Good news ! Since I was a bench man & only did about 25 of these
sets I ran it by our old road man over a beer. He did a repair on
one once & it had the exact same jailbars. Bad news is the set was
very old & they didnt want to pay to pull the chassis. At least you
know this wasnt self induced & a real failure, possably common.
Just for kicks remove the wire from service switch that go to
jcn of R295 & R297. See if they go away.

73 Zeno

Okay, Sunday is the day to disconnect the wire from the junction noted to the switch. So I am to leave it in normal mode without that lead in order to see if the switch has a bad connection and might be allowing current from that lead from the setup side to the normal side, right?

[TinCanAlley]

Just thought I'd post a pic of the switch. I don't know if this could cause any problems, but it looks like terminal two of the setup side of the switch is wired to ground, but also the T2 of the AGC pot is also connected to the same terminal on the setup switch. I've circled the ground side in yellow and the power side in red (the lead to be disconnected on Sunday).

[zeno]

Originally Posted by TinCanAlley

Just thought I'd post a pic of the switch. I don't know if this could cause any problems, but it looks like terminal two of the setup side of the switch is wired to ground, but also the T2 of the AGC pot is also connected to the same terminal on the setup switch. I've circled the ground side in yellow and the power side in red (the lead to be disconnected on Sunday).

Its OK they are using it as a tiepoint for ground.
Yes run it in normal for the test.
The CRT dag usually grounds through a few paths. The DGS shield
has fingers on it touching the CRT, usually a spring mounted wire
across the bell under the shield, sometimes the ground straps
touch the dag. Then usually straps run from the shield to the
chassis, tuner assy, & convergence assy. If it were floating you
should hear hissing, used to happen to B&W's sometimes.

Lead dress keeps me worried here also. Be sure the CRT harness
is well away from any HV or large hoz pulses. Focus, yoke,
and the 2 HV leads. IIRC its pretty hard for that to happen on
this set.
Also bad caps may have caused it. Every S cap that opens
brings up everything from the HOT on up 10%. In the olden days
it usually stressed the divider then the F terminal of CRT
socket arcs. If a bunch of them go it starts tossing lightning
bolts like you read about ! Quite a show........
So over time things may have been under stress.

73 Zeno

[TinCanAlley]

Here are a couple of pics of the CRT and the shroud w/ground leads. You can see the two from the CRT socket and the one that goes from the shroud to the chassis. If you look closely at the left side of the neck you'll see the scratches, but I don't think they went through the coating. They appear more as surface scratches.

As for the setup switch, I'm gong to use some Deoxit on it first to see if it needs a little cleaning. I figure that being in the same position for so many years and the fact it's an open design, it might be dirty/oxidized.

[TinCanAlley]

Originally Posted by zeno

Service switch kills vertical also kills video & gives the 3 video outs a constant voltage. On this chassis it also adds a crude blanking pulse.

So is the horizontal still there when in setup? Reason I ask is that the bars go away.

Also, don't remember if I checked the voltages on the G2s and G1s when in setup mode. Maybe that is a next move.

[DaveWM]

the bars go away cause the vert is collapsed.