1966 GE PortaColor Restoration

[Electronic M]

Originally Posted by user181

You would see a 60 cycle component in the waveform. The more pronounced it is, the more ripple is present.

Exact wave shape will vary. (types of rectification and loading applied to it will change it's look). It may also become 120Hz if comming through a voltage doubler.

[jr_tech]

Post #22 in this thread shows a typical ripple for the 270 volt supply. I suspect the other supplies would be similar.

jr

[zeno]

First off IIRC C1 is a 105 deg C & the others are 85 deg C.
Look at the old C1. If you use a lower rated cap it will NOT last
long. The new C1 probably got stressed out when wired wrong &
is the cause of your ripple.
After the ripple is fixed next step is the vert so if you are ordering parts
you may want to order the vert tube. Should be cheap as its
pretty useless for other apps.

73 Zeno
LFOD !

[Dubis7]

C1 has already been swapped out for a new one, but I'll double check the temp rating on the one I used.

I also tried swapping in the vertical tube, no luck there.

I still have not replaced C3, and considering my HV is low and I'm still hearing sparking from around the horizontal section, I'm not sure my problem is originating directly in the vertical section.

I'm going to replace C3 over the next few days and see what changes. Worst case, C3 needs to be replaced anyway. I wonder if that didn't get damaged.

[user181]

Did this issue exist from get-go when you started working on the set, or did it arise at some point later?

[Dubis7]

Originally Posted by user181

Did this issue exist from get-go when you started working on the set, or did it arise at some point later?

There was audio buzz, but I had fixed it. The vertical issue is new since I replaced C2, the brightness didn't disappear at the middle of the control, and I believe the color issue I've noticed now is new.

Here's a video I took. I was able to fiddle a bit more with the fine tuning and get the picture stable. I'm noticing that the picture is actually off the edge of the screen horizontally, which is new (I used this exact computer with the tv before I started) and I'm seeing a line of color where there wasn't one before. https://youtu.be/oYJG5Czpvvo

I'm still waiting on a replacement for C1 to come in. I'm also going to see about swapping in new caps for C2A-C2C, since those could have been stressed when I miswired C1 before.

Any thoughts on where I should go next? Could a lot of these be related to stressed caps on C1 and C2?

[old_coot88]

On the color issue: the chroma signal is getting to the CRT, evidenced by your being able to vary it up and down with the color control. But the 3.58 reference signal appears to be missing (per your vid in post# 82). So apparently GE's (in)famous 'ringing crystal' circuit is not ringing. This could be from loss of the burst signal, bad tube, or possibly a bad crystal.

PortaColor gurus can no doubt pursue the issue further. Maybe somebody could post a full schematic and tube layout diagram.

[user181]

Is DaveWM still active in this forum? He's one of the PortaColor gurus. You might want to send him a DM.

[Dubis7]

Originally Posted by user181

Is DaveWM still active in this forum? He's one of the PortaColor gurus. You might want to send him a DM.

I feel like I've seen him around. I'll see if I can connect with him.

How would I go about checking the ringing crystal circuit? Could that be related to my vertical issue, or am I looking at multiple broken things here?

[Electronic M]

nope, color and vertical are totally separate stages.

[Dubis7]

Originally Posted by Electronic M

nope, color and vertical are totally separate stages.

And here I was thinking it just needed some new filter caps in the beginning. This is turning into a fun puzzle after all.

[user181]

Consider getting a capacitor tester like I mentioned earlier.

[Dubis7]

I have one, actually. A Heathkit C3. I think I need probes for it, though.

I'll take a look. In the meantime, the caps finally came in. I'm gonna swap those in tomorrow. It's been a hectic weekend.

[Dubis7]

Okay, new update video: https://youtu.be/WAhnuri57XQ

I've replaced all the remaining caps from C1 and C2. C1 is now within the correct temperature range, and anything that could have been stressed from previous mistakes in C2 is new.

And actually, the buzzing seems better. So I think that was the right move.

Here's my current remaining issues:

- The vertical is still not hitting the bottom half of the screen.
- That color bar is still visible.

I feel like I should say that I really jumped into the deep end with this one. At this point I'm entirely out of my element. But I don't want to give up!

So basically from this point on, I'm standing by to hear what measurements you would all like to see to move forward. Personally, I'm wondering about the health of the yoke and/or flyback. I say that because my HV is several thousand volts too low, and the yoke could be contributing to my vertical issue. Is there a way to check that?

[Tony V]

As far as the vertical issue, you need to check all the components around the vertical osc. and output tube. A bad cap or out of tolerance resistor in this area would cause the issue you showed us. I doubt very seriously that it's directly a yoke problem.