1966 GE PortaColor Restoration

[old_tv_nut]

The problem is most likely in the antenna leads, but I suppose the signal from your source could be weak - do you have another good TV to try it on as a quick sanity check?

The "big noise" is normal switching transient when you change channels. Even though the sync separator circuit may see it as a momentary erratic sync signal, it should not cause the vertical to collapse. This would lead me to check components between the sync separator and vertical sweep section, as well as components in the vertical section itself.

Thumbs up on the audio noise!

[Dubis7]

Originally Posted by old_tv_nut

The problem is most likely in the antenna leads, but I suppose the signal from your source could be weak - do you have another good TV to try it on as a quick sanity check?

Yeah, right next to the workbench actually. I'll do that the next time I'm down there.

Originally Posted by old_tv_nut

The "big noise" is normal switching transient when you change channels. Even though the sync separator circuit may see it as a momentary erratic sync signal, it should not cause the vertical to collapse. This would lead me to check components between the sync separator and vertical sweep section, as well as components in the vertical section itself.

That's the 8BU11 again. That's been giving me some strange behavior. I've got a spare coming, I wonder if the tube itself is acting up. I say that because the vertical collapse is a new issue, and that tube only recently started giving me trouble.

[old_coot88]

When you get your DVD player hooked up and ready to display actual color pics, first you need to set the B&W tracking or 'grey scale'. With the color control full Off, and brightness set very low, adjust the Screens so all three extinguish at exactly the same point.

[Dubis7]

Okay, here's a big update post.

Of the problems I listed last time, several are now fixed.

I replaced the 8BU11 tube, which has the sync separator. Sure enough, the vertical is no longer collapsing when I change signals. Picture is much more stable.

I also figured out why there was so much interference in the video. My matching transformer had a broken lead. I swapped a new one and the picture has cleared up.

I had forgotten my DTV converter box can play video from USB, so I went ahead and added a clip to check the colors. I haven't done a full greyscale alignment or anything, but I was able to prove that the color and hue controls work, and get the display pretty close to what I'm looking for. So I'd say my color is working fine now, minus the adjustments I need to make.

There's a few outstanding issues. I've taken a video to show them: https://youtu.be/5xGn8A43S5A

There's a lot of buzz in the audio. I can get it to come through clear enough to understand it, but even with fine tuning the buzz never goes away fully. Is there an adjustment I can try somewhere? Maybe in the audio IF?

I'm also noticing a slight ghosting issue, especially when the images are static. It's almost like there's a second image slightly to the side of the color one. I've read about a delay line issue causing that, but I'm not sure how severe that would look. Alternatively, could it be a convergence problem? I tried to showcase that in the video.

Also, what I didn't show on the video, and I can go back and try to find this, is that when my signal isn't tuned in quite right, I often end up with a good image that's only in black and white. I can reliably get the color image adjusting the tuning. This isn't something that happens regularly, it only happens if the signal isn't tuned in properly. Once I lock it in, it's rock solid. I don't know if that's normal or not, but I figured I'd check.

[Dubis7]

Greyscale adjustment is done. It wasn't far off, but it looks even better now.

I touched up the geometry too. Vertical is much more stable as I adjust brightness. I may do another round later.

I noticed it was a little stretched to the left, though. Does anyone know how to adjust the width?

[zeno]

First off keep in mind what a Portacolor is & isnt. It was built to
sell at $220, later $199. As a rule everything was the cheapest
possible with the lowest parts count. Brand new they "worked"
and thats it. Do not expect perfection from it, GE didnt.
GE stands for "Good Enough" dont you know.....

One thing we found was a PC, especially a first gen like yours after
a few yrs needed a lot of work If we changed one low level tube at a
time you could see improvements with each one. Bad news is
compactrons cost $$ even in 1970. So they were fixed to "work"
again & no more.

Notes
Audio. Put it last. Buzz is detector stage, hiss is audio IF stage.
Vert collapse not normal.
"Blooming" change in pix size probably normal for this set. It is not
highly regulated like in expensive sets.
Tuners have 3 bands. VHF low ( ch 2-6) VHF high ( ch 7-13) &
UHF ( ch 14-83). When the UHF is used 3 things happen.
1) UHF tuner gets power. 2)The VHF osc gets turned off.
3) The RF amp & the mixer in the VHF tuner are turned into two more
stages of IF amps.
So you can get very different performance on different bands with weak tubes. But it can give you clues.
BTW they will usually test good.

IMHO your best next step is to get a good stable source of a color pix
pref a DVD with an RF out.

enuf fer now
73 Zeno
LFOD !

[Dubis7]

I say "width" but on second thought I think horizontal linearity would be what I'm looking for.

Though to be fair, I wouldn't be shocked if there wasn't a way to adjust that. This may be one of those "good enough" things.