1966 GE PortaColor Restoration

[old_coot88]

So... is the set now producing a color picture, with proper tint control range?

[Dubis7]

I think so. I at least know all the voltages to the tube match.

I may need to call in someone to verify for me on whether it's "proper" though, since I'm color blind.

How do I tell if the range is proper? Would a video help here?

[old_coot88]

A brief vid would help, showing what the color and tint controls are doing when rotated thru their full range, preferably including a pic containing flesh tone (since flesh tone is center reference for tint range). That brightness problem would be interesting to see also.

[Dubis7]

Okay, here's a showcase of where I am. Sorry for the long video, I was trying to capture everything that came to mind.

Highlights are:

The new video output tube seems to have cured the issues with those bright lines and the signal loss.

I'm noticing some odd behaviors on channel 8 and 9. 9 got better over time, but the static seems dramatically different on 8 from how it appears on the other channels. I showcase that in the video, but that may be normal.

There's a lot of noise in the picture even when I have a stable input signal. It appears to be a sort of cycling movement, scrolling up, and then scrolling to the side. I'll check a few more signal sources to see if that changes depending on the source, but someone else may recognize that issue.

As I already stated, the vertical wobbles when I lower the brightness, and the picture changes size.

There's audio buzz that I'm noticing, but that may also be a signal thing. It's not AC hum.

The color is off. I know the screen needs to be adjusted, but I'm noticing that the colors also seem to be out of alignment and following the cycling movements I mentioned before. I'm not sure if that's an alignment thing or a sign of a problem.

This isn't showcasing flesh tones yet. I'll need to grab a DVD player and set that up. I'll plan to tackle that this weekend. Right now I'm just focusing on picture stability and RF noise. I guess at this point I'm calling the picture "stable" but I feel like it could be better.

Video: https://youtu.be/XHZcKReAZ6A

[old_tv_nut]

I left comments under your video, copied here:

Dark band on channel 2 with no signal - this is probably a slight oscillation coming from the power supply - nothing to worry about, should disappear when you have a normal signal.

Snowy picture with a signal - needs to be diagnosed and fixed. Could be anywhere from a broken antenna wire, or something in the tuner; not likely to be the IF though there is a tiny possibility.

Range of the brightness control with picture completely black may be normal due to sloppy design.

Change of picture size with brightness or fine tuning bringing up stronger image - probably normal. Just make the vertical size a bit bigger to hide the black edges.

Vertical collapse when changing channel - big noise in the signal momentarily kills the vertical - needs to be diagnosed and fixed.

Where you point to color at the bottom, all I see is reflections from the table.

Not sure what the squirmy noise is from, probalby some other nearby equipment? You may have a bad signal connection, as I said above.

The color interference you point at (which I can't see very well) could be an interfering signal of some kind just like the squirmy noise - need to get a good strong noise-free RF connection before going further.

The coarser, stronger interference on channel 8 with no signal is unknown, but again, no use trying to chase something that likely occurs only in a no-signal condition, until you can show that it occurs with a good signal.

In summary, on channels with no signal, you should expect to see snow and hear white noise. You do see snow, so don't worry about it until the strong signal problems are fixed. However, if you don't hear audio white noise, there is something wrong with the sound section.

[Dubis7]

Thanks for the suggestions. So I take it as far as the blurry picture goes, I should start by looking at my signal going from the antenna inputs to the tuner? I know the internal wiring from the inputs to the tuner is right where I was doing a lot of soldering for the filter caps. I wonder if it got damaged. I try some alligator clips across it and see if anything changes, perhaps?

Any thoughts where the "big noise in the signal" might be coming from? Could that be a tuner tube developing an issue? Or maybe a dirty tuner?

I am hearing static audio on the channels with no signal, by the way. I just had it turned down during recording. Beyond the filter hum when I started, I haven't had any audio issues with this.

[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.

[old_tv_nut]

0) Glad you found the broken wire

1) Losing color with fine tuning wrong is normal. Nothing to fix except adjust the fine tuning.

2) Things you point at in still pictures are hard to see in a video due to the coding artifacts on YouTube. Post some still pics here and we will be able to see what you mean much better.

3) Nothing wrong with using the USB player for test material. I have one (I think the same model) and it works fine for me

[old_coot88]

Regarding the buzz, there are two sound coils, the !F and the detector ('quadrature') coil. They're both located right close to the 12BF11. The detector is the one you want to try tweaking first. it's the one located more 'inboard', while the IF is the one out near the corner of the board.

But get the best color picture tuned in first. Then peak the detector for least buzz, and then adjust the IF a bit for best sound. Sometimes you gotta juggle the two a bit.

Sometimes you can minimize buzz with the AGC adjustment too.