1966 GE PortaColor Restoration

[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 !

[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.

[Dubis7]

As far as picture goes, I'm happy with it at this point. It looks like most of that ghosting went away when I adjusted the greyscale, and I'm thinking that most of that is just the nature of the set. This still has one of those early tubes with much lower resolution.

I'll try adjusting the audio, and if that works I think I'm about ready to declare this set finished, minus a few cabinet cleanups.

[Dubis7]

Played with both coils. Wasn't able to get things much better.

Would it be worth trying a new audio tube? How reliable is the audio diode?

[Dubis7]

I tried to grab a few more pictures of that bleed/shadow image. Hopefully these show up. It's kind of hard to see. There's a dark shadow to the right of each image.

Still playing with the audio buzz, but no luck. I can't get it much better than it already was. I've ordered a new audio detector and output tube to check whether that's causing it, but maybe there's another coil I could adjust? It definitely seems like it's impacted by the video.

[Electronic M]

The sound issue that disappeared when you switched modulators was probably video over modulation....audio is FM and video is AM...AM modulation at 0% is full carrier strength and at 100% modulation is no carrier ( proper AM normally stops just shy of 100% modulation) when AM modulation exceeds 100% the carrier turns back on but is phase inverted 180degrees (or reverse polarity)....that effectively creates phase modulation of the carrier that depends on video and video has a 60Hz rate. Phase modulation and frequency modulation are closely related...any FM modulator creates phase modulation and any phase modulator creates frequency modulation you can switch a transmitter between sending one or the other by applying an integral or derrivative mathematical function to the signal and the Same applies to a reciever just run the output through a circuit to do the math to make is sound correct... that PM noise will make it through the FM detector as easy as a proper FM signal.
Many cheap modulators over modulate the video and use the same carrier for both audio and video resulting in the PM noise being on the sound carrier and having an EASY path through the set.

[Dubis7]

And it's done! Found someone who could 3D print a new slat to get the back fixed. It's not perfect - there's blemishes here and there and the audio buzzes with hot signals - but from what I've heard this is as good as it'll get. I may play with my Agile Modulators and see if I can reduce the signal strength a bit to reduce the buzzing.