1966 GE PortaColor Restoration

[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.

[zeno]

The buzz may be from your source. Remember when this was built
there were no add ons like VCR, DVD, games, cable boxes & most
old sets dont like them. AGC & fine tune can affect them also.
The DVD with RF out is the best choice but even at that lettering will drive you nuts with buzz & streaking.

Fine tuning acts like this, I will go clockwise the way most do.
First you get a poor B&W pix & weak sound. As you go CW the
pix & sound get better. A little farther & the color pops in.
If you keep going you start getting a wormy pix then it will go away.
If you keep going you will you usually hit the next channel up.
If a set has AFT, AFC or auto color buttons turn them OFF
before FTing. You dont have them, it "works" without them.

73 Zeno
LFOD !

[Dubis7]

I suppose that's possible. Maybe I can swap in another input source and see if the buzzing changes. It still feels like I should be able to get it better than it is, though.

[old_coot88]

The buzz could possibly be the 'nature of the beast', owing to the highly unusual sound take-off scheme. Both sound and sync are combined in a single triode section of the 11BT11. The actual takeoff point is the plate of the 3rd IF stage, rather than right after the video detector as in conventional designs. It looks like GE's way of going el cheapo and still make it 'work'. It may indeed have worked passably in the days before digital players, digital converter boxes etc.

You might still try subbing the 11BT11 just for the heck of it.

[Dubis7]

I just swapped in a new 11BT11.

I've heard some tubes have manufacturing variances, though. Maybe I'll swap the old one back in and see if the audio changes? The old one had video issues but I could at least figure out if there's a problem with the new one.

[Dubis7]

Okay, so, no luck with the 11BT11. Although swapping back and forth allowed me to double verify that the video lines and flickering were coming from that.

However. My environment has changed since I started on this. Over the weekend I finally got my home tv transmitter started. I've only got two channels up at the moment, but I decided to see what happened using that. Sure enough, it improved the audio home dramatically. So I'm going to call this done for the most part. Here's the set working where I plan to use it. https://youtu.be/s2wph0EkvUg

There's a few odds and ends I'd like to wrap. There's a slat broken off on one of the vents in the back. I'm planning to have a replacement 3D printed. Unless someone has a spare. I'll attach a picture.

I'm also having a few issues with my transmitter. Namely, I'm noticing that any television I have hooked up where my portacolor is (this is only happening in one location at home) experiences vertical loss and bouncing periodically. Nowhere else in the house is that happening, and it's only happening on over the air transmissions.

I may start a new thread for that, but does anyone have any experience with that happening?

[jr_tech]

“ I'm noticing that any television I have hooked up where my portacolor is (this is only happening in one location at home) experiences vertical loss and bouncing periodically. Nowhere else in the house is that happening, and it's only happening on over the air transmissions. “

Sounds like the portapottie is generating a bit if rf interference that is bothering the other tvs... likely in an area of the house with the weakest signal from the modulator.
Might try a snap on ferrite filter on its line cord, it might be helpful to bypass its power supply diodes with high quality caps, 10 nanofarad or so.

jr

[zeno]

First off that set is running very good, about how I remember
one back in the 70's. Well done !

The vert collapse issue is bizarre. Both the vert & horz osc should
be free running at about the right freq without a signal. Only thing
I can imagine is the vert sync pulses from your source arnt right
& the vert is trying to lock way off freq. I do remember a few sets
that "blinked". It was always a bad cap in the vert feedback
( parts running from vert out plate to vert osc grid).

Now that this is wrapped up hows about finding another set for us
to work on

73 Zeno
LFOD !

[Dubis7]

I think I figured out the vertical issue. I was using a different video source when I adjusted the geometry, and as it turns out some of the black and white broadcast shows I'm watching have significant variance in the darkness between shots. I'd already discovered that the vertical on this set can get touchy when the brightness dips suddenly, and apparently it was still doing that. So I played with the vertical linearity a bit more to find a happier balance. That seems to have fixed it.

Just need to get that slat fixed and I'll be done.

Next up is a small adjustment to my RCA 8-PT. I may not need to make a thread on it, but I'll see about posting pictures at least.

[Popester]

You reach a point on these old sets that you have to draw a line in the sand and say. It’s as good as it’s going to be. When I worked at the shop GE was known as generally defective and Portacolor was Porta potty for a reason. That fact that it’s working with a raster, color, and sound is something that should bring you satisfaction. You’re now tuning in a ‘66 year tv with programs that have state of the art tv studio equipment. All those inherent flaws are going to show up. I watch a Sony KV-1920 from ‘75 era and it buzzes whenever a lot of writing or high contrasty picture is displaying. But I’m overjoyed to watch current television on something that is 45 years old. Enjoy it and draw a line in the sand and say I’ve done enough to it.

[Dubis7]

Well, I'm not even gonna make another thread about this one. It took me all of 20 minutes to resolve.

This is a set that was previously restored by Phil Nelson of Phil's Old Radios. I bought his RCA 8-PT, and one of his to-be-restored sets a few years back and finally got a chance to fiddle with it. The Horizontal was struggling to sync, the antenna was damaged, and I wanted to swap the restored chassis into a new cabinet so I could get the legs on it. The paper collar around the ion magnet also needed to be replaced.

That's all done now. I had the antenna cabinet worked on when I picked it up, and getting the broadcaster running inspired me to check out the hoizontal sync. It actually fixed itself once I got the antenna connected. I'm not going to call it "rock solid" in any sense of the word, but I attribute that more to RCA trying to design a cheap set than to any outstanding electrical issues. I may tear into it later and tinker with the yoke a bit. It looks angled, even in the new cabinet, but that's something Phil noted in his original restoration so that could be an outstanding issue.

Perhaps some day I'll tackle the other chassis and reunite it with its original cabinet, but that'll be a future project when I have more experience.

[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.