1966 GE PortaColor Restoration

[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.