1966 GE PortaColor Restoration

[Dubis7]

Also, if L34 is measuring 36 ohms, could that be an issue?

[jr_tech]

Originally Posted by Dubis7

Also, if L34 is measuring 36 ohms, could that be an issue?

No.

Also re-check your C-103 reading, it can’t be 0 volts, if it is wired correctly and supplies are normal (or slightly high).

What does your boost voltage measure?

jr

[Dubis7]

C103 should be measured in VDC, correct?

[Dubis7]

Okay, I think I measured C103 wrong. I was measuring from the ground end of C103 to another ground point, and that was 0 VDC. I measured across C103, and it came out as 152VDC

Boost voltage (from pin 3 of the flyback against ground) is 664VDC

HV is still hoving around 10 V using my high voltage probe. I'm noticing that the image is somewhat dim, and I have to have brightness up above center to see it.

[jr_tech]

In its present condition what does the picture look like? Can you connect it to a signal source and take a picture?

jr

[Dubis7]

Sure. I'll take care of that shortly.

[Dubis7]

Here's a video of the output. Vertical is squished, as expected, but I was able to get everything to lock again.

One thing I noticed, and I mentioned it in the video, is that the picture is moving about like a wave. It reminds me of how a boat moves on the ocean. That's new. No idea what might be causing it, but maybe that's a new clue.

https://www.youtube.com/watch?v=0Dmc...ature=youtu.be

Could any of this be caused by a short in C3? I haven't touched that, and it was technically subjected to reverse polarity when I connected M1 to ground awhile back. I need to replace it anyway, but I was sort of holding off until we got all this figured out, since this happened when I replaced C2.

[Dubis7]

Or, no, maybe not reverse polarity. But it was still incorrectly connected directly to M1. Should I try replacing that and see if that's causing my issue?

[jr_tech]

That “wave” action looks like good old 60 hertz getting into the horizontal circuit. Could be caused by poor power supply filter caps or perhaps a heater to cathode short in one of the tubes. Scope the supplies and see how much 60 hz ripple is on each one.

jr

[Dubis7]

Scope with an oscilloscope, you mean? I have one, but I'll have to figure out how to use it. I'm a little fuzzy on the operational theory. The last time I tried to use one, the scales threw me off.

I have a theory that there's something up with the Horizontal Output tube. Maybe I'm off the mark, but I ordered a replacement. It's cheap, and I don't mind having a spare. I'll see if that changes anything.

I may as well go ahead and see what happens if I replace C3. It needs to be done anyway.

I wonder if I should swap in new parts for C2A - C2C? Could those have been damaged when I grounded M1? I'm not sure from the polarity listed, it looks like M1 is actually okay to connect to the negative terminals, and the voltage ratings should be fine, but I'm open to examining my issues here.

[Electronic M]

You likely know this, but if not it merits saying: The portacolor is a hot-chassis set so to scope it without frying TV and or scope make sure to power the TV and ONLY the TV through an isolation transformer.

[user181]

Another sidebar/general comment. Are you keeping records of what you replaced and the outcome related to each one? It's getting tough to keep up with all the components you've replaced, and I want to make sure you're methodically tracking the cause-and-effect with each replacement/substitution so that you're not metaphorically chasing your tail in all this. Also, I'm pretty sure you are already doing this, but if not, be sure you're replacing one thing at a time (unless something is very, very obvious like a cascading fault that unequivocally fried multiple components).

Lastly, you may want to consider getting one of the relatively-affordable ESR capacitor testers. You can test caps in-circuit, and it could save you the hassle of shotgunning a lot of them (at least for the sake of diagnostics -- it's good practice to replace the electrolytics at this age).

[Dubis7]

Originally Posted by Electronic M

You likely know this, but if not it merits saying: The portacolor is a hot-chassis set so to scope it without frying TV and or scope make sure to power the TV and ONLY the TV through an isolation transformer.

Good reminder. Thankfully I have one.

Does anyone have an image of what AC ripple looks like? I'm not sure what I'm looking for.

[user181]

Originally Posted by Dubis7

Good reminder. Thankfully I have one.



Does anyone have an image of what AC ripple looks like? I'm not sure what I'm looking for.

You would see a 60 cycle component in the waveform. The more pronounced it is, the more ripple is present.

[Electronic M]

Originally Posted by user181

You would see a 60 cycle component in the waveform. The more pronounced it is, the more ripple is present.

Exact wave shape will vary. (types of rectification and loading applied to it will change it's look). It may also become 120Hz if comming through a voltage doubler.