1966 GE PortaColor Restoration

[zeno]

There is a resistor shown in series with the fuse. They may have eliminated the fuse & used a fusable resistor instead to save $$. If either are blown
check the 3 rectifiers.

73 Zeno
LFOD !

[Dubis7]

Originally Posted by zeno

There is a resistor shown in series with the fuse. They may have eliminated the fuse & used a fusable resistor instead to save $$. If either are blown
check the 3 rectifiers.

73 Zeno
LFOD !

The rectifiers tested good, but you may be onto something about R119. I'll give that a look the next time I'm at my workbench. It's got some insulation around it, and I wouldn't be surprised if there was something under there.

[jr_tech]

I would first check the three power supplies and the fuse M1 when removed.

jr

[Dubis7]

Okay, so diodes x1-x3 were removed from the circuit, tested fine, and reinstalled. M1 was also removed, checked good, and reinstalled. Still no life.

I'm looking at removing R119 and doing a continuity check across it next. This has to be early in the line.

Where would you all recommend I measure next? I have the cord out of the cabinet and I'm ready to take voltage measurements.

[jr_tech]

Are the 3 power supply (labeled source voltages) in spec?



jr

[Dubis7]

I'm going to assume no on at least one of them. I'll plan to check them either tonight or tomorrow, depending on my schedule. I think I may also take a look at C1 again, just to see if it's got any amps going across it.

[zeno]

Just check for AC ( to GND) on both sides of C1. If there check the
supplies # 1, 2, & 3 for DC.
Keep in mind most the time things in Sams flow left to right.
Try to find a mid point & test voltage. Go upstream or downstream
from there.

73 Zeno
LFOD !

[damen]

RCA used a 3.9 ohm one in a lot of their later sets. The 7 watt part number is 143565, the 10 watt one is 153664. Going up or down 1 ohm should not cause any issues.

[zeno]

I would use the 3.9 ohm. Its there to reduce in rush current at
turn on so the electrolytics charge slower. It also protects the fuse
from random blowing. Most sets do not use a fuse, just the resistor.
In that case it is of a fusable design not just a wirewound resistor.

73 Zeno
LFOD !

[Dubis7]

Originally Posted by zeno

I would use the 3.9 ohm.

Whoops. I bought a 3.5 ohm at 10 watt last night. Oh well. If I decide I'm not happy with it, I can always switch over.

On the plus side, I also decided to add that missing fuse. I'm real sure GE left it out, so I've ordered one and plan to install it where the schematic calls for it. It's probably not necessary, but it will make me feel a little better.

It looks like once that part comes in I'll be able to get back to where I should be. I'll verify it's still passing video and audio and go from there. One more 3 section can to go.

[Dubis7]

Okay, well mixed news.

The new resistor (Replacing R119) fixed the power issue. I now have sound, video, and high voltage back.

Only problem: I've lost part of my vertical deflection. I also was hearing a clicking from the flyback, but I'm still getting HV and that seems to have stopped after I tightened a few screws on the HV cage. Not sure why that would fix it, but there we are.

So here's what I'm going to check:

- I'll verify that I'm getting the correct voltages out of the 3 sections of the
power supply. Perhaps they're too low.

- I'll verify my HV is high enough. Could that cause partial loss of vertical?

I know the yoke is okay, because in fiddling with the height I've been able to get the picture to bounce all the way down, but it almost immediately bounces back up.

I'm including a video as well. Perhaps someone can point me towards a suspect section?

https://youtu.be/D5siDbEAvU0

[jr_tech]

1. good

2. No, If HV is too low the picture would be bigger. (slower moving elections are easier to deflect)

3. Seems reasonable.

4. Have you tried adjusting vertical linearity?

jr

[Dubis7]

Originally Posted by jr_tech

Have you tried adjusting vertical linearity?

I did try this. It definitely reacted, but not enough to fill the screen.

[Dubis7]

A few more clues before I call it a night:

I'm getting a response from the brightness control. When I decrease the brightness, the flyback starts clicking like mad and fills out the screen, somewhat. It more flickers with each click. The picture does grow larger. The picture was shrinking when I increased the brightness before I started.

Also, now the flyback is ringing at me. I'm not sure what that means, or if that makes sense. I took a video of it.

I'm noticing that, when I stick a screwdriver near the flyback ring, small blue sparks jump to it. I think that's normal, but maybe not? Maybe I need to treat the flyback with some corona dope?

I decided to stop taking voltages since I wasn't sure if the ringing was dangerous. I measured two of the three sources, and noticed they were actually running about 10 VDC higher than they were supposed to. I'm not sure if that's within tolerance or not.

https://www.youtube.com/watch?v=A3hx...ature=youtu.be

[jr_tech]

You said in the first post that the tv was “mostly working” before you replaced the electrolytics. So are these new problems, perhaps associated with the rebuilding efforts or were they observed initially?

jr