1966 GE PortaColor Restoration - Videokarma.org TV - Video

Dubis7 · #1 10-28-2019, 04:11 PM

Hi all,

I'm in the midst of restoring a 1966 GE Portacolor and was hoping for some guidance. In replacing one of the can capacitors, I screwed up and installed one of the sections backwards. Now it's gone from mostly working to lighting the tube heaters and doing nothing else.

According to the schematic, there's a .5V fuse just before the capacitor I installed backwards. That would trip if someone did what I did, and would cause the symptoms I've seen. I see it on the tube chart, I see it listed multiple times in the schematic, but I'll be damned if I can see it in the set.

I'm including the schematic. Has anyone worked on one of these before? I'm trying to find fuse M2. Am I losing my mind or something?

https://drive.google.com/file/d/1q4d...ew?usp=sharing

maxhifi · #2 10-28-2019, 04:18 PM

Quote:

Originally Posted by Dubis7

Hi all,

I'm in the midst of restoring a 1966 GE Portacolor and was hoping for some guidance. In replacing one of the can capacitors, I screwed up and installed one of the sections backwards. Now it's gone from mostly working to lighting the tube heaters and doing nothing else.

According to the schematic, there's a .5V fuse just before the capacitor I installed backwards. That would trip if someone did what I did, and would cause the symptoms I've seen. I see it on the tube chart, I see it listed multiple times in the schematic, but I'll be damned if I can see it in the set.

I'm including the schematic. Has anyone worked on one of these before? I'm trying to find fuse M2. Am I losing my mind or something?

https://drive.google.com/file/d/1q4d...ew?usp=sharing

It is shown on the bottom left hand corner of the "printed circuit - top view" diagram, which is the image on the right hand side of page 8.

Find L34, and trace it out - one wire should go to a rectifier diode, the other to fuse M2.

Also, this may not be a normal glass fuse.. sometimes TV sets (no idea about this one) used a hair thin piece of wire as a fuse. If this is the case, put in a normal AGC fuse holder and install a normal 1/2 amp fuse.

Dubis7 · #3 10-28-2019, 04:27 PM

Quote:

Originally Posted by maxhifi

Also, this may not be a normal glass fuse.. sometimes TV sets (no idea about this one) used a hair thin piece of wire as a fuse. If this is the case, put in a normal AGC fuse holder and install a normal 1/2 amp fuse.

That might be worth checking. I'll see if that's the case here. Thanks.

Dubis7 · #4 10-28-2019, 05:31 PM

Okay, I traced the two ends of L34 and haven't had any luck. Everything has continuity so far. Any other direction?

maxhifi · #5 10-28-2019, 08:13 PM

Quote:

Originally Posted by Dubis7

Okay, I traced the two ends of L34 and haven't had any luck. Everything has continuity so far. Any other direction?

Luck with what? What has continuity? Are you getting B+ when the set is on?

damen · #6 10-28-2019, 08:51 PM

Many times the GE factory literature would dedicate an entire page to "production changes" using a code number generally ink stamped on some large metal part of the chassis,usually 3 digits. Fuses added, fuses removed, resistor/cap values changed. Which section of the cap was mis-wired? (C what?). Will have to back track from that point.

Dubis7 · #7 10-28-2019, 09:10 PM

Quote:

Originally Posted by maxhifi

Luck with what? What has continuity? Are you getting B+ when the set is on?

Sorry, should've been clearer. In tracing the line between L34 and the associated 100uF cap, there are no visible fuses and everything has continuity. All the diodes test good, and I run continuity tests on all the wires to see if one of them was meant to work as a fuse. If they are, then none are broken.

Right now the cord is locked into the back of the cabinet, so I haven't been able to run any tests to see where the B+ breakdown is. I'm going to guess I don't, though, since there's no life beyond the filament string. My next step is going to be freeing that cord so I can start doing voltage checks with the set on.

Dubis7 · #8 10-28-2019, 09:16 PM

Quote:

Originally Posted by damen

Many times the GE factory literature would dedicate an entire page to "production changes" using a code number generally ink stamped on some large metal part of the chassis,usually 3 digits. Fuses added, fuses removed, resistor/cap values changed. Which section of the cap was mis-wired? (C what?). Will have to back track from that point.

You know, I should check that. I know which cap it was and have since corrected the orientation, but since the schematic showed a fuse there I assumed it was C2-B. However, now that you mention that and I'm actually taking a step back, I think it was C2-D. I'm checking for where that is on the schematic now, and I can also check directly on the unit either late tomorrow or Wednesday.

Popester · #9 10-28-2019, 10:18 PM

I was always taught to make diagrams on a piece of paper when changing out a multican capacitor but I suppose in this modern electronic day we all live in a picture taken on a phone is just as good to do too.

dieseljeep · #10 10-29-2019, 09:22 AM

Quote:

Originally Posted by Dubis7

Sorry, should've been clearer. In tracing the line between L34 and the associated 100uF cap, there are no visible fuses and everything has continuity. All the diodes test good, and I run continuity tests on all the wires to see if one of them was meant to work as a fuse. If they are, then none are broken.

Right now the cord is locked into the back of the cabinet, so I haven't been able to run any tests to see where the B+ breakdown is. I'm going to guess I don't, though, since there's no life beyond the filament string. My next step is going to be freeing that cord so I can start doing voltage checks with the set on.

The power cord interlock connector is held by a "C" clip, easy to remove. It's the earlier PortaColor chassis.
IIRC, The set has two power supplies, one half wave 140 volt source and one 240 volt, voltage doubler source. It has three power supply diodes and maybe two wire-wound resistors. The power supply is near the HV enclosure and there should be a fuse nearby, as well.

Sandy G · #11 10-29-2019, 09:26 AM

1966 Porta-Color ?!? Could be a very early example. I THINK they introduced these things in fall '65 for the '66 season. My Dad always said he got the 1st one in NE Tennessee, he loved being the 1st one w/a new toy like that. Also, the rather decrepit Zenith 24" B/W we had FINALLY went Ker-Pop! & died.. The little Porta-Potty took up about a 10th of the room, the old battleaxe did, that wasn't a bad thing, either, & it was COLOR !! Whoo-Pee !

zeno · #12 10-29-2019, 11:16 AM

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 · #13 10-29-2019, 12:36 PM

Quote:

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.

Dubis7 · #14 10-29-2019, 07:21 PM

Okay, so R119 is tested and has continuity. I rechecked the diodes, all appear to behave as expected.

So now I'm looking at the connections around C2 D. It has two wires. One goes to the vertical linearity control, which I checked and it appears to be operating normally. The other goes to the circuit board, and I'm having some trouble finding that on the schematic. Perhaps there's something on the circuit board that's blown?

Still no sign of that fuse. I'm wondering if that wasn't removed on the version I have.

I also plan to pull the power cord tomorrow and do some voltage tests. Maybe that will highlight where the power is failing.

Dubis7 · #15 10-30-2019, 12:14 AM

Okay, hold on.

Can someone double check C1 for me. I think I may have figured out what I did wrong.

When I removed the original C1, I directly wired M1 and a few other pieces that were connected to the negative terminal of C1 to ground, and I also connected the negative terminal of the replacement C1 directly to ground.

However, C1 was mounted through an insulating pad, and in looking at the schematic, that's not actually what's going on with it, is it? Should I rewire it to have it floating away from ground? Maybe that's the origin of this whole thing.