1966 GE PortaColor Restoration

[maxhifi]

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]

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]

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

[maxhifi]

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?

[Dubis7]

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.

[dieseljeep]

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.