GE 810 Restoration

[Kevin Kuehn]

I wouldn't suggest putting anything metallic in a microwave.

[Yamamaya42]

Originally Posted by Kevin Kuehn

I wouldn't suggest putting anything metallic in a microwave.

how about microwave plasma using the old grape trick? :p

[Crist Rigott]

I fixed the yoke! I think it was shorting out on the inner tube windings.

I used my heat gun to warm up the inner tube and slid it out of the yoke. This was a mistake. You see the inner tube has some very fine wire windings on it and when I slide the tube out, I broke the fine wire lead that was soldered to the black wire that is grounded to the chassis. You can see it in this photo where the lead is insulated with a small 1/8 long fiberglass sleeve between the 2 layers of windings.




I then continued to disassemble the yoke by separating the 2 windings. They sure liked to used that real sticky cloth tape!

When I removed the aluminum shell I saw that the windings were wrapped with a thin sheet of metal.




The next group of pictures show the disassembled yoke parts.











The next group shows the inner tube and its windings. This is where I think the short occurred. The windings are covered with a very thin plastic type of material. Well there was 1 spot that the windings were worn through and shiny copper colored. You can see this in the picture with the pencil pointing to the worn through spot. The small fine wire that I broke off is at the opposite end of the worn though spot. I peeled back the plastic and unwound about an inch of wire so it can be resoldered back the black wire lug. I then cleaned and added a layer of Kapton tape over the whole thing.








I then made a new insulating washer from an old milk jug. This helps insulate the windings from each other.




I then cleaned and reassembled the yoke. I ohmed it out and sure enough the short was gone. I reinstalled everything and replaced the 5U4G tube. The old tube has little balls of metal rolling around. Fired it back up using my variac checking the current draw. All was fine and I now have my picture back. I'm letting it "burn" in for a while.

[JohnCT]

Nice job.

Reminds me of the mid 90s Mitsubishi projection yokes (essentially B&W) that used to burn from the left horiz winding to the right. Once the yokes went out of production, it was either repair them or lose a repair job.

I used to separate the burned windings and isolate them. Covered with about 10 layers of cyanoacrylate, no more problems.

The good thing is that the burned/shorted area was external, right about where the neck and bell met, so I didn't have to disassemble the whole yoke like you had to.

Impressed.

John

[old_coot88]

Originally Posted by Crist Rigott

I fixed the yoke! I think it was shorting out on the inner tube windings.

Dude. You got more guts than a Army mule.