Quote:
Originally Posted by Phil Nelson
I dug out my little old dime-store analog meter and it pegged the needle in the 250ma scale, so I guess the current is higher than the 100-140ma given in the schematic (assuming that this 25-year old Radio Shack special is accurate)...
When I began unsoldering the cathode lead, the terminal instantly snapped off. ... The pin socket is like a bent strip of tinfoil with holes -- not very practical to repair. .... Meanwhile, the TV plays fine with a cathode lead soldered directly to the HOT pin, so I'm tempted to pretend that I never saw those oddball sockets.
Leaving the old fly in place is sounding better. Instead of looking for more trouble, I'll play the set for another long spell today and see how it holds up.
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Vertical linearity still needs improvement, but that's about all I've got left to fret over.
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It's ugly and crude, but it worked. However, it would bother me too. If you can get to those sockets easily, I see what looks like the metal of the pin and terminal metal in the rectangular slot halfway between the actual pin socket hole and where the terminal sticks out. Using a smaller soldering iron tip, you might be able to melt some solder to one side of the metal I see exposed in that rectangular slot, and if you can, connect that cathode lead to that point. Slightly less ugly.
Or as you said, just pretend it's not ugly.
And I'd just tag and leave the new flyback on the shelf, so you can break it out if the old one does die. Not borrow trouble.
Oh, you could test your rat shack meter with a resistor and a source of DC (ohms law) to see what 120ma looks like on it. Though it's not DC on a cathode lead on a HOT. As mentioned above, use the 0.1uf bypass cap on that cathode, close to the tube.
Back in the 70's I was in college (Syracuse University class of 78) and in a EE lab we built and played with el cheapo kit Radio Shack meters. One of the exercises was to show how the AC measurements were done by the meter, and that its circuit assumed sine waves only. Give it a square wave and the indication would be wrong. Found it recently, but the plastic became all crumbly, on the plastic knob shaft. Useless except as a souvenir of college days. With a sticker from a box of Raisin Bran at the time with the Sun logo saying that it belongs to WA2ISE.
As for vertical linearity, you probably already replaced all the paper caps, so check the resistors. Dirt on the circuit board might cause some leakage.