Quote:
Originally Posted by radiotvnut
Over the years, I've had several 13" and 17" BC chassis sets and most of them had a bad flyback. In my area, we have very hot and humid Summers and I think this is why so many flybacks and triplers failed in sets around here. I recall picking up one 17" BC chassis TV off the street and after replacing a bad power switch, it came to life - for about 15 minutes. I was test running it; and, all of a sudden, the picture got darker, fell out of sync, pulled in on the sides, and BAM - the flyback went up in smoke and stunk up my shop. When it went, it also took the HOT, voltage regulator, and both fuses with it.
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Classic solder on the horizontal drive transformer gripe. It'd eat a flyback in an instant. The set heats up, warps the board just so, and boom - no/reduced drive, and the horiz output transistor goes into near or 100% conduction, eating the primary coil on the fly. Overcurrent protection was nil, or a small (fusible) resistor of a half-ohm or so in the B+ to the transistor collector - the fly would go, and the resistor was fine.
It was a must on these sets to resolder (with lead/tin solder) the horizontal drive transformer, the HOT connections, and check the ESR of the caps on the scan derived side - the ripple current would overheat the fly as well...
Funny thing - RCA's 2005-ish M134C chassis had the same problems....seems they never learn....