Flyback Failure

[Don Lindsly]

Lots of wax is a bad sign. Many older flybacks woould drip wax over the years and still operate. I would check for operation as usual. If there is no high voltage, then make sure tubes are good and the tube voltages are close to normal. Remove the damper tube and check for high voltage and a narrow picture.

If you get high voltage with the damper removed, then there is a shorted capacitor from boost to B+. That's easy. If not, make sure there is grid drive and look close to see if the horizontal output tube plate is running slightly red. If so, remove the horizontal yoke wires and see if the boost increases. If so, suspect the yoke.

If not, remove power and feel the flyback down close to the core. If it's hot, 95% chance it's bad. That's a quick troubleshooting technique if you don't have a scope or flyback checker.

There is also a ringing test using a cheap scope and a small cap that has never been wrong for me.

Don