Flyback Failure

[nasadowsk]

I disconnected everything from the 340V supply and hooked an ammeter up at the plate of the 5U4. Turning it up on the variac, I noticed that the *unloaded* power supply was nevertheless drawing about 15 - 20 ma!

Well, that's a good reason why the HV never gets up there with the tv running.

But, here's a weird thing - after letting it sit for a few min...the current started dropping, slowly but steadilly. Is this the 'reforming' effect I keep hearing people talk about? After a while at 340V, the current dropped drastically - down to like 2 - 4 ma. I suspect the lytics are gonners anyway, but this was neat to see in action.

I swapped out a few more caps - the big motherload of 'em comes in tomorrow.

Sucks my current job doesn't do board level, I used to be able to get 40mfd 350 and 400 volt caps at my last one

Looks like the big fun is gonna be replacing the lytics plus the pasper in the sweep sections (a lot are out already, but a few big ones aren't yet).

At least I established that the set isn't totally gone, and that's all I wanted to get at this point. With such an offbeat set like this one, I didn't want to go capping it only to find a dead flyback or yoke, though I guess there are subs out there anyway...

The recieving circuits are on a totally sepperate supply, so I can attack those while I wait for new lytics to come in - that one comes right up into spec, though I didn't check the AC ripple on it.

It's interesting though - one supply for the RF/IF/Video circuits, and another for the sweep. Did anyone else do this back then? It seems like a better idea than lumping everything in one supply...