Plastic ok for mica insulator?

[tommyinajar]

I've installed cap kit  before but this was the first time I had to change a HOT and a V reg.

The fuse was blown and I checked the HOT center to chassis and it was shorted. When I removed it a strip of plastic crumbled and I thought "huh whats this for?"

Short story I checked the new one I installed (before powering up) and it was of course shorted. I just used a thin piece of plastic cut like the one that was on there. That should work temporarily as long as it's not shorted now, correct?

I was asking because the fuse is still blowing. I checked the diodes in circuit D19 - D22 and all the readings are identical- I think they are ok.

Might the Flyback be bad? I can't see any damage on it. It looks original, but I think the board was recapped at some point. Any layman tests ?

 053X0528001 is the right flyback number right? I hate to change it if it's not bad. Trying to save a little $$.

I changed the V reg for the heck of it too- All STR30123 are the same right? it's got 0736 after it and the original has 3625. I was wondering because the pins came bent ( staggered ).

[qrz]

either use a mica insulator w/heatsink compound or the silicone rubber variety.

plastic doesn't exhibit adequate thermal transfer characteristics....

a shorted Hot can take out the Vreg ic.

and shorting the Vreg ic case to gnd can short diodes in the bridge.

[tommyinajar]

I've got a new HOT, Vreg and the c57 Cap. The fuse blew instantly. Well I unplugged the degaussing coil to see if that might be why the fuse was blowing, now the fuse didn't pop but the top of the flyback started to burn and spark. That can't be good. Not sure what to do next, should I spend more money on a new flyback and what about the degaussing coil? Thanks

[MonMotha]

Flyback's toast.  Not uncommon for them to go along with HOTs (often one can cause the other).  If the CRT is still in good shape, there's little reason not to continue attempting repairs.

Degauss coil sounds shorted.  Hit it with a meter on resistance check.  Should be low but non-zero.  You don't need a degauss coil for the monitor to operate, so you can hold off on that until you've got things otherwise working.  You can probably steal one off a trash TV if you want to save some $$$.

[tommyinajar]

I figured after the burning, melting and sparks that the flyback would not be good anymore at the least. I just was wondering if this was "normal" as far as failures, or if I put a new flyback in would that fry too.

In my limited electronic knowledge when you let the smoke out of something, the whole works are usually now shot.

[qrz]

had u checked the bridge rectifier ?
sometimes heavy shorts will take out a diode, or more  .


break this up into sections for troubleshooting .
start with the power supply . look for shorts /opens /leakage.
once satisfied. move on to the h sweep and do same ...
usually, its not terribly difficult to repair this stuff.

[tommyinajar]

You mean D19 - D22? (I've been using the flowchart ) I tested them on the board w/ the diode check they all had the about the same reading, I tested all of them both ways +to+ & +to-(conduct one way, not the other). You can test them with removing them from the board, right?

I've got a new flyback on the way, I'm worried that it will spark and burn like the other one did. Can they fail like that, and there is nothing else wrong except for the flyback?

So far

1:Fuse was blown I checked the hot and it was shorted-

2:Replaced HOT, V-re g and c57

3:Powered up & Fuse blew again

4:New fuse and unplugged degaussing coil.

5: Fuse didn't blow and the flyback started to spark and burn on the top.