RE: Star Wars - flyback suggestions?

> Er... I still don't nesc buy it. A shorted winding or two on the
> primary
> will be very obvious with a meter, and it may be trickier on the
> secondary....
>
> but a wrap or two on the secondary won't make the flyback unusable...
> and
> if it is a short across (for instance) a significant portion of the
> secondary coil, the resistance will show it.
>
> The only failure mode I can think of that a live test (with a high
> freq.
> signal) might get above and beyond a meter test is a bit of insulation
> in
> the secondary that has broken down (fine under no power, but a high
> voltage arc in the secondary when in operation).
>
(I bet insulation breakdown in the windings is the #1 problem, at least
in GO-7 flybacks...)

The DVM-only technique seemed to work on my WG6100 flyback, so I was
"sure" it would work on GO-7 flybacks too... My test case was about 20
(23?) GO-7 flybacks (done about a year ago-- found a bunch of chassis'
in the trash :-). I used a pretty nice bench meter at home (a Fluke
8000 series) and determined that 4 were definately bad (like blown in
half and leaking "tar"), and the balance were "probably" OK compared to
my brand-new "reference".

I knew this *wasn't* likely, so I took 'em in to work and used the
Sencore's flyback test function. Out of the 19 "probably OK" flybacks I
had 7 that were actually good. The balance-- 12 -- were all dead.
Verified by testing a handful in different chassis until I was convinced
that the Sencore wasn't lying...

As I recall there was a good bit of "difference" from flyback to flyback
compared to the "reference", and with very low resistances to begin with
it was too tough to tell changes of milli-ohms. You might be able to do
it with a VERY accurate ohm-meter, but from my hands-on test the flyback
test/inductor ringer was the only definite way to spot the problem
flybacks...

-Clay
Received on Mon Aug 17 16:50:59 1998