"JURB6006" wrote in message
...
I ran into this myself a few times. Without the Sencore somehow you need
to
excite the fly. With nothing connected to the anode output, shorting the
black
wire to the normal ABL pin (not sure of the number right now, but it's the
one
with the spark gap) will distort the waveform on a direct view fly, but
not on
a PTV fly.

Doing this on a Sencore, you should get a "bad" indication with the short
in
place. I don't know if it will show up on a normal flyback ring tester. It
would probably have to be excited to the point where it's putting out at
least
600-700 volts to show up for sure. With lower voltages you might get false
negatives on some because of normal tolerances.

Let's put it this way, however you excite it, if there is any + voltage on
the
black wire it is probaly the wrong part. You should have a negative
voltage
there if anything.


Oh, I forgot to mention,, not having a fly ringer, I simply used my trusty
old ancient (relic from the past) vacuum tube 350V bench supply.

Reasoning that, with a certain amount of voltage, the diodes in the
HV secondary should forward conduct in one direction.

The simple test here is that the flyback for the PTV should not have any
forward conduction to any one of the pins on the bottom of the flyback,
whereas the flyback for the "direct tv" would.

Anyway, I was able to verify that my new flyback was indeed as
intended for a PTV, as I had no forward or reverse conduction
to any pins on the bottom of the fly,, only conduction to the black
wire (as it should be for a PTV fly)

Interestingly enough, I didn't get any forward conduction until
close to 100 volts. So, if anyone wants to try this then, be advised
that you may need a voltage source of 120 volts or more.

Also be advised to use a current limiting resistor as you don't want to
fry the diodes in the flyback HV winding. I played it safe and used
47K

I imagine that one could fabricate a 160 volt source by
simply rectifying the AC line with a diode and capacitor.
( Bearing in mind to be careful with this unless you also
use an isolation transformer)

In fact, I suppose that if one wanted to, they could simply
rectify the line with the diodes in the HV winding itself to
feed a 47K load resistor and simply look at the the polarity
of the rectified pulses on the scope
Only, I guess here, again you would need an isolation
transformer to use the scope, unless you used both vertical
channels set to invert and add.

ah! here's an idea for a simple tester, use the aforementioned
setup with an LED in series with it. The LED would have to
be set up to conduct in the same direction as the diodes in
the HV winding of course.
Ok, lets see how this would be, one wire from the wall
AC would go to the cathode of the LED, then the anode
of the LED would hook up to red HV wire from the flyback,
then the other wire from the wall would go to a 6K-10K
resistor and from there to a test probe that you could use
to probe the pins under the fly or the black wire.



However, AKAIK, the black wire would conduct on
either flyback, so the real test would be whether or not there's
conduction to the pins under the flyback. ( actually the only
two pins in question would be the two that are completely
opposite the side where there are no pins)
Like you, I can't recall which one of these is the one in question,
no biggie to check both though.

A refresher,, conduction ( lighting of the LED) to either of these
two pins would indicate that the flyback is for what you termed
a "direct tv".

If the LED doesn't light up when probing the pins under the fly,
then its a fly for a PTV


Though the black lead would conduct on either flyback,
(PTV or direct tv), perhaps there might be a slightly noticeable
brightnesss difference in the LED that would indicate whether
this lead is being used as a focus lead ("direct tv") or whether
it is the low side of the HV winding ( PTV).

Dunno,, maybe someday I'll build this complicated circuit
and see :-)

=^^= DM