PTV300 P/S repair

Just in case anyone else out there has one of these relics still working...

I replaced the white flyback with 45 degree HV output (362003-5) with an HR
equivalent for the 362003-7 after looking at the specs for it and the later
362140-1. It looks like pins 1 and 3 were switched between the two styles
and the APW007 P/S board that I have had both sets of locations and sure
enough, those two pins are swapped. I also had to move one of the resistors
to the back of the board since it was physically in the way. Bought five of
these transformers on eBay for $32 total...

So... Put a 150watt light bulb in place of the fuse and turned the power
on. Slight glow from the bulb and the set turned off. Put in the fuse and
turned the set on. Works! One thing that bothers me is that the
troubleshooting manual states that there should be > 100k ohms between TP3
and TP7. With a DMM, I get very strange results. Up until I get to the
high ohms range, I get infinite and then it drops down and increases. From
the schematic, it appears that I'm charging up a capacitor or two. Using
the diode test, I get a basic voltage drop in each direction. Would this be
different with a VOM? I have a dud board and pulled every diode and
transistor in on the B+ circuit. Only by removing the capacitors was I able
to get the >100k reading on my DMM.

What other failures can I expect from this chassis series? I've resoldered
most of the old square thru-board connectors on the p/s, deflection and
convergence boards. Used fresh heatsink compound on the large transistors,
replaced the coolant and converged the set.

If the picture weren't so good, I'd replace it...

Thanks for the help...

Kirk S.


.

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