DuMont RA-102 vertical transformer bad?

[Phil Nelson]

I haven't had to replace a vertical transformer before, but maybe this will be a first. I'm slogging toward the finish line with a Dumont RA-102 that has an odd (to me) vertical problem which I haven't solved by replacing caps & resistors or swapping tubes.

The TV refuses to lock vertically -- the best I can get is a slow hover. It also shows slanting lines similar to the common retrace lines, but these lines sort of dance along, changing speed & direction as the image hovers upward or downward. Here's a short video:

http://antiqueradio.org/art/DuMontRA...calProblem.mp4

You can download the Riders service manual here:

http://www.earlytelevision.org/pdf/d...102_manual.pdf

The transformer in question is T2, the vertical blocking tube oscillator xfmr:



Checking with an ohmmeter, T2 looks open (infinite resistance) between the Red and Blue primary leads. And the voltage at pin 2 of V16 is zero rather than +180VDC as given in the manual.

Which leads to my real question. Say that this transformer is shot -- what replacement could I use?

The Rider manual lists nothing but a Dumont part number for this item. I see a bunch of blocking osc transformers for sale at Playthings of Past, but they have various ratios and only one of them (STANCOR A-8124) has six leads like this one.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html