RA-103 Focus Rheostat Search

[Chris K]

Was directed here but it looks like the closest replacement is gone forever!

https://www.surplussales.com/Potenti...sRheost-4.html

Would any of these 1k 25 watt controls work and my only consideration would be shaft length ()?

Thanks folks

[Electronic M]

If you happen to be near Milwaukee I have a Stromberg Carlson TV-12 (rebadged Dumont RA-103 in a IMO more stylish cabinet) for sale for $60 OBO. The focus pot is good but the horizontal deflection died on me so I stuck a necked tube in and have been trying to unload it since yesterday.
https://m.facebook.com/marketplace/i...5736250981706/

[bandersen]

Tell you what. Maybe we can make a three-way deal? I have a beat up TV-12 that does have good deflection and a focus coil. Combined with yours - it would make once nice working set. Chris can have the focus coil.

[Chris K]

Originally Posted by bandersen

Tell you what. Maybe we can make a three-way deal? I have a beat up TV-12 that does have good deflection and a focus coil. Combined with yours - it would make once nice working set. Chris can have the focus coil.

Thanks so much you guys!
Chris

[Chris K]

Since Surplus Sales has a number of 1k 25w rheostats available other than the matching one that's sold out, does anyone see a problem with disconnecting the original, leaving it in place for aesthetic reasons and installing a new one somewhere else on the chassis? The issue with the non-matching but available controls is the shaft depth is very different.

[bandersen]

Someone hid a short shaft control inside this set and put a cap over the hole. Dunno what happened to the original control. I'm OK with it. It's not an adjustment you make very often.

[Electronic M]

If the shaft is too short I would find a another junk control of any kind with a long enough half round shaft rob the shaft off the junk control and either use a 1/4" shaft coupler (they make both straight and flexi kinds) to extend it. If both shafts happen to be a solderable metal (ie not aluminum) you could tin the ends with a 80W+ IRON (guns suck for this) and solder the 2 together...a thin sleeve may be helpful.

I had to do the solder cobble method recently for a 60s 13" color Japanese set Packard Bell imported and rebadged....The color/ on-off-vol pot was a concentric with weird shaft sizes and lengths and the inner and outer shafts had frozen together in a way that couldn't be fixed and made both controls fairly unusable. The inner was 1/4" round knurled with the slot and the outer was the giant size 50s-70s fine tuning knobs used. I found an electrically similar pot with smaller shafts in my stash and soldered extensions on to make it work and did a good enough job you would be hard pressed to tell without taking it apart.

[Chris K]

Cool info Tom and Bob!

I finally found the relay answer I was looking for earlier and it's installed and working properly. Now, I have a short I need to run down. As soon as the relay kicks in, my isolation transformer breaker pops. I'll spend a few hours checking the recap and seeing if in moving things around, I crossed any bare leads. After that, I think I'm back to square one...the schematic and checking components. Bummer!

[pearsonk]

Same problem. Buy Surplus Sales rheostat and just extended shaft
using J&B Weld. [cotton thread soaked in J&B, wrap around splice,
let set up -- cut extension to correct length from junk shaft]. Has worked for on my TV 12 for over a decade.
I even have an extra SS pot as I keep a spare.
pearson

[Chris K]

Found my problem...I think. The vertical sweep output transformer has an open coil on the vertical deflection amp side. The set was only drawing 2 amps when it started to smoke so I better make sure I didn't just cook it by leaving it powered up for 10 seconds with an upstream issue or if it was gone from jump. Black tar was oozing out of it but it didn't look too bad. I have another one from a parts chassis but I don't want to cook that one too.