Posts: 60
Threads: 7
Joined: Feb 2018
City: paramus, nj
Hi Guys, I had a question I was hoping you could answer. I have a Predicta Princess with the 10L43 chassis. I bought this Tv from an 70 year old collector of everything and the story he told me was he found it on the curb in roughly 1974, he used it for a while even watched the bicentennial on it, one day he got bored and took the tubes out to clean them and dust the cabinet. He never put it back together because he had gotten a color Tv. When I got the TV he handed me an old Montgomery Ward box with the tubes and the rag still in it. The set looks near mint, I tried to bring it up on my variac but didn't get much of anything out of it. Just a few dimly lit tubes, and no glow from the 2 tubes that are connected to the flyback. Then left it on the shelf waiting for me to finish my tandem. So anyway I was having a bad day and was hoping for some instant gratification, so I went to the local electronics supply and bought all the electrolytic caps to replace all the multi-section caps and the one big cardboard cap. So as of now it has all new filter caps, but everything else is original. I plugged it in and I have no picture, but the heater for the Picture tube lights up, all the tubes have a nice bright glow except for the 2 tubes connected to the fly-back the transformer in the Sam's Photofact labeled T2 is buzzing, and I can hear the same buzz through the speaker, also the tube next to the T2 transformer is getting hotter than the rest. I want to see if I can just fix this set rather than do a full recap. Where should I start to look next. Also I did test the Picture tube with my picture tube tester and it came up very strong.
Posts: 7,212
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City: Roslyn Pa
For those of us who are following from are recliners at home the Sam's for this set can be found here:
https://www.google.com/url?sa=i&rct=j&q=...2764921355 as a pdf file.
< have a nice bright glow except for the 2 tubes connected to the fly-back the transformer
The two tube connected to the flyback are the 1B3 and the 6DQ6. The 1B3 has a small filament and doesn't glow brightly and it's hidden by the plate structure of the tube. To test it measure the resistance at the base of the tube w/it out of it's socket from pin2 to pin 7. Should show a few ohms if open tube is toast. Do likewise with the 6DQ6 measuring pins 2 and 7 I think they are going to be open and in that case you'll need a replacement. Between those two tube they generate the 10,000vdc or so to light the screen of the crt. I would be normal if there is a failure there then the crt screen isn't going to be obliged to light.
> T2 is buzzing,
May or not normal have never had a working Predicta. Can tell you if c-44 is shorted could very likely damage T-2.
> I want to see if I can just fix this set rather than do a full recap.
I have a question for you. How many times would you like to remove the main circuit and it's 30 some odd wires to keep replacing failing caps as they die one by one??
A typical service on these set would include replacement of all foil/paper caps, checking resistor for tolerance and replacing out of spec ones, testing for weak tubes, cleaning the circuit board as they do get very dirty from dust and dirt falling into the vent holes. After that then start the troubleshooting.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 60
Threads: 7
Joined: Feb 2018
City: paramus, nj
That's the thing, this chassis looks so squeaky clean its ridiculous. I guess you could call it an experiment but Id like to see if the set would actually run and how long would it last if I just replaced what had actually failed from sitting. There isnt even any rust on anything, it all looks like it left the factory last night. Just for contrast before I found this one I picked up another princess off ebay and when I pulled the chassis out everything had rust speckles and even some green corrosion in spots. That one I intend to just replace everything I can on because it just looks like its been through the ringer.
I will check the capacitor and tubes you spoke about, is there a way to check T2 also?
Thank You Again
Anthony
Posts: 60
Threads: 7
Joined: Feb 2018
City: paramus, nj
Unfortunately the battery is dead on my meter so I'm going to pick one up tomorrow, but I took out my Heathkit it-22 and hooked that up to the capacitor and something I've never seen before happened. It passed every time saying it wasn't shorted, but when I tested to see if it was open sometimes it would test good other times it wouldn't and then sometimes when I turn the knob the Eye tube would fluctuate back and forth a few times and then all the sudden it would read okay. If I retested it quickly the eye tube would close instantly if I waited at all It would either not close or it would take a while to close. For a control test I hooked up the multi section caps that I removed all of which tested as shorted and I hooked up a couple new ones which all tested good. I have a Heathkit C3 coming in the mail any day now but I'm pretty sure you'll have to take capacitor out to test it right?
Posts: 60
Threads: 7
Joined: Feb 2018
City: paramus, nj
I tried the C3 out tonight and it actually works pretty well. What I've found is non of my filter caps were leaky, however they were out of spec. Some as low as a 3rd of their rating. I tried new caps out and they read almost dead on. C44 isn't shorted but it is leaky. So I'll try changing out next.
