Dumont RA-110 from ETF

[Tom Albrecht]

Is the 1B3 filament glowing?

[Kamakiri]

I'm pretty certain it was, actually.

[kramden66]

i would try the doorknob or doorknobs if it has more then one , that is if your not too buried in the snow, and you do now have a fly tester , simple to use , remove these tubes , the horz out , the hv rect , the damper , one wire goes to the plate cap wire of the horz out and the other to the plate cap wire of the hv rect , before connecting the wires you turn it on , set it to shorts , adjust the needle to the iron core line on the meter , hook wires up to the plate cap wires without touching and you will get your results , the fly will probably sing too.

[Kamakiri]

Flyback was buzzing ever so slightly

Passed the continuity test easy, but the shorts test is not looking so good

And I did disconnect half of the width coil as per the tester instructions.

[Eric H]

Kinda crispy looking too isn't it?

[Kamakiri]

Yeah, kinda

Why is it that sets I fix for other people are easy jobs, and MINE are SUCH a pain in the ass?

[Electronic M]

At least you don't gotta tell folks that X$ of work and caps into it you found some blown part that could be nearly impossible to find...I dread that possibility; which is why I rarely work on other peoples stuff.

[Kamakiri]

And along those lines, neither Stancor nor Thordarson list a flyback for this set.

Welp, looks like I'm gonna pull the picture tube and put it back in the Emerson from which I stole it, and restore that one. I'll stick this one aside until a parts set happens to become available.

[Tim]

Merit lists HVO-90 as the replacement. Possibly one will turn up.

[Penthode]

I haven't seen anyone ask this. I generally test the transformer in service by removing the 1b3 cap and see if I can draw an arc. I would take a pointed screwdriver and connect one end of a clip lead to the screwdriver and the other end to ground. If I can pull a 1/2" to 1" arc, I am satisfied the flyback transformer is okay.

I saved myself looking for a transformer on my old RCA 8TC271. The doorknob capacitor had shorted. I did the same later on my Zenith color TV to find the arc was healthy and the rectifier tube was bad. This was only after I had moved and acquired the spare transformer!

[old_coot88]

Originally Posted by Penthode

I haven't seen anyone ask this. I generally test the transformer in service by removing the 1b3 cap and see if I can draw an arc. I would take a pointed screwdriver and connect one end of a clip lead to the screwdriver and the other end to ground. If I can pull a 1/2" to 1" arc, I am satisfied the flyback transformer is okay.

Wow. Are you serious about connecting it to ground?
The only way i've ever done it or seen it done is to draw an "air arc" with an ungrounded but well insulated screwdriver.
The air arc is just about as long anyway since it's RF. And it doesn't risk overloading the xfmr as a straight-to-ground current path might.

[Penthode]

Originally Posted by old_coot88

Wow. Are you serious about connecting it to ground?
The only way i've ever done it or seen it done is to draw an "air arc" with an ungrounded but well insulated screwdriver.
The air arc is just about as long anyway since it's RF. And it doesn't risk overloading the xfmr as a straight-to-ground current path might.

Yes, I'll ground the screwdriver. I just make sure I do not ground the HV Plate lead.

I just want to ensure the current goes to ground and not through me! One should be able to draw an arc when the tip is about 1/2" away. This is a quick test and should harm the circuit if a tube is used

[old_coot88]

Evidently it doesn't hurt anything. Guess it's just the thought of arcing it straight to ground gives me the willyjeebers.

[kramden66]

Tim
that reading isn't the worst , if you lay the fly tester on its back does it show a different reading ? if the meter went all the way down it would be bad , i've seen good flys read what you are getting , i thought i had a bad fly once because of a reading like that and went through the headache of replacing the fly and it had the same reading , the problem was the doorknob
mike

[Kamakiri]

I test HV with a neon bulb. I was getting HV (although not as much as I'd expect) all the way to the cap of the 1B3, then nothing after. The resistor tests good. Maybe I'll replace the doorknob before I pronounce the flyback dead. Where do I source those, anyway? Or what style do I use? Never replaced a doorknob before.