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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Tue 13, 2016 7:13 pm 
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Methinks you'll find most of your issues resolved with the new thermistor. But just be sure you're getting 4 ohms hot on it or add resistors to make up the difference. I've done a few Barberpoles and Holidays (they're the same. chassis basically) and God they are really voltage sensitive! During the past summer with the AC running and good ol' Met Ed struggling to keep up here in Easton I encountered all sorts of funky little issues in the video that mysteriously self-corrected around Labor Day when the heat broke!

George
Easton PA


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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Wed 14, 2016 1:02 am 
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Location: Coopersburg, PA USA
OK, I installed the new Inrush Current Limiters, and things are much improved - not perfect by any means, but maybe 80% better.

George - when you say make sure I'm getting 4 ohms hot on the Inrush Current Limiters - how can I measure that in circuit? Usually I pull one leg of a resistor to get an accurate reading, but if I do that it won't be hot.

Someone asked that I check out the sync separator tube - 9BR7. Here's what I get:
Pin: voltage spec/voltage actual/Ohms spec/Ohms actual
Pin1: 55VDC/46VDC/40K/34K
Pin2: -2VDC/-16VDC/3.5M/2.4M
Pin3: 0VDC/0VDC/0/0 (Grounded)
Pin4: 24VAC/20VAC/6.5/6.2
Pin5: 24VAC/20VAC/6.5/6.1
Pin6: 0VDC/0VDC/0/0 (Grounded)
Pin7: -.5VDC/4.7VDC/830K/820K
Pin8: 3.5VDC/5.2VDC/150K/150K
Pin9: 19VAC/16VAC/5/5

Looks like resistance is low on Pin2.
Looks like voltage is whacked out on Pin7. Should be -.5VDC, measures +4.7VDC
Will start looking deeper.
Thoughts?

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Stan Saeger
Coopersburg, PA
http://www.saegerradio.com/


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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Sun 25, 2016 12:37 pm 
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Location: Coopersburg, PA USA
Now I have a bigger problem, but I got to believe its simple.

I took the time to clean all of the tube sockets, and now I get nothing at all on the CRT. I looked closely to see if a wire got disconnected while handling the chassis and don't see anything. All tubes are lit and set is pulling correct amps per Sams. Wiggling all tubes doesn't help. I'm beginning to suspect the 1B3 because if I put an insulated screwdriver near the top cap, I get no arc. Shouldn't I draw an arc?

Nothing looks amiss as far as connections to 1B3 and I subbed in another 1B3 with no affect. Can't tell if it is glowing but understand at 1 volt filament, it won't show a glow even in the dark.

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Stan Saeger
Coopersburg, PA
http://www.saegerradio.com/


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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Sun 25, 2016 6:12 pm 
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It sounds like your horizontal circuits have stopped working. You should be able to get an arc on the lead going to the 1B3 even without a 1B3 installed. Is there a fuse somewhere that you could have bumped loose?

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Tom


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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Mon 26, 2016 6:02 pm 
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Tom - Continuing to investigate. No fuses in this set.

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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Wed 28, 2016 1:33 am 
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Still stumped by the behavior of this Predicta. Again, the symptom is no picture or raster at all. Have good audio.

I keep going back to the 1B3 HV rectifier. I get no arc or buzz or anything when I put an insulated screwdriver near or even on the top cap of the 1B3 nor the wire that connects to the top cap.

Would this provide a clue as to why I have no picture at all?

I know that checking voltages of the 1B3 with a meter is not wise due to the high voltages present

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Stan Saeger
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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Dec Wed 28, 2016 2:35 am 
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Joined: Aug Thu 20, 2015 3:09 pm
Posts: 489
Location: Albion, CA, USA
Well, technically there is the fuseistor. I replaced mine with a fuse and resistor combo. But that would kill the audio too. Have you checked the B+ voltages? I don't have a schematic here but have you checked the voltages to the 1B3? Not the HV output but the voltages of the power into the tube. Did you try drawing an arc from the HV output of the flyback?

Also, have you closely inspected the tube sockets? These are known to break and the flaw can be hard to see. The fact that you were playing with the tube sockets just before it quit would make me want to look at them all with a magnifier.


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 Post subject: Re: Predicta Barber Pole Redux
PostPosted: Jan Mon 09, 2017 10:56 pm 
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Location: Coopersburg, PA USA
Well, it turned out to be something simple. I was wiggling each tube, as I had done many times before, but this time I was more aggressive. When I got to the 6CG7 Horiz Multiplier, suddenly got raster. A gentle bend of each pin on the 6CG7 permanently fixed problem.

Now back to getting the picture improved.

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Stan Saeger
Coopersburg, PA
http://www.saegerradio.com/


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