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-   -   Yet another Predicta Holiday restoration (http://www.videokarma.org/showthread.php?t=261231)

DaveWM 05-13-2014 03:15 PM

another great job Bob. Now on to the Princess!

bandersen 05-31-2014 12:27 AM

Not so fast!

First off, I got a new tripod and better lighting on my workbench :)
https://farm4.staticflickr.com/3750/...118a9880_c.jpg

Next, I wasn't really happy with having the electrolytics scattered around the chassis. So I found an old cap of the proper size, restuffed it and restored the original wiring.

I also added another 10 ohms to the filament dropped to compensate with the higher line voltages encountered today.
https://farm4.staticflickr.com/3775/...87f4e368_c.jpg

I also rebuilt the old dual diode assembly with modern diodes.
https://farm4.staticflickr.com/3725/...fbae873d44.jpg https://farm3.staticflickr.com/2909/...db2437e7a7.jpg

Then the "fun" process of installing the chassis. Remember I was just sent the chassis. The cabinet and CRT are from my set.
https://farm6.staticflickr.com/5536/...befd68c2_c.jpg

It played fine for a few minutes then the horizontal collapsed to a vertical line then disappeared altogether :( The sound is still good though.

I pulled the chassis back out and wiggled some wires. That seemed to fixed the problem at first, but after about 30 seconds it collapsed again. I pulled the chassis twice more with the same result.

So it seems to be an issue with a loose yoke connection or possibly over heating. I'm not so sure about heat though because once the problem occurs, letting the set cool down does not help.
https://farm3.staticflickr.com/2922/...cf6749e0_c.jpg

bandersen 06-05-2014 05:44 PM

It was a pain to pull the set apart again, but I think I found the problem.

When the picture goes out, it collapses to a vertical line then quickly fades away. So I figure it must be an issue with the horizontal circuit.
https://farm3.staticflickr.com/2928/...11321622_z.jpg

Sure enough. A scope confirms that although the hor. oscillator is running just fine, there's no signal on the 12DQ6 HOT grid.

After a little poling around, I discovered that putting slight pressure on the K5 hor, network in just the right spot restores the raster. I figure there's a cracked PCB trace or bad solder joint under that network.

I wedged a bit of foam against the network and the sets has been running fine for a bout 30 minutes now. Next, I'll pull the board out and fix it properly.

https://farm4.staticflickr.com/3899/...fb484866_z.jpg

Phil Nelson 06-05-2014 06:47 PM

Quote:

Originally Posted by bandersen (Post 3106096)
I wedged a bit of foam against the network and the sets has been running fine

When I restored my Siesta, I found the plastic cap from a Bic pen wedged tightly between the main board and the chassis. At the time, I wondered whether it fell there by accident or it was purposely stuck there to "fix" an intermittent connection on the board. The TV worked fine after I redid the board, anyhow.

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

bandersen 06-06-2014 03:14 AM

It helps if you remember to actually solder the leads :sigh:

https://farm4.staticflickr.com/3914/...d257940a_z.jpg

DaveWM 06-06-2014 07:30 AM

I know this already but sometimes forget and then have to "re remember", but I am adding to my check list is a good magnifying glass and strong light, and just go over the pcb/wiring as part of my normal check out.

bandersen 06-06-2014 10:52 AM

I recently added some Xenon under cabinet "puck" lights. They get kinda hot but do kick out a lot of light and they're cheap :)

https://farm6.staticflickr.com/5113/...759771d0_z.jpg

NoPegs 06-06-2014 11:24 AM

Based on his performance of the miracle of healing upon a severely stricken chassis, I believe Bob should be canonized henceforth as Saint Predictia IV. :sing:

bandersen 06-06-2014 09:51 PM

Well I don't know about all that :o I still have several Predictas to restored so we'll see.

I soldered up that open joint and reinstalled the board. The task was made easier because I happened to have another 9L37 chassis nearby for reference.
https://farm4.staticflickr.com/3865/...49b65b48_z.jpg

Viola! It works and has been running for 30 minutes without any more problems popping up :)
https://farm4.staticflickr.com/3900/...f37148fe98.jpg https://farm6.staticflickr.com/5553/...05603edabf.jpg

ed857 06-08-2014 12:41 PM

Bob,
Would you be interested in selling the round bezel + dial glass from your extra RCA 222 cabinet?

I sent you a email.

Thanks

Notimetolooz 06-09-2014 02:33 PM

https://farm6.staticflickr.com/5113/...759771d0_z.jpg[/QUOTE]

That's a nice bench setup, Bob.:thmbsp:

Tim

bandersen 10-16-2014 03:06 PM

I recently received this photo from the owner showing the restored Predicta running in his office :)

https://farm4.staticflickr.com/3949/...3b4b9857_c.jpg

Down Under 10-17-2014 04:21 AM

1 Attachment(s)
Looks great, but I definitely prefer the factory stand.

Kevin Kuehn 10-17-2014 10:40 AM

Hopefully he doesn't leave that test pattern on all the time.


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