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 Post subject: Predicta restoration
PostPosted: Oct Sat 26, 2019 5:24 pm 
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Joined: Jun Wed 28, 2017 5:32 pm
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Location: Hampton Roads, VA
Hi all,
Wanted to ask if anyone had any good advice about the predicta boards before I go tackling them this winter. I've got both a Debutante and a Blond Pedestal. I figured I'd do the standard recap, and replace the networks and any resistors that are out of tolerance. I know cooling is sort of an issue, has anyone had a lot of luck with PC fans cooling it?


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 Post subject: Re: Predicta restoration
PostPosted: Oct Sun 27, 2019 11:05 pm 
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Location: Waxahachie Texas
Zsuttle wrote:
Hi all,
Wanted to ask if anyone had any good advice about the predicta boards before I go tackling them this winter. I've got both a Debutante and a Blond Pedestal. I figured I'd do the standard recap, and replace the networks and any resistors that are out of tolerance. I know cooling is sort of an issue, has anyone had a lot of luck with PC fans cooling it?

Why not replace all the carbon resistors while you have the board out rather than just the out of tolerance ones? That way you'll know all the resistors are good for a long time. Resistors are cheap and there are not that many of them.
Yeah, I used some 220V fans on some Danish Moderns. Not really needed for Debs.
Good one on replacing Networks. I do sell replacements at TVrestorerguy.com.

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 Post subject: Re: Predicta restoration
PostPosted: Oct Mon 28, 2019 12:52 am 
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Some of the transformer chassis debutantes had holes in the chassis below the circuit board...those sets are easier to change parts on by keeping all the wires connected...to get access to the solder pads where there are not holes unscrew the board, lift the metal fingers holding the wiring harness down alongside the board and unscrew the vertical output transformer...once you've done that you can lift the board roughly 1-3". If you use a small soldering iron (not a gun or 90W cattle prod iron) then you can change any and every part through the chassis holes without going to the hastle of unwiring and rewiring the board.


Last edited by Electronic Memory on Oct Mon 28, 2019 4:44 pm, edited 1 time in total.

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 Post subject: Re: Predicta restoration
PostPosted: Oct Mon 28, 2019 3:54 pm 
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Joined: Jan Sun 18, 2015 5:01 am
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Location: Waxahachie Texas
I forgot to mention to be sure and ohm out all the coils and transformers on the board. Also make sure that the slugs move too.

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 Post subject: Re: Predicta restoration
PostPosted: Oct Mon 28, 2019 9:08 pm 
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My 17" siesta was a breeze.

My 21" pedestal, not so much: You hear tales of fragile tube sockets, so I sprayed them all with deoxit and left them to soak overnight. Still, one of the tubes was kind of a loose fit, so I had to tighten the holes up. Then lo and behold, after I re-installed the PCB and had reconnected all the leads, I had some dry joints on some of the PCB connector pins and one of the sockets, so I had to remove the board and fix them.

I had also removed the tubes from the IF section (so I didn't break them while I was working on the chassis) and one of them was loose after I had put it back in too.

The vertical and horizontal hold only stabilize after it has been running a while, so I figured I might as well buy almost a full complement of tubes for the PCB. Turns out the replacement tubes were worse than the ones already in there. Every time I took a tube out or put one in I was expecting trouble. Even if I replaced all of the sockets, I would be worrying about cracking other joints - the PCB flexes quite a lot.

I replaced all the resistors on the PCB with ones that had twice the power rating.

I was on the fence about replacing the thermistor, but I ordered replacements just in case. Good job I did, because while I was poking around, one of the leads broke off the old thermistor. Ditto the input diodes, but I figured I might as well replace them while everything was lying around in bits.

The main chassis has quite a few power resistors, including that multi-valued input resistor. I replaced them all. The input resistor was way out of spec.

If you are re-stuffing the filter caps, one of them has the -ve lead connected to the case, but the case should not touch the chassis. If it is original, it should have a cardboard cover. Mine was a replacement....

One of the couplates is in the CRT housing and looks like a capacitor. Took me a while to find that one.

Label all the wires you disconnect. There are a lot. Leave the labels on after you reconnect them until you are double-triple sure you have finished with it.

On the other hand, I didn't touch the IF section or the tuner. I knew they worked anyway. YMMV.

Having put it all back together, I discovered that the vertical linearity pot was essentially broken, so I recommend checking their full range. They are actually quite easy to take apart if you feel so inclined, even though they are double-stacked. Just lever up the tabs with a small screwdriver. The ones I took apart looked like they were carbon pots and were pretty clean inside.

I think that's it!

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 3:00 am 
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Joined: Jun Wed 28, 2017 5:32 pm
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Location: Hampton Roads, VA
Thanks for all of the replies. I haven't dug into the Debutante yet though I plan to start this weekend. I'll keep an update on how it goes. I'll be ordering the networks from Chris after I get it apart and see what chassis I have. I know it's a J3406 model, not entirely sure what variant chassis that contains.(Possibly 10L42/43?) I'll add a computer fan or two to the back to circulate airflow. Should be fairly straightforward. Hopefully won't have to pull the boards, but the current plan is to replace the majority of componenets, so we'll see how that goes. It's currently got a raster, though the bottom half of the screen is compressed. Extremely bright picture tube though. Will keep updated on progress. Currently doing this out of my dorm, and have had to shuttle equipment from the workbench here.


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 2:50 pm 
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judge wrote:
My 17" siesta was a breeze.


I was on the fence about replacing the thermistor, but I ordered replacements just in case. Good job I did, because while I was poking around, one of the leads broke off the old thermistor. Ditto the input diodes, but I figured I might as well replace them while everything was lying around in bits.


I think that's it!


I think you mean fusistor. There was no thermistor in the original design. The fusistor was a 5.6ohm wire wound that was designed to burn open if the set exceeded it's designed power draw.


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 4:31 pm 
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Electronic Memory wrote:
judge wrote:
My 17" siesta was a breeze.


I was on the fence about replacing the thermistor, but I ordered replacements just in case. Good job I did, because while I was poking around, one of the leads broke off the old thermistor. Ditto the input diodes, but I figured I might as well replace them while everything was lying around in bits.


I think that's it!


I think you mean fusistor. There was no thermistor in the original design. The fusistor was a 5.6ohm wire wound that was designed to burn open if the set exceeded it's designed power draw.


No. I meant the thermistor. R76 on Sams. Everything after My 17" siesta was a breeze was about the pedestal...

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 6:12 pm 
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judge wrote:
Electronic Memory wrote:
judge wrote:
My 17" siesta was a breeze.


I was on the fence about replacing the thermistor, but I ordered replacements just in case. Good job I did, because while I was poking around, one of the leads broke off the old thermistor. Ditto the input diodes, but I figured I might as well replace them while everything was lying around in bits.


I think that's it!


I think you mean fusistor. There was no thermistor in the original design. The fusistor was a 5.6ohm wire wound that was designed to burn open if the set exceeded it's designed power draw.


No. I meant the thermistor. R76 on Sams. Everything after My 17" siesta was a breeze was about the pedestal...


Which Sam's?
466 shows R76 as a fixed power resistor and R74 as a fusistor.
http://earlytelevision.org/tv_schematic ... hilco.html


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 7:44 pm 
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Location: Grand Chute, Wisconsin
Electronic Memory wrote:
No. I meant the thermistor. R76 on Sams. Everything after My 17" siesta was a breeze was about the pedestal...


Which Sam's?
466 shows R76 as a fixed power resistor and R74 as a fusistor.
http://earlytelevision.org/tv_schematic ... hilco.html[/quote]

Maybe R63? Where is that on the schematic?


Attachment:
R63.jpg
R63.jpg [ 52.17 KiB | Viewed 989 times ]


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 8:08 pm 
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I don't know which SAMS it is - it came with the TV. Here you go:

Attachment:
IMG_4433.jpg
IMG_4433.jpg [ 350.75 KiB | Viewed 981 times ]

Attachment:
IMG_4432.jpg
IMG_4432.jpg [ 278.19 KiB | Viewed 981 times ]

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 8:15 pm 
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Location: Grand Chute, Wisconsin
judge wrote:
I don't know which SAMS it is - it came with the TV.


That looks like you're using Sams 439-1. http://earlytelevision.org/pdf/philco_g ... _439-1.pdf

.


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 8:17 pm 
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wiscojim wrote:
judge wrote:
I don't know which SAMS it is - it came with the TV.


That looks like you're using Sams 439-1. http://earlytelevision.org/pdf/philco_g ... _439-1.pdf

.

Yes. Just verified with https://www.radiomuseum.org/r/philco_pr ... 42m9l.html too.

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 8:24 pm 
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Interesting you learn something new everyday.


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 9:23 pm 
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Looks like you both were looking at the Princess SAMS. If I click on the link you gave (https://www.radiomuseum.org/r/philco_pr ... 42m9l.html), 466-1 is for the princess. I was talking about the pedestal which shares a chassis with the holiday, which is 439-1.

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 9:26 pm 
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judge wrote:
Looks like you both were looking at the Princess SAMS. If I click on the link you gave (https://www.radiomuseum.org/r/philco_pr ... 42m9l.html), 466-1 is for the princess. I was talking about the pedestal which shares a chassis with the holiday, which is 439-1.

Radio museum charges to view schematics and such so I'm not a member and can't view their stuff...


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 9:32 pm 
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Here's a pic of the 439-1 set.
Dan


Attachments:
042.JPG
042.JPG [ 730.15 KiB | Viewed 967 times ]
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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 9:54 pm 
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Electronic Memory wrote:
judge wrote:
Looks like you both were looking at the Princess SAMS. If I click on the link you gave (https://www.radiomuseum.org/r/philco_pr ... 42m9l.html), 466-1 is for the princess. I was talking about the pedestal which shares a chassis with the holiday, which is 439-1.

Radio museum charges to view schematics and such so I'm not a member and can't view their stuff...


You can see the 439-1 at http://earlytelevision.org/tv_schematic ... hilco.html as well as the 466-1 (which I didn't know until this thread!).

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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 10:31 pm 
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Location: Grand Chute, Wisconsin
judge wrote:
You can see the 439-1 at http://earlytelevision.org/tv_schematic ... hilco.html as well as the 466-1 (which I didn't know until this thread!).


Spread the word. The ETF is a great source for free service folder downloads of the most desirable and popularly collected TV sets.

B&W: http://www.earlytelevision.org/postwar_ ... grams.html

Color: http://www.earlytelevision.org/tv_schem ... color.html

.


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 Post subject: Re: Predicta restoration
PostPosted: Oct Tue 29, 2019 10:35 pm 
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wiscojim wrote:
Which Sam's?
466 shows R76 as a fixed power resistor and R74 as a fusistor.
http://earlytelevision.org/tv_schematic ... hilco.html

Maybe R63? Where is that on the schematic?

Not relevant to the set being discussed, but R63 is in the yoke.

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