Philco Predicta pedestal - restoration notes

[ViperZ]

Hi all, long-time member on AK (I guess that's why my registration date is back 14 years ago).. First post...

I picked up my "dream" vintage TV - Philco Predicta pedestal, 9L37 Run 4 chassis. The TV seems to have been barely used, judging by lack of any dust collection inside. The only "modification" was that someone tried to connect an external speaker in series with the existing speaker - I threw out that wire that was sticking out and resoldered speaker wire.

Nothing leaked out, nothing broken. TV powered up, had full bright picture after 30 seconds. I turned it off after a couple of minutes. So now going to remove the chassis for restoration. The plan is to replace capacitors (electrolytic and film/paper), couplets (ordered a kit from tvrestorerguy), and check resistors and tubes (replace as required).

I am planning to order two stacked capacitors from Hayseed Hamfest.

Could someone please confirm values of E1 stacked capacitor? I can see that E2 was bumped from 140uF/150V (service manual) to 150uF/200V (actual cap), which is a good thing in terms of voltage.
E3 matches the manual: 100/200, 10/450 and 200/25.
E1 according to service manual is: 140/300, 100/300, 20/300, 20/300.
300V seems too low, as the voltages indicated on those caps are 275V, so I was wondering if Philco bumped the voltage in the later runs like mine (Run 4). But I cannot see what is printed on the cap body without removing the chassis from the cabinet.

It takes a while for HH to build custom caps, so I want to order the replacement stacked caps before pulling the chassis.

Thank you.

[ViperZ]

Found it... http://www.videokarma.org/showthread.php?t=255328

140/350, 100/300, 20/300, 20/300

[bandersen]

Yes, those are the values they used, but I always add another 50-100 volts for some extra headroom and to increase the lifespan. I also round up the closest standard values made now.

I'd go with this.

150/400, 100/350, 22/350, 22/350

[ViperZ]

Originally Posted by bandersen

Yes, those are the values they used, but I always add another 50-100 volts for some extra headroom and to increase the lifespan. I also round up the closest standard values made now.

I'd go with this.

150/400, 100/350, 22/350, 22/350

Thank you. I'll see what HH will come back with on a quote, but I did ask for for all 400V caps in E1, and bumped up the requested E3 voltage values too. Looks like the highest voltage one is one in a triple 10/450, so bumped that one to 500 too.

[ViperZ]

I checked all functions with my Super Nintendo connected...

It responds to all front controls (brightness/contrast/vertical/horizontal). After a few minutes, it start losing vertical deflection at the bottom.

With Nintendo connected, I can tune in Channel 3 and get great sound, but no picture at all, just noise on the screen. The screen is completely different with Nintendo on or Nintendo off, so it does "something" when Nintendo is turned on.

There are also a couple of black dirt spots on the screen, looks like physical dirt that will need cleaning.

Here is a photo of dark bottom and dirt spots: https://photos.app.goo.gl/1tjHUWYjz6DSTA5S9

I can borrow my parents' VCR for another quick test, but not sure if it is worth doing that.

[Electronic M]

Looks like you have video, but the horizontal is substantially off frequency which is scrambling the picture.

[AlanInSitges]

Yeah you're going to need to pull the safety lens off and clean both it and the CRT. Those things are a bear to get off and, like, six bears to get back on.

[ViperZ]

Thank you both for the input. I was trying to troubleshoot before pulling the chassis, but as Tom C. mentioned, something was off in horizontal circuit. While checking why my vertical deflection was shrinking, I heard a pop and lost horizontal... C11 in horizontal output spilled its guts.
Oh well, now I have no choice, but to pull the chassis.

[Notimetolooz]

Well this is the sort of things that can happen when someone does not follow the common advice to not power up a set as old as this without first at least replacing the electrolytic capacitors.
Some people learn from their mistakes, I hope you do. The damage could have been worse.
It doesn't matter how shiny something is, if it is 60 years old, it is 60 years old.

[ViperZ]

Ok, the chassis is out. While my new couplets are in the mail, and still ordering custom electrolytics, I'll start replacing wax and bumblebee caps on the chassis. I also ordered wrap-unwrap tool, so will wait for it before removing main board from the metal chassis.

[cj_reha]

Originally Posted by Notimetolooz

Well this is the sort of things that can happen when someone does not follow the common advice to not power up a set as old as this without first at least replacing the electrolytic capacitors.
Some people learn from their mistakes, I hope you do. The damage could have been worse.
It doesn't matter how shiny something is, if it is 60 years old, it is 60 years old.

C11 isn't an electrolytic though. It's a .047uF paper cap, which should be changed anyway, but it is my understanding OP is attempting to at least get a picture on the set before completely overhauling it. Predictas are well known to be a challenge to restore and I think it is fair to attempt to get a baseline before going neck deep into unwrapping wire posts, don't you?

[Notimetolooz]

I'm certainly an advocate of doing some testing ahead of time like testing the CRT, however many times people take on their first TV without a CRT tester.

Let's suppose his experience was a bit different. What if he got nothing when he turned it on, completely dead, was he likely to give up and get rid of the TV? I don't think so. He sounds too enthusiastic about it. So what would turning it on accomplish at this point do? He already is committed to restoring the TV. Even if the CRT was a dud, he would go through with it and start hunting for a new CRT.
What it comes down to is he wanted to play with his new toy, even if it meant damaging something.

[ViperZ]

Originally Posted by cj_reha

C11 isn't an electrolytic though. It's a .047uF paper cap, which should be changed anyway, but it is my understanding OP is attempting to at least get a picture on the set before completely overhauling it. Predictas are well known to be a challenge to restore and I think it is fair to attempt to get a baseline before going neck deep into unwrapping wire posts, don't you?

Thank you, that's correct, it is not an electrolytic, and yes, that is exactly what I was trying to do - trying to get a working baseline before going into the complex restoration, in case more problems would get introduced during restoration, which is quite common. I really don't like the fact that main board needs to be pulled, a lot of wires need to be removed, then restorer has to shotgun the board, then put everything back together to run any proper test of TV.

Notimetolooz, I really do not appreciate snarky comments and assumptions about my qualifications, as in both of your responses, which had no useful information so far. Quite a few other people already responded with a lot of help. And yes, I am more than qualified to restore a TV, but was and still am looking for information on restoration of this particular model.

Either way, couplets and vacuum tubes have been ordered. Still talking to HH to finalize multi-section electrolytic order. Then will order whatever I don't have (last big electrolytic and whatever other small parts) from digikey.

[Electronic M]

Of 7 Predictas I have owned I have only once had to completely unwire a board...And I only did it because I wanted to swap a board with one from a parts set.

I haven't worked on a pedistal or holiday yet, but they look like they are probably a striped down Tandem...on my Tandems I figured out if you desolder, the ground lugs, speaker wires from the transformer and a ceramic cap that goes to chassis ground next to the H output the board will lift 1-2" enough to solder the bottom.
https://m.youtube.com/watch?v=1tsFuEi55ZY

The continental and the debutante chassis it's based on have a good number of holes under the board you can work from, and if those aren't enough you can lift the board by desoldering the ground stakes and unscrewing the V out transformer and maybe something else...Been a few years since I did one of those

[judge]

In case you haven't found these resources:

http://www.earlytelevision.org/pdf/p...pair_final.pdf
https://www.earlytelevision.org/pdf/...sams_439-1.pdf (chassis is very similar)
https://www.earlytelevision.org/pdf/...itman_tv16.pdf (ditto)