My Attempt at Predicta Restoration - Videokarma.org TV - Video

PredictaNoob · #1 05-04-2010, 02:38 AM

If it is OK with the group, I'd like to chronicle my efforts to restore this motel salvage set. I've seen this done here, and quite honestly, the documented steps that others here have bothered to share was the catalyst for my decision to attempt a similar project. This first installment of photos were taken by the guy I bought the set from, so this is how it looked when it arrived at my P.O. Its a 59 Philco Predicta, Debutant model, 10L43 chassis. It was missing the back and power cord, but otherwise complete. It arrived with one small crack to the CRT cover, only visible from the top and won't effect viewing. It smells like hell, if Frank Sinatra were Satan.

PredictaNoob · #2 05-04-2010, 02:47 AM

Here is the chassis before I cleaned it. The whole shebang smells like its been sitting in a giant dirty ashtray for the last 40 years. And as a former smoker, I really, really hate that smell...:

And the ill fitting round speaker someone had installed. I've ordered a proper oblong 4 x 6.

PredictaNoob · #3 05-04-2010, 02:54 AM

Here is the chassis after I cleaned it with q-tips and alcohol (a technique I learned from here!). I tested the resistors and found 20 of them on the board and tuner that were out of tolerance! I've been attacking the rust, but still have a few places to address while I wait on the replacement parts to arrive.

PredictaNoob · #4 05-04-2010, 04:57 AM

Some of the metal parts after rust removal and polishing, but before priming and painting. I used an electrostatic rust removal process to attack the deepest rust spots, using a 6-volt power supply positive terminal connected to a piece of stainless steel, the negative connected to the part (both by-way of cheap alligator clips and some 16 gauge wire. The process pretty much destroys the clips). I used a plastic tub with a solution of salt (1 tbsp per gallon) and let the whole thing soak overnight connected to the power supply. It basically replaces oxidization with ferrous compounds from the stainless steel ~ think Dorian Gray!)

This is pic where I used this process on an old metal/porcelain caster:

Here are the parts:

Sandy G · #5 05-04-2010, 05:59 AM

Wow...I can hardly wait to see more progress...Howzabout the caps ? I'm sure they were a disaster like the resistors were, too...You obviously Know What You're Doing...

PredictaNoob · #6 05-04-2010, 06:10 AM

Here are some of the parts after priming and painting. I used an aluminum-zinc paint trying to come close to the original tone and finish. Its OK, and since no one but me will ever bother looking inside the set, who really cares anyhow?

PredictaNoob · #7 05-04-2010, 06:17 AM

Quote:

Originally Posted by Sandy G

Wow...I can hardly wait to see more progress...Howzabout the caps ? I'm sure they were a disaster like the resistors were, too...You obviously Know What You're Doing...

To be honest, I didn't even bother testing a single one of them. I just ordered the lot from Mouser and will replace all of them.

As for knowing what I am doing? Ha ha!!! Thanks for you kindness, but we'll just have to see what happens next! The only thing I really have going for me is that I am patient and won't rush this. Other than that, I plan to continue to pick you guys' brains for all that its worth! I've been tinkering with radios for 15 years or so, but this is my 1st television. And since most wise people say not to chose a Predicta for your first set, I'm a big enough dumb-sh!t to do exactly that. If it works out, there will be no living with me. If it blows up and maims or kills me, you guys will get a laugh. Either way, it should be entertaining.

Reece · #8 05-04-2010, 06:46 AM

I'm entertained already just following your progress, good show. I've used that electrolytic rust-eater setup before but with "washing soda" (sodium carbonate) available at supermarkets. It really eats the rust off of some nasty cases.

PredictaNoob · #9 05-04-2010, 06:58 AM

Quote:

Originally Posted by Reece

I'm entertained already just following your progress, good show. I've used that electrolytic rust-eater setup before but with "washing soda" (sodium carbonate) available at supermarkets. It really eats the rust off of some nasty cases.

Thanks! Yeah, I tried the washing soda once too, but I really couldn't tell any difference from when I used salt. The salt is "kosher", so maybe that's what makes the difference

I did find that with either agent, you end up with a big ole bowl of yuck. I've been dumping it in my German neighbors flower bed since she continues to let her yappy little dog crap on my front stoop. I watched her looking at her 'rusty' marigolds in dismay yesterday afternoon. What a hoot.

DaveWM · #10 05-04-2010, 07:23 AM

are you planing to pull the main board to get at the bottom side? there are pros and cons

Pros:

allows careful inspection of solder joints and neat replacement of any bad parts, including tube sockets.

Cons:

there are a LOT of wires that are connected to it, and you have to unbend and desolder some big ground stakes.

My approach
On mine I Opted to take the do no harm approach. That is leave it as original as possible, remove as little as possible until I had a chance to evaluate the existing status. I did replace all paper caps and check the can caps. On mine the thin can cap next the the transformer was open. It was a low voltage can 2 section IIRC.

After that I pulled the HOT and did a slow power up with a variac looking for smoke and any signs of distress. checking for voltage drop at the B+ and checking the current.

Next I put in the HOT with an adpater to check the current, power up this time fast and I got raster and checked the current, all good.

then the signal to the tuner and another powr up this this time and its looking pretty good but for the brightness control, an open resistor was the culprit. that is about all it took.

I did have some tube socket issues, the vert out was intermittient, (line on screen, wiggle socket and it comes back) that needed to be replaced.

Also the HV would go away, turned out to be an intermittent damper tube, this time not the socket but a ground stake that completes the filament circuit.

I was able to get replace most of the paper caps with out removing the main board, I used solder braid and low watt iron. On some of the caps that had pads shielded by the chassis I used my solder gun and bent the tip 90 degrees to get at the pad. lots of care and braid to clean it up. Extemly easy to lift a pad this way so you need to go slow and never force a part down.

I was lucky I did not need to replace any other sockets as many are hard to get at and would most likely require pulling the board, but as I said do no harm.

PredictaNoob · #11 05-04-2010, 08:03 AM

Hi Dave,
I've thoroughly read through your restoration thread (several times). Yours was the one that convinced me that this was something I wanted to attempt.
As of now, after corresponding with Sonny "The Radiola Guy", I'm still planning on pulling the board. I am apprehensive (because of the 'cons' you listed), but I'm determined to nug through it.

I can't seem to find solder braid / wick here locally, but I did pick up a very nice German-made solder sucker, it is very long and very slender, about the diameter of a fat writing pen, with a nice long, slender point. It will reach into some pretty tight spaces. And I've got several thin 40W solder irons, as well as a big honkin' antique iron for soldering grounds to chassis, and a good old Weller gun.

I've tested the tubes, and all are OK except for the 6BZ7 on the tuner, which is gassy. Ordered the replacement from ETE tubes.

I am following your advise about powering up via Variac without the HOT, then again with it. I was lucky and learned about "just plug it in and see what happens" on my very 1st antique radio. A nice little inexpensive Admiral that went up in a cloud a acrid black smoke as the transformer turned into a skillet full of molten tar.

I definitely don't want to do any harm, but from the looks of this chassis, it has been the victim of a motel TV repairman's 'gitter-done' attentions, so I'm not taking any chances. I'm just replacing all caps & electrolytics, and touching-up every solder point.

I offer these two pics to support my idea of Motel Joe's hack job:

and this:

I don't know, since I've never seen one, but this CAN'T be a fused resistor, can it?

Since I don't have a television signal generator, I intend to use a VCR for the signal. Is this an OK idea, or worthless?

DaveWM · #12 05-04-2010, 08:29 AM

wow, some one has been re-engineering that one. Not sure what the heck the big sand resistor tack on is for. Yea the fusistor is gone. I have a fusistor in mine, but if it ever goes my plan is to replace it with a 10 ohm power resistor,1/2 amp fast blow fuse and maybe a thermistor to soft the blow on startup.

Hopfully your deflection control pots are ok. I would not mess with them, just hope they are in the right spot. some of them are wirewounds and I had one that was toast, wire busted inside, all cruchy etc.

I do like predictas the module approact make them easy to work on.

PredictaNoob · #13 05-04-2010, 08:42 AM

I ordered a replacement fused resistor, sight unseen, so I'll let you know what I actually get.
As for that sand resistor, its grounded to the corner lug on the board and hooked to the Vert LIN post. Two 10W 2K resistors in parallel. I can't even imagine.

DaveWM · #14 05-04-2010, 09:45 AM

ah, prob replaced the aforementioned wire pot with one that did not have a built in internal stop that limits the throw of the pot. the orig pot is like buzz pot with a built in stop that limits the travel and maintains a min resistance for the cathode to ground which sets the tube bias.

DaveWM · #15 05-04-2010, 09:47 AM

Quote:

Originally Posted by PredictaNoob

Here is the chassis after I cleaned it with q-tips and alcohol (a technique I learned from here!). I tested the resistors and found 20 of them on the board and tuner that were out of tolerance! I've been attacking the rust, but still have a few places to address while I wait on the replacement parts to arrive.

something about that pot on the extrerm right does not look right, Although the mounting arangement seems correct for the type of pot used. Odd. just a guess but the resistor is prob a higher than called for value and the pot is lower than called for. that way less voltage drop across the pot so a lower wattage pot would work (but the range would suffer as well so the fixed resistor would have to be pretty close to the correct total required value).