[apERNA1985]

I was doing some more testing last night, to tr and find what else is going on. I ran into a little issue, I'm hoping Bob may know the answer considering all the boards he's rebuilt. I have what looks like original resistors on my board but they are different values from what the Photofact says. R67 and R57 they both test good according to the color codes. But they dont match the list. for R67 I have 1.9m and R67 I have 470k. Also according to the Photofact in the bottom of the unit I am supposed to have 2 capacitors that arent there, I dont even see a trace of them, they are C5 and C54. Is it possible I have a later chassis or a later Photofact? What do you guys think?

So far I found that C22 is open, R43 is open, C43 tests higher than its supposed to be at 1.2, R62 is open, C42 is open, R50 only meters out to about 46.5k and has been replaced at least once. Hopefully these are whats causing all my problems. Are they inline with my problems?

[gregb]

You will find that if you want these old sets to work properly you will have to replace all of the capacitors and in my experience at least half of the resistors if not all of them. Then you will most likely have to rebuild the couplates as well. If you watched Bob's videos he goes through all of this and he has had very good results. Once fixed up these are great work TV's and I watch mine all the time.

I have also noticed a couple slight differences between sets I have worked on and the Sams info, I always go with what's found in the set.

Gregb

[apERNA1985]

Gregb I intend to change everything. What I want to do is tac the components that test bad on from the top, then get the TV to function, even if its just a little. Then Ill pull it apart and just repopulate the entire tv. Im worried about introducing problems from 2018 in additon to the problems it has now and then spending months chasing my tail. Watching all the restoration videos on You Tube everyone has some kind of issue on the first power up. So it might be easier to have it sort of working before I take it apart..

[Bob Andersen]

Yes, there were production run changes. The Sams mentions a few in the notes below the parts list, but not all.

Here is the original Philco service manual plus some suplements.
https://drive.google.com/open?id=1FiqZeM...U8HvsOTo0t


I think you have gotten the TV to function. Getting a raster on the screen means all the critical components are OK. You're not likely to get a clear, stable image or sound without replacing the old caps. For example it looks like you are lacking height. That's almost guaranteed to be because of bad (leaky or open) electrolytic caps in the vertical output circuit.

Resistors are typically less of an issue. They can be way off but the set will till work OK. Given the hassle in unmounting the main board, I think it's easiest to just replace all the paper caps at once while you;ve got it out. Also the tube sockets are prone to metal fatigue cracks. Especially the 9 pin ones.

[Radioroslyn]

Hi Bob
Is the source for the 7 and 9pin socket for these old guys?
I've got a Siesta that more than likely will need a few. I
also have some old Heathkit gear the have circuit board
mounted sockets. These are better quality as there molded
rather than the wafer type.But don't know if there's any thing
special abt the predicta ones.

[Bob Andersen]

Nothing special that I know of, but make sure there is a center ground post if the original has one.

I got mine from Surplus Sales of Nebraska.

7P-CP for the 7-pin. Remove the shield if you don't need it. Might be a cheaper source out there. I'm not sure.

751V504C06 for the 9-pin. It's a perfect match with thicker metal used. 28,000 in stock

[TV MAN]

I'm just going to chime in here with a suggestion. Now that you have verified there is life in that set, don't get carried away and try to replace everything at once. I know the Predictas are a little tricky to work on, but I would do one thing at a time - check the set, then go on. If you replace everything at once, and it doesn't work - where do you start? This way, if you do a section, and you have marked improvement, go on, or if you end up with a different problem or its worse, you have an idea where to start looking. I suggest start with the power supply and then move to the vertical section. 2 most troublesome sections. Just my 2 cents. I have one I want to restore too, but too many projects on the bench right now, and a few weeks away from starting my work season.

[Arran]

Except that you really don't have that option with the way the series string Predicta chassis are constructed. Not only do they use printed circuit boards but they are mounted over top of a steel chassis so you can't get at the underside without lifting up the boards. To remove the boards you have to undo a number of grounding stakes, and you will need to unwrap a number of wires from around the perimeter of each board. I'm not suggesting replacing everything in one go, but the way these are built pretty much precludes the technique of replacing a few parts, testing, and then replacing more like you can with a hard wired TV or radio, maybe if you rebuilt one board at a time and then put it back in. The power supply section is built onto the steel part of the chassis, so that is one one the few parts that is hard wired, along with most of the H.V stuff, then you have the IF board, and the sweep board, so you can overhaul that part first. I haven't worked on lots of TVs but I have worked on some earlier AC radios that require a similar restoration approach to this, such as the RCA R7 Nipperete style chassis from 1931-33, and their G.E and Westinghouse siblings, those have potted block condensers, terminal boards, and layered wiring.
Regards
Arran

[TV MAN]

Yeah, I know those are a royal pain to pull the boards. So, Arran is right, do the best you can. But, I also know what it is like trying to track down a 'new' problem, wondering if something failed or if it was some kind of error, so don't get carried away. From the looks of the screen, you have low B+ to start with, and /or low filament voltage, so start with filter caps in the power supply, then all bets are there will be some type of vertical sweep problems to track down, likely caps and those 'modules'. Anyway, interesting thread. Keep it coming.

[apERNA1985]

Hey guys sorry I haven't posted in a few days but I've ordered all the capacitors except for I think 2 from just radios and I'm waiting for them to come. In the meantime I decided to take the cover off the tube and clean it up it was so foggy you can barely see anything. Unfortunately once I started to see that it was clean I found out it has a crack in it are these common enough that I might be able to actually find another one. In the meantime I've gotten it pretty clear just using car polishing compound it does have some heavy scratches in it though I'm going to see if I can wet sand them. Also how do I get rid of the cheese and vomit smell? It doesnt want to air out.

[Bob Andersen]

No, unfortunately they are not common. Many others have been damaged over the years or destroyed when someone tries to ship one. So there is more demand than supply for good ones.

As for the smell, it's not going to go away. Periodic cleaning will help keep it down, but it will always come back. Seems to be worse when it's hot and humid. The screen is made from acetate butyrate (Tenite) and it slowly out gasses, fogs over, shrinks and warps. You may have noticed the same odor on screwdriver handles. It's tough and durable and is still made but they now incorporate an odor shield compound in the plastic formulation.

Every few years there is some talk about pooling resources and getting modern reproductions made from polycarbonate or something similar. Strong but no odor. It's not going to be cheap though. The initial cost to have a mold made would be $1,000s.

[apERNA1985]

I'm surprised with the abilities of 3D printing these days no one's just used a cad file and printed a new cover for us.  what's interesting is it seems very flexible almost like Tupperware or something. I'm pretty sure the crack was in it before I started which is the sad part but I think I know where there's another predicta I could buy just use the cover... there was a white milky film all over the screen both inside and out is that the cloudiness you were talking about I was able to actually scratch it off with my fingernail. It almost looks like dried toothpaste...

[Radioroslyn]

I believe it's called mold [Image: http://philcoradio.com/phorum/images/smi...n_razz.gif].
It will an annual event as it comes back along w/ the vomit smell.
I love Predictas.

[Bob Andersen]

That flexibility is one of it's desirable properties. Because it's tough and flexible it resists cracking better than most plastics. I'm not sure about that being mold. I think it might be that plastic slowly breaking down chemically. 3D printing is neither strong enough or transparent enough. Maybe in a few years, but not for now.

[Arran]

I can't speak for the cowl and faceplate on a Predicta but I have run into a number of post war plastic knobs that do much the same thing. What I have noticed is that if they are in a damp environment they get a build up of white residue, maybe it's mold, maybe not, and they tend to smell, if they are kept in a dry environment it doesn't seem to do that as much, such as the screwdriver handles I have. I've washed such knobs in a solution of trisodium phosphate and hot water, and the white stuff comes right off and the smell goes away, this is what I had around so there may be something better to try, also it can damage paint if the mix is strong enough. I don't know if Tenite II is the only plastic that does this as there are other knobs that seem to "mold" but they don't have the smell, so they were probably using more then one plant based plastic at the time.
  In terms of making new covers I think that polycarbonate would be a poor choice, it scratches very easily, it has almost zero resistance to U.V, I don't think it's any more resistant to cracking and breakage then the Tenite was (maybe less), and it's expensive. I've noticed that most plastics other then phenolics like Bakelite don't age very well, all things being equal Tennite II and cellulose acetate probably hold up better then most. I wonder if anyone has managed to get a hold of the Telstar people, they were making reproductions of Predicta TVs a few years ago, as colour sets, clearly they were making, or getting the plastic parts made somewhere?
Regards
Arran