My Attempt at Predicta Restoration

[DaveWM]

the lin pot calls for a 1500 ohm with an internal stope at 180 ohms.

[Sandy G]

Curiosity killed the cat & all, but...Did you find this Predicta there in Germany, or did you ship it in from America ? If that was the case, I bet it set you back a small fortune in shipping charges...An' you're lucky it got there in 2 big pieces...(grin)

[PredictaNoob]

Originally Posted by Sandy G

Curiosity killed the cat & all, but...Did you find this Predicta there in Germany, or did you ship it in from America ? If that was the case, I bet it set you back a small fortune in shipping charges...An' you're lucky it got there in 2 big pieces...(grin)

I bought it from a guy in the States. I paid peanuts for the tele, but he swindled me on the postage (paid for priority x 2 boxes (each double boxed). He sent 2 boxes via parcel post (painfully slow and rough handling) and single boxed them. So I forked out about $100 for postage, and he spent about $55. Chiseler.
I guess I am lucky that there was only one small crack in the CRT cover. Could have been a lot worse.

[PredictaNoob]

Originally Posted by DaveWM

the lin pot calls for a 1500 ohm with an internal stope at 180 ohms.

Good catch. I hadn't even noticed that oddball until you pointed it out, (and the plastic insulated wire should have been the dead give away).
Its a flippin .5 MEG pot at 2W.
Sheesh, I'll order a proper pot when I order the resistors tonight.
Good news is that the caps arrived today.

[DaveWM]

half meg? geez there must have been a super critical adj. check check the tube resisitance on pin 9 of the 6dr7 vert out tube to ground. Should be around 450 ohms, give the meter a chance to settle in as there is a bypass cap across it. It must be set to nearly fully closed (min resistance).

[DaveWM]

C3 that bypasses it will most likely be open, it sets next to the Pwr tranny and gets baked, dries out, at least that was the case on two predictas I worked on.

[Phil Nelson]

Originally Posted by PredictaNoob

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?

If you just want to check operating voltages or eyeball things, a VCR signal is as good as any. To adjust things like linearity & centering, it's better to use a pattern generator that will give you a crosshatch pattern, cross, dots, etc. B & K made some Dynascan generators (1230, 1245, etc.) that are small enough to hold in your hand and often sell very cheap on eBay. Search for "color generator" or "pattern generator." For test gear like this, I'd generally avoid a vintage device, which will need the same kind of service as any old tube equipment and may also need calibration that you're not equipped for.

Phil

[PredictaNoob]

I've got a question about the electrolytics. I've read where certain sections of these TVs require exact component replacements. I had to go with a little higher rated caps on two stages on the 4-stage E1, and the single stage E1. The original ratings were 80mf at 350v (I used 82mf at 450v), and the other two were both 200mf at 150v (I used a 220mf at 160v). Are these eletrolytic stages required to be exact, or will the ones I have listed work?

[Phil Nelson]

The caps you listed will work. The difference in value is probably equal to or less than the manufacturing tolerance, in any case.

It's generally OK to go somewhat higher in capacitance with electrolytics, but don't go nuts. Don't substitute 100mfd for 22mfd, for instance. There's no advantage to using the 100mfd cap and it will be larger/more expensive.

Ditto with voltage ratings.

Phil Nelson

[PredictaNoob]

Originally Posted by Phil Nelson

The caps you listed will work. The difference in value is probably equal to or less than the manufacturing tolerance, in any case.

It's generally OK to go somewhat higher in capacitance with electrolytics, but don't go nuts. Don't substitute 100mfd for 22mfd, for instance. There's no advantage to using the 100mfd cap and it will be larger/more expensive.

Ditto with voltage ratings.

Phil Nelson

Thanks Phil. That's the procedure I normally follow with radios, but I had read somewhere that at least one section of these Predicta's requires exact value replacements. But I can't seem to find that website now, and I can't remember which section nor exactly which capacitors where involved. Dang!

[PredictaNoob]

Originally Posted by Phil Nelson

If you just want to check operating voltages or eyeball things, a VCR signal is as good as any. To adjust things like linearity & centering, it's better to use a pattern generator that will give you a crosshatch pattern, cross, dots, etc. B & K made some Dynascan generators (1230, 1245, etc.) that are small enough to hold in your hand and often sell very cheap on eBay. Search for "color generator" or "pattern generator." For test gear like this, I'd generally avoid a vintage device, which will need the same kind of service as any old tube equipment and may also need calibration that you're not equipped for.

Phil

I found a post tonight where a guy described using a test pattern card that he printed, taped to a wall and shot with his video camera. He then fed his video camera into the television he was working on. Sounds like a pretty simple 'poor boy' solution. Not the perfect solution, but perhaps good enough?

[PredictaNoob]

Originally Posted by Phil Nelson

If you just want to check operating voltages or eyeball things, a VCR signal is as good as any. To adjust things like linearity & centering, it's better to use a pattern generator that will give you a crosshatch pattern, cross, dots, etc. B & K made some Dynascan generators (1230, 1245, etc.) that are small enough to hold in your hand and often sell very cheap on eBay. Search for "color generator" or "pattern generator." For test gear like this, I'd generally avoid a vintage device, which will need the same kind of service as any old tube equipment and may also need calibration that you're not equipped for.

Phil

OK, I said the heck with it and bought a Dynascan 1245 from a guy on eBay for 10 bucks. I hope it actually works...

[Phil Nelson]

Originally Posted by PredictaNoob

Sounds like a pretty simple 'poor boy' solution.

Caught red-handed! That was my po' boy solution when I did my Predicta 1,000 years ago and didn't own a pattern generator. I had forgotten all about that scheme until you mentioned it.

http://antiqueradio.org/philc12.htm

Phil

[PredictaNoob]

Originally Posted by Phil Nelson

Caught red-handed! That was my po' boy solution when I did my Predicta 1,000 years ago and didn't own a pattern generator. I had forgotten all about that scheme until you mentioned it.

http://antiqueradio.org/philc12.htm

Phil

That is great Stuff! You're a legend, Phil (AKA Phil's Old Radios)
I love reading about your projects! I don't how many people you've helped, but you've sure helped me! Thanks.

[PredictaNoob]

I'm trying to replicate the control labels on the back of the cabinet top. It dawned on me that someone here might know the font that Philco used on these sets? Here's what I've got, so far. It isn't exact, but I'm rapidly losing concern about it...


This is Haettenschweiler 24 font size with a 4 point character spacing.