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 Post subject: 1959 Philco Predicta Restoration Thread
PostPosted: May Sun 26, 2019 11:38 pm 
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Posts: 276
Location: Bloomington, IN, 47401
To recap, this is the Predicta I picked up in Indy for $150. Search lower for the thread about it being for sale, and pix of the unit itself.

I used my variac to bring it to 50VAC for 30 minutes, 70VAC for another 30 minutes, 90VAC for 15 minutes, and then up to 117 VAC.

All tubes appear to work - except the picture tube. Not even the faintest glimmer of a single pixel from it. Audio was strong, so that's good. No odd smells, and all components appeared in good condition after a dusting/cleaning (enough to easily read the circuit board info).

I have a printout of the SAMS Set 466 Folder 1 Service Manual for the 10L43 chassis (it's actually an 11L43 chassis, but that just signifies that it's the motel model; the manual covers the models that use the 10L43 chassis), so will be going through that. Any ideas on where to start for the video portion, or a way to apply power to the picture tube to see if it's even functional?

Do you recommend a full recapping? Don't know if I have the money for that.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Sun 26, 2019 11:52 pm 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 276
Location: Bloomington, IN, 47401
Upon further study of the manual, I can't confirm if the 1st, 2nd and 3rd Video IF tubes were lit. Pretty sure the 3rd IF was, but not certain of the other 2. Still, I should see snow with a good picture tube, correct?


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Mon 27, 2019 12:32 am 
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Location: Detroit, MI USA
You should at least have a blank raster, even if none of the IF or tuner stages are working. If those are working, you should see at least snow on the raster.

Yes, you must recap the entire set, it won't work properly unless that's done.

First step at this point is to find someone locally with a CRT tester who is capable of testing that set's unique CRT. You need to know if it's good or not before proceeding.

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Experience is what you gain when the results aren't what you were expecting.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Mon 27, 2019 1:34 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 276
Location: Bloomington, IN, 47401
Mr. Detrola wrote:
Yes, you must recap the entire set, it won't work properly unless that's done.


Yeah, that's what I figured.

Quote:
First step at this point is to find someone locally with a CRT tester who is capable of testing that set's unique CRT. You need to know if it's good or not before proceeding.


As it happens, I have a B&K Model 440 CRT Rejunvenator Tester! Got access to the back of the picture tube (a 17DRP4), hooked up the tester, and got the following results:

Settings for the test
Image

Shorts Test
Image

Interpreting the Shorts Test
Image

Emissions Test
Image

I actually misread the Tester and thought I had an H-K short, so applied the procedure to repair Inter-Element Shorts as detailed in the manual. Namely, setting the control to "Remove Shorts", waiting 30 seconds, then pressing the "Dynamic Intensifier" button for 2-3 seconds. The result was that the Emissions went from 500 to over 600.

So, it looks like I have a good picture tube, which narrows down the problem a bit!

[Never thought I'd actually use that CRT Tester, but turns out to be money well spent! Just $20 from Goodwill, and it has all the parts! Can work on B&W and Color tubes!]


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Mon 27, 2019 1:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1944
Location: Lafayette, CO
I use the same tester. I smile when l see the two half lights slowly brighten. Craig


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Mon 27, 2019 3:24 am 
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Location: Redlands CA
Using the Dynamic Intensifier may have bumped the emissions up slightly, but it probably shortened the life of the tube.
The older testers just used brute force to blast the crud off the cathode, often stripping it of usable material in the process.

The lack of a raster is probably due to a lack of high voltage, often due to a faulty horizontal oscillator.
Be extremely careful around the Flyback transformer, they are always old and crispy on the Predicta and can be damaged easily.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Mon 27, 2019 3:38 am 
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Location: Bloomington, IN, 47401
Thanks for the feedback. I plan to take it slow.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Wed 29, 2019 3:49 am 
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Joined: Sep Mon 28, 2009 1:53 am
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Location: Bloomington, IN, 47401
Used my TV-11 Tube Tester on some of the tubes (it's too old for many of the TV-specific, late-1950s tubes). The HV Rectifier (1G3GT/183GT) tested bad (~26) which could explain the lack of the raster. Four other tubes tested good, all in the mid-70s range. 9 other tubes need testing, but many of those go to the audio, and I know that's working.

I'm still having 2nd thoughts about working on it, as my knowledge is lacking. My EE201/202 professor from Purdue (40+ years ago), stated at the end of the 2nd semester, "Now you know enough to be dangerous!". By that, he meant we students would probably overestimate our knowledge and get into trouble. I've kept that in mind all these years, and at this point, I feel like I'm edging into trouble.

So, if someone wants to take over the restoration, I'll sell the TV and my B&K Model 440 CRT Tester for $200, local pickup in Bloomington, IN (unless you're willing to pay Pak-Mail to pack and ship it). I took the big risk at $150 to see if this thing was a boat anchor or not, and we know most of it works! I'd rather not part it out, but I need to recoup my investment.

PM me if you're interested.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Wed 29, 2019 4:04 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 276
Location: Bloomington, IN, 47401
Decided to get a replacement rectifier tube before giving up completely. Only $5 or so on eBay, which is cheap enough to satisfy my curiosity. If I get a raster, I might sit down with a local radio & TV guy to learn more about what I need to do.

There's a good electrical parts store in town (Stansifer Electronics), and they have a bunch of old gear on shelves, including what looks like an Atwater-Kent Model 10 that's just begging for a restoration! Unfortunately, the guy who owns it (a relative of a Stansifer employee) won't let anyone touch it. A travesty! But the guys there should be more than willing to help me if I need it. Kind of slow there most days, and I'm sure they'd get a kick out of seeing the Predicta.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Wed 29, 2019 3:26 pm 
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Location: Chicago, IL USA
1B3 rectifier tubes typically test low when they are good. Testers often state something "good > 20" in the margin of the setup chart. They also rarely go bad. So I hate to say it, but I doubt that's your problem.

No, these are not the easiest TVs to work on, but with methodical, careful work you can get it going. You've also got the advice of all the forum members and numerous restoration write ups and videos to help.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Wed 29, 2019 7:07 pm 
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Joined: Sep Mon 28, 2009 1:53 am
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Location: Bloomington, IN, 47401
bandersen wrote:
1B3 rectifier tubes typically test low when they are good. Testers often state something "good > 20" in the margin of the setup chart. They also rarely go bad. So I hate to say it, but I doubt that's your problem.


It's only $5, so it can't hurt.

What does kind of hurt is that I sold a lot of ~275 tubes and a GE Serviceman's case for $150 about 2 weeks ago! That tube might have been in there!

Anyone around Bloomington, IN have a better tube tester? I can bring the tubes to you, or you can come by and have a closer look at the Predicta.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: May Thu 30, 2019 4:52 pm 
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Joined: May Sun 07, 2017 11:35 am
Posts: 584
Location: Belrose, NSW, Australia
The 1B3 will be OK if you get any reading at all. Just about any fault in the horizontal deflection circuit will stop it from lighting up, and you need a dark room to see it glowing anyway.

With old TVs, now that they are 50 or 60+ years old, bad tubes are almost never what stops them from working, unless there is obvious broken glass and a getter (the silver/grey stuff on the inside of the glass) that has gone white. Bad passive components are the cause of 99% of faults. A low emission tube will almost never stop the TV completely so tube testing is a bit of a waste of time.

Please do not start dismantling things randomly looking for faults. You will not find them this way and you will likely break stuff that will be hard to replace.

Start by checking voltages on the CRT socket and around the hor. OP tube. Tell us what you get. Don't put your meter on the top cap of the tube or it (the meter) may be instantly destroyed.

Disturb stuff as little as possible. Measure first. That's the secret to a quick, successful repair with the minimum of pain.

You will probably have to replace all the paper caps in the TV. I normally replace a few critical ones first (B+Boost cap, grid 1 couplers of horizontal and vertical output stages) and start measuring. Get the TV working (however badly) then replace the paper caps a few at a time. This way, when you make a mistake you will be able to find it easier.

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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Sat 01, 2019 9:07 pm 
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Posts: 276
Location: Bloomington, IN, 47401
The SAMS pages indicate that if there's sound but no raster, to check the Horiz. AFC diode, and tubes V9-V13. The Horiz. AFC diode is a Dual Selenium Diode, and I'm not sure how to test it. Most articles I could find on selenium diodes (usually the selenium plate diodes vs. the small package in the TV) suggest replacing any selenium diode with a 1N4007 and a limiting resistor of the proper value. There should be 10V on pin 1, 7.5V on pin 2, and pin 3 is GND.

Image

I can't test V9 or V10, as my tester (TV-11) doesn't have those listed on its roll list or in the supplemental list. V11-V13 tested good.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Sun 02, 2019 4:58 am 
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Location: Waxahachie Texas
I use 2 1N4007 diodes to replace the AFC diode. You don't have to worry about adding a resistor in this case.

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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Sun 02, 2019 5:48 pm 
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Location: Ann Arbor, MI
For the AFC diodes, it would be better to use small signal diodes. Those little red ones. The 1N4007 and such can be slow to turn on and off. That is not a problem at 60 HZ but could cause poor performance at 15700 HZ. Now if Radio Shack still had stores everywhere, I would say that you should go to your nearest Radio Shack and get some. Perhaps someone will chime in with their favorite source of such things.

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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Sun 02, 2019 8:48 pm 
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Location: Bloomington, IN, 47401
Tom Schulz wrote:
For the AFC diodes, it would be better to use small signal diodes. Those little red ones. The 1N4007 and such can be slow to turn on and off. That is not a problem at 60 HZ but could cause poor performance at 15700 HZ. Now if Radio Shack still had stores everywhere, I would say that you should go to your nearest Radio Shack and get some. Perhaps someone will chime in with their favorite source of such things.


I think I'll try the 1N4007, just to see if the No Raster issue is the AFC diode. If I get a reaction, I'll then look into a better replacement.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Mon 03, 2019 12:21 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 276
Location: Bloomington, IN, 47401
No reaction on the 1N4007s for the AFC diode. I had good filaments on all tubes, including the picture tube. Audio was still strong. Nothing else has been replaced at this point.

Still 2 tubes I haven't been able to test because the TV-11 is too old, and they're 2 tubes that need to be checked if there's no raster. I'm going to my local parts store tomorrow (no more Radio Shacks in Bloomington). They may have a tester on hand, or will know someone who has one.


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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Mon 03, 2019 4:50 am 
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What kind of parts store do you have? They may well have small signal diodes. They are also called high speed diodes or switching diodes. 1N4148 is a common type. It won't hurt anything to try 1N4007s, but if you end up with the horizontal locking in only over a narrow range of the horizontal hold control, try better diodes.

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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Mon 03, 2019 6:08 pm 
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Location: Waxahachie Texas
Tom Schulz wrote:
What kind of parts store do you have? They may well have small signal diodes. They are also called high speed diodes or switching diodes. 1N4148 is a common type. It won't hurt anything to try 1N4007s, but if you end up with the horizontal locking in only over a narrow range of the horizontal hold control, try better diodes.

Tom, Good point! I'll use 1N4148. Will 1N914B's work?

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 Post subject: Re: 1959 Philco Predicta Restoration Thread
PostPosted: Jun Mon 03, 2019 8:34 pm 
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Location: Dallas, TX
I think the 1N914 are very similar to 1N4148. You are right no resistors need to be added to this low
current application.

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