View Full Version : Philco Predicta Debutante


Radiotronman
06-22-2016, 09:07 PM
Here is the picture of my recapped board and replaced out of tolerance resistors on the main board.

Radiotronman
06-22-2016, 09:09 PM
Progress so far, but there is still a lack of raster at the bottom of the screen. Not to figure out this issue.

Phil Nelson
06-22-2016, 09:51 PM
Have you tried adjusting the height and vertical linearity controls? Their location is shown in the Sams manual.

Hard to tell from your photo exactly what else is going on. Was the picture rolling or stationary when you took the photo?

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Radiotronman
06-22-2016, 10:04 PM
You were right Phil! After twiddling with the vertical linearity control, I was able to fill the screen. The rolling black lines are just camera sync issues, the screen had a nice steady raster. I'll get the electrolytics mounted a little neater next and apply a video source.

Radiotronman
06-22-2016, 10:09 PM
Almost forgot a pic of what the set looks like. It's the hotel white model with the instructions on the top of the cabinet for the user. I'm missing the contrast and volume knobs too.

Kevin Kuehn
06-22-2016, 11:35 PM
Looks nice. Are you leaving the couplates original?

Radiotronman
06-23-2016, 07:23 AM
Yes, I was advised by a Predicta restorer to leave them in unless there is a problem in those circuits.

WISCOJIM
06-23-2016, 11:20 AM
Almost forgot a pic of what the set looks like. It's the hotel white model with the instructions on the top of the cabinet for the user. I'm missing the contrast and volume knobs too.Could you share a good close-up shot of that hotel instruction label? I wonder if anyone has made repros of it? I've got a couple sets that could use replacement labels.

Thanks.

.

Radiotronman
06-23-2016, 09:53 PM
Here's the label on my set...still. Trying to figure out why I'm not getting anything when I hookup a pattern generator to the tuner leads.

WISCOJIM
06-24-2016, 12:18 AM
Here's the label on my set... Thanks!

Phil Nelson
06-24-2016, 12:45 AM
Trying to figure out why I'm not getting anything when I hookup a pattern generator to the tuner leads.Do you mean hooking up to the antenna connectors?

Be sure you are connecting the right output from your generator to the right spot on the TV. If your generator has an RF output and you connect that to the antenna terminals (and tune both generator and TV to the same channel), then you should get a pattern on the screen when you're TV is working normally.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Radiotronman
06-24-2016, 11:21 PM
So here's another case of a tube testing good, but doesn't work in the set. I changed out the 6AW8 video tube and finally got a crosshatch image!

Phil Nelson
06-24-2016, 11:46 PM
Wahoo!

Now, can you adjust the vertical linearity so that the squares are more the same height on the top & bottom? Often, you need to go back & forth between the vertical linearity and the height adjusters to get this right, since each adjuster may affect the other somewhat. If you do find that they're affecting each other (for instance, changing linearity also affects height), tweak each one a little bit each time, rather than trying to make it perfect all in one adjustment.

The vertical linearity shown in your last photo isn't awful, but if you can easily make it better with a little adjustment, why not?

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Radiotronman
06-25-2016, 12:14 PM
Yes, I'm gonna work on that next. I briefly tried yesterday and too much adjusting of either control will cause the set to quickly collapse to a horizontal line and flicker back.

Radiotronman
06-25-2016, 06:37 PM
Almost finished, but now I have no sound. I'm hoping it's a bad audio output tube or dirty pin sockets. I do get a buzz coming from the speaker.

Radiotronman
06-25-2016, 09:43 PM
Figured out that's coil near the audio output needed tweaked a little and I replaced the audio output tube. There was also a lot of interference in my set I couldn't figure out. I finally narrowed it down to the original telescoping antenna. I unhooked it on the back and the reception issue cleared right up! I'm considering this one restored!

Boobtubeman
06-26-2016, 05:56 PM
Lookin good!!

Might tweak the vert lin a bit...... Beaver has a case of cone-head syndrome hehe :D

SR

Radiotronman
06-26-2016, 06:18 PM
I tried and got it better, but too much movement on either the vertical linearity or height and the vertical collapses.

Phil Nelson
06-27-2016, 01:22 AM
too much adjusting of either control will cause the set to quickly collapse to a horizontal line and flicker back.I wonder if one or both of those controls needs cleaning. Did you ever clean them?

The reason I ask is that sometimes an old potentiometer will behave normally through part of its range, but conk out in other parts where it is gunky or worn out. One way to test this is to disconnect the potentiometer and then measure its resistance while turning it all the way back and forth. This works best with an analog ohmmeter where can watch a needle rather than try to interpret a stream of changing numbers. You should see the resistance change smoothly throughout the entire range of travel.

Or, you can just clean the control and see if that helps. This article has a little section with the basics of cleaning pots:

http://antiqueradio.org/FirstStepsInRestoration.htm

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

DaveWM
06-27-2016, 04:01 PM
those old pots are often bad, IIRC one or both are WW low ohms with built in range limits. Not to hard to find the correct replacement (you may have to add a limit resistor to be completely safe). You should fix it as its only going to cause issues later.