Philco Predicta Debutante

[Radiotronman]

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]

Originally Posted by Radiotronman

Here's the label on my set...

Thanks!

[Phil Nelson]

Originally Posted by Radiotronman

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]

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]

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]

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]

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]

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!

[Phil Nelson]

Originally Posted by Radiotronman

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]

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.