Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Tue 10, 2019 12:00 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 80 posts ]  Go to page Previous  1, 2, 3, 4  Next
Author Message
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 16, 2019 3:05 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Tom, and everyone else at the forum: I do believe I've found my problem! Looks like the I've got a bad VR1-A Height pot. Because the voltages going in were fine, but coming out were in the millivolts. Basically nothing. I tested the leads of the pot, and got zilch as far as resistance. Looks like it's open.

This was actually quite a thrill for me. Up to now I've known just enough to read a schematic and follow the instructions, but with this I'm finally getting a grasp on understanding the components and what they should be doing, and I owe it all to you folks who have helped me and helped me learn!

So my next question is as far as replacement goes on this pot....the schematic says it's a 3M ohm rated pot, but gives no floor or stop value, so does this mean this pot goes from 0 ohms resistance up to 3M? And if that is the case, for the purpose of testing, would I be safe to bypass this pot altogether, just to see if I've eliminated the problem, or do I still need some kind of resistance in place to "act" like the pot?

Thanks so much all!

BR


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 16, 2019 4:24 pm 
Member

Joined: Feb Thu 28, 2019 7:48 pm
Posts: 402
Location: Lawrenceville, Illinois 62439
That may be a 3,000 ohm - I can't recall when they switched from "M" to "K" to signify thousand.
If you find a Philco part number, I can dig through my NOS parts and see if I've got one to compare readings.
Dan


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 16, 2019 4:57 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Dan that would be a huge help. The part in question is the VR1 (33-5593-3). It's a dual pot that controls height and centering. The heigh pot (the one I'm interested in) is indeed 3 meg, and the adjacent pot (for the center) is 100K.

Dan, are you the same fellow on the Vintage Television Collectors FB page with whom I have corresponded about parts? I've posted there as well about my Philco Predicta.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 16, 2019 6:34 pm 
Member

Joined: Feb Thu 28, 2019 7:48 pm
Posts: 402
Location: Lawrenceville, Illinois 62439
No, I'm not. I may have to visit that site.
I dug around; don't have any of that part number, nor any close matches.
I would temporarily try jumpering in say a 1 meg, just to evaluate the performance, adjust up or down by 500K to see any change.
If it improves, then you can look in earnest for a replacement.
Dan


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 2:04 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 591
Location: Belrose, NSW, Australia
If the oscillator isn't running, the tube will turn hard on and pull the plate voltage (pin 6) to near the cathode voltage.
Pulling the tube will stop this from happening and so the plate pin will go up to nearly B+ or B+boost, wherever it's connected.
Since it doesn't, most likely it's a bad resistor in the height control circuit, or the pot itself. Whatever is in between the B+ and the plate, pin 6.
If there is a transformer and it has a winding in the plate circuit, that is a common failure point. Open circuit or breakdown to frame.

_________________
Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 2:38 am 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Success! It was the pot. Wired in a similarly rated resistor and got raster! It's not terribly pretty, and I'm not getting any picture or sound, so there are still issues to be sorted, but I'm closer!


Last edited by Brianruns10 on Apr Wed 17, 2019 3:52 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 12:31 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 14902
Location: Fernandina Beach, FL
Now that you have figured out what was causing the squashed raster, how about fixing the picture size to maybe 800 pixels wide?

_________________
Don


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 2:44 pm 
Member

Joined: Aug Thu 20, 2015 3:09 pm
Posts: 1263
Location: Albion, CA, USA, 95410
Don Cavey wrote:
Now that you have figured out what was causing the squashed raster, how about fixing the picture size to maybe 800 pixels wide?

Pretty please?!


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 3:26 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Sorry I tried but couldn't get it resized. Maybe a mod can edit it?


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 3:28 pm 
Member

Joined: Sep Fri 07, 2007 2:27 am
Posts: 6227
Location: Grand Chute, Wisconsin
Here's a repost of it. Now you can just delete the earlier image.

Attachment:
fd.jpg
fd.jpg [ 81.67 KiB | Viewed 550 times ]


.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 3:53 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Thanks! Since I've solved my raster issue I'm going to start a new thread as I begin work on figuring out why I don't have picture or sound. Thanks for all your help!

BR


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 4:07 pm 
Member

Joined: Sep Fri 07, 2007 2:27 am
Posts: 6227
Location: Grand Chute, Wisconsin
Brianruns10 wrote:
Thanks! Since I've solved my raster issue I'm going to start a new thread as I begin work on figuring out why I don't have picture or sound. Thanks for all your help!

BR

I'd rethink that. It may be best to continue the story on this set's progress. Often later problems relate to work done in earlier stages. That will make this easier to follow along and share help when needed. Maybe just change the topic title to "Predicta 10L43 restoration" or something similar. No need to have multiple threads on one project.

.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 5:24 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5046
Location: Ann Arbor, MI
There is a rule for this forum that says one thread per set. I am surprised that the moderators have not complained already.
You can change the subject of this thread by editing the subject in the first post.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 5:32 pm 
Member

Joined: Sep Fri 07, 2007 2:27 am
Posts: 6227
Location: Grand Chute, Wisconsin
Tom Schulz wrote:
There is a rule for this forum that says one thread per set. I am surprised that the moderators have not complained already.
You can change the subject of this thread by editing the subject in the first post.

When I made my previous post about not starting a new thread, I didn't realize that there are already more than a half-dozen threads already going on about this one set. Way out of control.

.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Wed 17, 2019 5:48 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Sorry I didn't know.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 23, 2019 4:11 am 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Welp I've made further progress, having found a shorted resistor in my tuner, and swapped out the tube diode which was marginal. I now have a good healthy TV snow, which is encouraging, but blast it all, still no picture nor sound, not even static. I shall resume testing things, but boy what a stumper.

I should've listened to that wizened old fellow with the Maine accent, who warned me when I bought this TV, "Some things are better...dead!"

BR


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 23, 2019 4:43 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5046
Location: Ann Arbor, MI
What are you using to feed a signal to the TV?

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 23, 2019 5:17 am 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
I have a VCR with an adapter, and also a signal generator/calibrator box. Zilch on both.


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 23, 2019 6:28 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5046
Location: Ann Arbor, MI
Hmm... Snow but no picture. Either you are somehow not setting the tuner to the same channel as your signal source is on or the oscillator section of the tuner is not working or is not at the right frequency.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta 10L43 First Powerup...squashed raster
PostPosted: Apr Tue 23, 2019 6:47 pm 
Member

Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
yeah both signal output devices have options for channels 3 or 4, both of which I've tried, and I've cycled through all the channels on the tuner. I did have to replace multiple resistors on the tuner; one was shorted and several others were out of tolerance. I wonder if that means I'll have to recalibrate?


Top
 Profile  
 
Post New Topic Post Reply  [ 80 posts ]  Moderators: 7jp4-guy, Mr. Detrola Go to page Previous  1, 2, 3, 4  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: 1988bluebird, thomas13202 and 5 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB