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


It is currently Oct Wed 27, 2021 12:32 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 62 posts ]  Go to page Previous  1, 2, 3, 4  Next
Author Message
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 12:19 am 
Member
User avatar

Joined: Sep Mon 16, 2013 2:42 am
Posts: 5101
Location: Tucson, Arizona U.S.A.
It also has to use U.S. scanning standards. European TV had different numbers of lines. But if the source is on the right frequency, "something" should show up on the screen even if it isn't intelligible.

_________________
Jim Mueller

Who's that swimming in the punch bowl?
It's Walter Wart, the freaky frog!


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 11:33 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 1549
Location: Belrose, NSW, Australia
If your signal happened to be PAL/CCIR (Euro) you will get a picture but it will be rolling. Vertical hold adjustment will usually lock it in.
The horizontal rate is not different enough not to lock.

If the modulator is also PAL/CCIR, you will get no sound, or buzzing maybe.

BUT if you ARE in the UK, all analog 625 line transmissions (and hence modulators) were/are UHF. Your Predictor is VHF and will NOT receive anything from a UHF modulator.

I could send you a modulator that will work.

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


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 3:28 pm 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
Here's an update. Turning the pattern generator ooutput all the way down, the pattern was still on the screen strong. I tried something different. I have a VCR that outputs to coax and/or LINE. Nothing showed up on COAX from channel 3 or 4. I tried output from LINE with a yellow AV cable and touching it to the tuner inputs on the Predicta. I actually got somewhat of an image. Obviously not a good image and the image is bouncing everywhere but something is coming through. The image is locked and solid when it's the pattern generator. Here is the image through LINE output. I didn't think the tuner could pick up a line signal but since nothing was coming through on the channel 3 or 4 coax output on the VCR, I thought I'd try it.

Also, I'm in the US


Attachments:

[ Play Quicktime file ] IMG_2064.mov [ 3 MiB | Viewed 1825 times ]
Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 5:45 pm 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2269
Location: Chicago, IL USA
I'm pretty sure Line Out is an unmodulated composite video signal. You can't run that through the tuner. Perhaps some stray RF modulated signal is making it's way from the VCR into the set ?

Can you please show us the back of the TV, the back of the VCR and how you are connecting them ?

Does the TV react when you change channels ? By that I mean the pattern of snow on the screen, the sound out of the speaker ? If it does we know the tuner is doing something at least.


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 6:07 pm 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
bandersen wrote:
I'm pretty sure Line Out is an unmodulated composite video signal. You can't run that through the tuner. Perhaps some stray RF modulated signal is making it's way from the VCR into the set ?

Can you please show us the back of the TV, the back of the VCR and how you are connecting them ?

Does the TV react when you change channels ? By that I mean the pattern of snow on the screen, the sound out of the speaker ? If it does we know the tuner is doing something at least.


Yes, I'll post photos when I get home of the back of the set and back of the VCR. The TV reacts when I change channels. Normal snow on the screen with static noise for every channel. When the pattern generator is connected, it has a sound hum that I believe the generator is outputting because the same sound happens on other sets when I hook that up.


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 8:33 pm 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
Here’s the back of the VCR (PIC 1) where I have hooked up coax to VHF out. Used a 75-300ohm transformer to the antenna leads on the Predicta Tuner (PIC 2). I also tried this attachment (PIC 3) that was a part of the original chassis. This is where I tried VIDEO OUT and got sort of an image. It’s better than getting no image when I try VHF output.


Attachments:
748A1A57-F853-468B-86A2-7D3771930C49.jpeg
748A1A57-F853-468B-86A2-7D3771930C49.jpeg [ 3.07 MiB | Viewed 1808 times ]
18C196E1-2279-451E-884B-0B23DA299793.jpeg
18C196E1-2279-451E-884B-0B23DA299793.jpeg [ 2.79 MiB | Viewed 1808 times ]
CA7F357D-8CAC-41B9-BAE1-54AF57ECC9ED.jpeg
CA7F357D-8CAC-41B9-BAE1-54AF57ECC9ED.jpeg [ 2.8 MiB | Viewed 1808 times ]
Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Tue 17, 2021 11:19 pm 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2269
Location: Chicago, IL USA
Was expecting to see a 75-300 balun screwed into the antenna terminals. How are you connecting everything up? I mean, literally, can you post a photo with it all connected together so we can look for any issues with the setup ?


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 18, 2021 3:11 am 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
bandersen wrote:
Was expecting to see a 75-300 balun screwed into the antenna terminals. How are you connecting everything up? I mean, literally, can you post a photo with it all connected together so we can look for any issues with the setup ?


Here's the setup of the 75-300ohm transformer hooked up to the attachment and straight to the tuner leads with the same result. I've been talking with a guy on instagram who has restored a few of these chassis, and on one, he's having the same problem as me. Pattern generator works great, but DVD or VCR doesn't inject a signal correctly. He suspects a broken trace in the tuner or IF circuit.


Attachments:
Screen Shot 2021-08-17 at 10.07.16 PM.png
Screen Shot 2021-08-17 at 10.07.16 PM.png [ 562.42 KiB | Viewed 1788 times ]
Screen Shot 2021-08-17 at 10.07.48 PM.png
Screen Shot 2021-08-17 at 10.07.48 PM.png [ 587.99 KiB | Viewed 1788 times ]
Screen Shot 2021-08-17 at 10.08.01 PM.png
Screen Shot 2021-08-17 at 10.08.01 PM.png [ 469.25 KiB | Viewed 1788 times ]
Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 18, 2021 5:37 am 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2269
Location: Chicago, IL USA
Pattern generator, VCR and DVD player all put out the same signal so a broken trace in the tuner or IF doesn't really make sense. If one works, they should all work.

Do you know what that lump is in the cable ? I'm guessing some sort of filter. Do you have a cable plain old 75 ohm cable ? Also how are you hooking up the pattern generator ?


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 18, 2021 3:39 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5832
Location: Ann Arbor, MI
bandersen wrote:
Pattern generator, VCR and DVD player all put out the same signal so a broken trace in the tuner or IF doesn't really make sense. If one works, they should all work.

Do you know what that lump is in the cable ? I'm guessing some sort of filter. Do you have a cable plain old 75 ohm cable ? Also how are you hooking up the pattern generator ?

From an earlier post, it looks like the pattern generator has it's output on channel 7. Or at least that is the channel it is received on. So the tuner may be working on the high channels but not on the low channels.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 18, 2021 7:24 pm 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 3519
Location: Dallas, TX
I've never actually worked on a Preditca at this point, but something doesn't look right.
The separate gizmo that has the short coax cable on one end and the twinlead wire going to the tuner.
Why would there be something that goes to the two antenna screws on the back cover to coax cable, then eventually changes to twinlead connections on the tuner?
I wonder if the gizmo is a balun that someone added in the past, incorrectly connecting the short coax to the screw terminals instead of some sort of coax connector on the back cover.
You might be losing a great deal of signal strength in that case.
The other picture with the clip wires going between the balun and the tuner (without that gizmo) should work better.

_________________
Tim
It's not the Destination, It's the Journey.


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 18, 2021 7:57 pm 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2269
Location: Chicago, IL USA
That gizmo is what's left of the base of the internal antenna. The coax is not original to the set. The tuner connects to the terminals on the back cover. Then either the internal antenna is connected or an external source is connected to the screw terminals.

Since you're not using the internal antenna, it should be disconnected.


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Fri 20, 2021 12:47 am 
Member
User avatar

Joined: Sep Mon 16, 2013 2:42 am
Posts: 5101
Location: Tucson, Arizona U.S.A.
Quote:
The coax is not original to the set.

Or, to put it another way, your set has been modified. Be on the lookout for other modifications as well.

_________________
Jim Mueller

Who's that swimming in the punch bowl?
It's Walter Wart, the freaky frog!


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Mon 23, 2021 4:04 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5832
Location: Ann Arbor, MI
Well we are not getting much of anywhere.
When I get back from vacation, I will try to look up the schematic and see what I can come up with
In the meantime could you verify that the pattern generator comes in on the same channel on other sets as it does on this set.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Wed 25, 2021 1:34 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5832
Location: Ann Arbor, MI
I can't find a schematic for this exact set, but looking at several schematics it looks like Philco used about the same tuner in many sets.
It looks to me that your tuner is working correctly on channel 7 (assuming that your pattern generator comes in on channel 7 on other sets). but is not working on channels 3 & 4.
This is entirely possible.

First a work-around so that you do not have to find the problem and fix it. There is a device called an agile modulator. These are often found on Ebay and are often made by Blonder Tongue. An agile modulator can be set to output on any channel. If you get one you could set it up to output on channel 7, which it looks like your tuner can receive. There are some on Ebay now.

Now about the problem. The Philco tuners that I have looked at use several rotary switches mounted on a single shaft. If you look inside the tuner you will see what I mean. There are coils mounted around the switches, one for each channel. The coils for channel 6 are larger than the adjacent coils as there is a large frequency change between channel 7 and channel 6. The channel 6 coil on the oscillator switch is adjustable. That would mean that there is some kind of core in it. If that core fell out or is otherwise missing then channel 6 and everything below will not come in. If it fell out it may be laying inside the tuner somewhere. If you have the Sams, the alignment instructions for the tuner should point you to where this adjustment is. You would not have to follow the alignment instructions, just figure out where everything is.

I had this problem on an RCA tuner. A core was inside a fiber tube that was glued inside the coil. The glue let loose. I found the core and tube and glued it back into the coil.

Look inside your tuner and see what you can see. Take pictures. Don't do anything at first, just post here about what you see.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Thu 26, 2021 5:36 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 5416
Location: Woodinville, WA USA
Tom Schulz wrote:
There is a device called an agile modulator. These are often found on Ebay and are often made by Blonder Tongue. An agile modulator can be set to output on any channel. If you get one you could set it up to output on channel 7, which it looks like your tuner can receive.
Here's an article with more details about using an agile modulator as an in-house TV transmitter:

https://antiqueradio.org/HomeTVTransmitter.htm

Easy and fun! And it lets you locate vintage TVs anywhere in your house, without stringing cables everywhere.

Regards,

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


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Aug Fri 27, 2021 6:25 pm 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5832
Location: Ann Arbor, MI
Also, have you cleaned the contacts in the tuner? Cleaning the contacts is usually required. People will tell you that if you spray DeoxIT all over everything in the tuner you will de-tune the tuned circuits. I have found that with a little care you can mostly confine the spray to the switch contacts. And DeoxIT will mostly evaporate in a few days eliminating the problem. And the de-tuning is not great enough to prevent receiving signals.

You don't want to move anything around in the tuner, but you can safely remove the cover, look around, and use contact cleaner on the contacts.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Sep Fri 17, 2021 3:09 pm 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
Final update. I knew I wasn't going crazy. I hooked up a B&K 1077B Television Analyst and the image came up perfect. But whenever I hooked up a VCR or DVD player, I couldn't pick up a signal. I ended up buying a Jerrold TV amplifier and hooked it up after the VCR and then output the Jerrold to the Predicta and the image and sound came in perfect. I had a hunch that the signal from the VCR wasn't strong enough to be picked up by the Predicta. Another person on Instagram reached out saying he was having the same problem as me in the past, pattern generator works, but tv box does not. I believe this fixed my issue. I'm sure there is another fix by checking certain components in the tuner but I didn't want to mess anything up in there. This seems like a good work-around. Thoughts?


Attachments:
Screen Shot 2021-09-17 at 10.01.55 AM.png
Screen Shot 2021-09-17 at 10.01.55 AM.png [ 787.86 KiB | Viewed 541 times ]
Screen Shot 2021-09-17 at 10.02.11 AM.png
Screen Shot 2021-09-17 at 10.02.11 AM.png [ 526.99 KiB | Viewed 541 times ]

[ Play Quicktime file ] IMG_7534 2_converted.mov [ 2.62 MiB | Viewed 541 times ]
Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Sep Fri 17, 2021 11:19 pm 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 1549
Location: Belrose, NSW, Australia
Sounds like the VCR output could be damaged and has low output, more likely front end of the tuner in the Predicta. But hey, it works....

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


Top
 Profile  
 
 Post subject: Re: Predicta Debutante Pattern Generator Works DVD player do
PostPosted: Sep Sat 18, 2021 12:40 am 
Member

Joined: Feb Thu 18, 2021 3:09 pm
Posts: 118
irob2345 wrote:
Sounds like the VCR output could be damaged and has low output, more likely front end of the tuner in the Predicta. But hey, it works....


That was my thought as well. I tried a few VCRs and DVD players and all had the same result. The VCR is also hooked up to another CRT set to make sure a signal is still going out of the VCR. But I guess this will be my fix for the time being. Hopefully I won't have to do this with all players I come across.


Top
 Profile  
 
Post New Topic Post Reply  [ 62 posts ]  Moderators: Mr. Detrola, 7jp4-guy Go to page Previous  1, 2, 3, 4  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: AJ2X, philsoldradios and 8 guests



Search for:
Jump to:  


































Privacy Policy :: Powered by phpBB