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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 4:06 pm 
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Adjust the HORIZONTAL HOLD. As you adjust it, the black and white stripes should get wider if you are going in the right direction. you should reach a point where the image either locks, or "floats through". Once that happens and you adjust the vertical hold to stop the image from rolling, you'll be able to see what else is wrong.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 4:28 pm 
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irob2345 wrote:
Adjust the HORIZONTAL HOLD. As you adjust it, the black and white stripes should get wider if you are going in the right direction. you should reach a point where the image either locks, or "floats through". Once that happens and you adjust the vertical hold to stop the image from rolling, you'll be able to see what else is wrong.


And to add to the above ^^ the slanting of the lines is not because of the yoke position. As mentioned, try the two "Hold" controls first. Looking better!!!

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 5:11 pm 
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Notimetolooz wrote:
There is something additionally going on, the screen look like the problem is not only the horizontal frequency.
Maybe the yoke is rotated causing the lines to slant more than they should. I wonder about the horizontal being off so far, I would think the H.V. would be effected more. I suppose the vertical frequency is off also.

That amount of slant is not unexpected for a mis-adjusted horizontal hold control. If the horizontal hold does not have enough range to sync the picture then the horizontal frequency adjustment (a course horizontal hold) can be used to bring the horizontal in .
The vertical will almost certainly be off until the vertical hold is adjusted. But you have to get the horizontal to lock in first.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 9:20 pm 
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Location: Kansas City, Missouri
So acting upon your excellent advice, I've been revisiting all the control settings, including going through the steps of adjusting the horizontal oscillator. And in so doing I accidentally made progress, but I'm not quite sure how to interpret these results. As I was finishing the steps of adjustment, I went to tweak the T7 ringing coil with a hex wrench. But the first one I grabbed was ever so slightly undersized, and dropped through the coil to the bottom. And when I did that, I got my signal grid! It's not very pretty, but it's a grid, and it's much closer to the picture I should be getting:

Image

The problem is, I can't seem to replicate this image, unless the dang wrench sits inside the coil, which is obviously not what the manufacturer intended. So it's a result, but I'm unsure how to interpret it, and just how to go about further improving the image quality and stability. So close, yet so far. Also, in case this information is relevant, there are a few coils on the ringing coil that are a bit loose fitting around the top of it, and I wonder what if any impact this has on its performance? Should I seek to repair it?


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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 9:58 pm 
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It sounds like you are using a metallic tool, which is a "no-no". A metallic tool effects the magnetic field of the coil, also because they are harder they can lead to the ferrite core cracking. The tool should be plastic or wood. I've heard of people carving them out of dowels or chopsticks. A tool was available that had a slug of ferrite in one end and a piece of brass in the other, you lowered it down the coil and depending on which end helped the problem you knew whether you needed to increase or decrease the inductance.
However this may indicate that an associated capacitor may be bad.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 10:02 pm 
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It could also be that you have the horizontal locked but the video signal is missing the high frequency range and so smears out the details like the vertical lines. In other words the video amp or the IF amps are limiting the signal.
Set the generator to display only the vertical lines and see what you get.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sat 01, 2019 10:37 pm 
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Thanks all, and I will be cautious going forward about using metal tools!

BR


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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 12:23 am 
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Brianruns10 wrote:
Thanks all, and I will be cautious going forward about using metal tools!
BR

No, don't be cautious -- stop using them! Adjustments will be frustratingly difficult at best (and maybe futile) if you use metal tools to adjust coils, plus the aforementioned possibility of physical damage. Additionally, a slip of the hand with a metal tool in a powered chassis can mean an inadvertent short circuit, or electrocution. There are almost no adjustments in any television set that require a metal tool. We want you and your Predicta to survive!

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 1:45 am 
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This is a good example of that it is best to have a mentor when someone gets into restoration.
The old salts that are likely to help a newbie on a forum take things like this for granted, they know eating hot soup with your fingers isn't going to work (and you might burn your fingers).
On the other hand a newbie doesn't know what questions to ask.
It helps when someone gets started to check out other threads and other info even if they aren't about the equipment that they are presently working on. I can't count the times I have read something that didn't relate to what I was doing at the time that revealed a nugget of useful info that came in handy later.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 3:44 am 
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Finding a mentor is easier said than done, and please don't call me a newbie. I'm learning as best I can, and remember, if this hobby is to survive, you're going to need young people like me continuing this work.


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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 4:12 pm 
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I certainly meant no insult. I was simply referring to someone without a lot of experience with subject.
I didn't mean that you were not learning. Yes, mentors are just about non-existent now, but an experienced person looking over the shoulder of someone doing something new can help spot problems. It is hard on a question and answer forum like this one to cover some details that experienced people have taken for granted that everyone knows.

Anyway, if you set your pattern generator to display vertical lines and you still see horizontal lines then you have a problem with the horizontal sweep. If the horizontal lines disappear then the problem is with the video signal system.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 5:04 pm 
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Location: Belrose, NSW, Australia
Yes, you need non-metallic tools. There's no way you would have known this.

You can get the correct tools but in the meantime it is possible to file down a plastic knitting needle to do the job. Be careful you don't force the slug or it could split and be VERY hard to remove.

If your pattern generator has something other than a cross-hatch pattern, like a stair step, you should find it easier to see what you are doing.

I think the instructions say something about shorting that coil first while you adjust the other one, is that right?

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Sun 02, 2019 5:53 pm 
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irob2345 wrote:
I think the instructions say something about shorting that coil first while you adjust the other one, is that right?

No, this set has only one coil. Here is a link to the schematic http://www.earlytelevision.org/pdf/philco_h3410_predicta_princess_sams_466-1.pdf.

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 Post subject: Re: Predicta 10L43 [Edit: Update]
PostPosted: Jun Mon 03, 2019 8:45 pm 
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This is about the cheapest readily available tool set that would do.
https://www.amazon.com/Velleman-Plastic ... B004X7HSU6

GC Electronics has made the standard type of tools for many, many years.
I think this is very similar to the set I got when I started out.
http://www.intertexelectronics.com/GC-E ... P9186.aspx

I've picked up more over the years, including some I made myself.

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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 3:41 pm 
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Joined: Dec Tue 10, 2013 4:36 pm
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Location: Kansas City, Missouri
Good Morning All,

Well, I've made some nice progress, thanks to your advice, and a collector who sold me some spare parts. I replaced the ringing coil (which was in rough shape and had a stuck core), and I also found a mistake in one connection on the N6 couplate I rebuilt. When that was all done, I found I was able to obtain a very nice pattern from my signal generator! I've posted a photo below (please ignore the weird shadow effect on the top and bottom of the CRT, this was due to my shutter speed, and was not visible in person). Needless to say I'm getting very encouraging results.

Image

But I still have a few problems. 1, there is some residual ghosting that resembles a pinprick pattern between the gridlines. Now, this could be an artifact of my signal generator, so I will do further tests tonight with a actual video source. The other, more serious problem is that I'm having difficulty maintaining this on-screen pattern. Meaning, when I shut the TV down, and start it up again, I do not obtain the same results, I have to recalibrate. And when I do get a nice pattern, if I let it sit, it will eventually start to slip out of sync again. Basically it needs constant attention to maintain a nice stable picture.

And this might be relevant: I was following the predicta manual's procedure for calibrating the horizontal, which involves shorting the ringing coil with a jumper, and then doing alignments on the other controls. What I've found is, I am able to most readily obtain a good image when the ringing coil is shorted, and when I remove the jumper, I immediately lose the image, and have great difficulty regaining it. The best results are when I short the coil entirely, which is obviously not ideal.

What could this indicate to you? What would your thoughts be as to next steps?


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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 4:06 pm 
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Joined: May Thu 14, 2015 4:15 pm
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Location: Dallas, TX
Looks like things are coming along pretty good.
That "ghosting" problem may be your signal generator ( digital pulses from count down circuits leaking out) or it could be a case of the video amplifier "ringing".
https://en.wikipedia.org/wiki/Ringing_(signal)
Have you tried adjusting the contrast on the TV to get rid of it?

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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 6:21 pm 
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By ringing coil do you mean horizontal oscillator coil?

Sweep sync issues can be a few things. If only one axis is slipping out of hold then the oscillator for that stage or the filters feeding it sync are not working properly. If both axes are slipping out of sync then the problem lies with the sync separator or possibly a misadjusted AGC control.

Double check with a normal signal source before going to deep some pattern generators are hard to properly sync to by virtue of not putting out standard sync signals.

Oscillators can drift in normal opperation...If it needs the hold adjusted during the watching of a full length movie there is room for improvement and reason to seek it.



Brianruns10 wrote:
Good Morning All,

Well, I've made some nice progress, thanks to your advice, and a collector who sold me some spare parts. I replaced the ringing coil (which was in rough shape and had a stuck core), and I also found a mistake in one connection on the N6 couplate I rebuilt. When that was all done, I found I was able to obtain a very nice pattern from my signal generator! I've posted a photo below (please ignore the weird shadow effect on the top and bottom of the CRT, this was due to my shutter speed, and was not visible in person). Needless to say I'm getting very encouraging results.

Image

But I still have a few problems. 1, there is some residual ghosting that resembles a pinprick pattern between the gridlines. Now, this could be an artifact of my signal generator, so I will do further tests tonight with a actual video source. The other, more serious problem is that I'm having difficulty maintaining this on-screen pattern. Meaning, when I shut the TV down, and start it up again, I do not obtain the same results, I have to recalibrate. And when I do get a nice pattern, if I let it sit, it will eventually start to slip out of sync again. Basically it needs constant attention to maintain a nice stable picture.

And this might be relevant: I was following the predicta manual's procedure for calibrating the horizontal, which involves shorting the ringing coil with a jumper, and then doing alignments on the other controls. What I've found is, I am able to most readily obtain a good image when the ringing coil is shorted, and when I remove the jumper, I immediately lose the image, and have great difficulty regaining it. The best results are when I short the coil entirely, which is obviously not ideal.

What could this indicate to you? What would your thoughts be as to next steps?


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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 6:34 pm 
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Joined: Dec Tue 10, 2013 4:36 pm
Posts: 162
Location: Kansas City, Missouri
Electronic Memory wrote:
By ringing coil do you mean horizontal oscillator coil?


Yes. The Philco manual alternately calls it the horizontal ringing coil, or the horizontal oscillator coil.

Electronic Memory wrote:
Sweep sync issues can be a few things. If only one axis is slipping out of hold then the oscillator for that stage or the filters feeding it sync are not working properly. If both axes are slipping out of sync then the problem lies with the sync separator or possibly a misadjusted AGC control.


The vertical axis dials in nicely and holds reasonably well. It's the horizontal axis that that seems to be most sensitive and fussy.

I'll do some tests tonight with a true video source, to see if it isn't my signal generator that is proving problematic, and will report back.


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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 6:39 pm 
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Location: Dallas, TX
In a previous photo you posted it looks like your pattern generator can generate just the horizontal line pattern. Try that setting and see if the ghosting disappears. If it does then the ghosting probably isn't ringing.
As a matter of fact you should probably try all the patterns to see if anything interesting happens.

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


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 Post subject: Re: Predicta 10L43 [Update: 6/10/19]
PostPosted: Jun Mon 10, 2019 6:49 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 1573
Location: Dallas, TX
One other thought. This set seems like the contrast control may effect the sync pulses.
You might have the brightness and contrast set too high and with the strong signal coming from the generator it could be overloading the sync circuits. Early TV did not have the bright screens you might expect today.

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


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