# Vertical Position on TV set



## txe5502 (Apr 11, 2008)

Hello,

I have an RCA XL-100 TV set and it works great except for one thing. When I connect it to a DVD player, it has these horizontal lines at the top, I have figured out that this is caused by an overscan or underscan. I was adjusting the vertical height, but apparently the problem is more related to vertical position than vertical height, because when I adjust the vertical height properly, there is a gap at the top of the picture, but not at the bottom. I would appreciate it if someone here could tell me how I should go about adjusting the vertical position of this TV. If I am not missing anything, there are no adjustments for this on the outside of the TV set. Vertical hold somewhat remedies the lines at the top of the screen as well as Vertical height.

Any help with this is greatly appreciated

Thanks,
Tyler


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## Done_Fishin (Oct 10, 2006)

are you trying via RF or Scart .. used to be some problems with VCR's years back that would not synch properly using RF channels and the TV manufacturers then created special "memory positions" to synch the incoming signal. 

try using your AV, O or last channel position and selecting the RF channel or even SCART if it has one .. sorry the TV you quote is not one that I am familiar with, living "across the water" as we do


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## txe5502 (Apr 11, 2008)

Well, I looked up this "scart" connector, and I have never saw something like this on a TV in America, not even on super duper new TV's like my dad's high def projection TV. And my TV highly likely has no "memory" in it to prevent overscan/underscan, as it inputs RF VHF via 300 ohm lugs on the back. I connect my DVD player via channel 3 (of course, this is standard), and an RG6/59 to 300 ohm antennawire adapter. Actually, I find it very strange that everything displays correctly except for DVD's, I even have a combo DVD/VHS player which plays VHS tapes 100% correct, but DVD's on it create these horizontal lines at the top, my other DVD player that only plays DVDs does this as well, but it's setup menu does not create horizontal lines at all, only DVD playback. One more thing is that these horizontal lines are there at first, then once in a while, they fade out, then immediately fade back in, I find that very interesting. When I adjust the V-Hold and V-Height this affects the horizontal lines drastically, they become closer together (and closer to the top) or farther apart (and take up more of the screen) as I adjust these settings. I do believe I have isolated the problem to being an overscan/underscan now though.

Still looking for suggestions though

Thanks,
Tyler


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## Done_Fishin (Oct 10, 2006)

you have just confirmed my suspicions that you are watching DVD's via RF (a lead similar to your aerial cable).

I probably haven't expressed myself well .. by memory I mean the program number that you have used to store your DVD channel. Try Program position 0, ie select the program number 0 and then tune in to your DVD channel .. your set should have a program number that will store the channel and when you tune in will synch properly .. this problem goes back to the days of B&W sets and VCR's . If there is an AV program position on your TV try using that or the very last program number.
to try to make myself clearer .. program numbers are the programmable locations that you store your TV channels into .. frequently starting at AV or 0 and probably having anything from 8 to 99 locations or "memories" where you can store your TV stations of choice


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## txe5502 (Apr 11, 2008)

This TV is not programmable, it uses a regular old channel knob with VHF channels 2 through 13. There is nothing in this TV set that uses an on screen display, it uses a knob for channel selection.


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## Done_Fishin (Oct 10, 2006)

If it's that old then its the classic symptoms of inability to synch at the start of framing .. can't remember exactly what the cause is .. something to do with the way the transmitted signal has information imposed on it which impede synchronization of the picture.

I've been googling various phrases about this without finding what I am looking for , which is unfortunate.. means I haven't found the correct phrase yet ..


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## txe5502 (Apr 11, 2008)

Well, I have reason to believe it is some sort of overscan or underscan, because when I adjust vertical hold and vertical height, it affects the distance between these horizontal lines, as well as how far down the screen they go. What is odd is that at the DVD Menu, the horizontal lines are not present, they are also not present on a VHS tape played by the same player (combo DVD/VHS), nor my Digital ATSC to analog converter box, nor my N64/NES game console, only during DVD playback, nothing else, not even the menu...


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## Done_Fishin (Oct 10, 2006)

When you are adjusting the vertical scan you are just increasing the height of the picture & moving the lines out of sight, above the tube height .. and in order to do that you are increasing slightly the distance between scanning lines.

I'll keep looking for the information that will maybe allow you to understand what is happening .. and I'll pot it here when I find it.


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## txe5502 (Apr 11, 2008)

Actually, when the distance between the lines is affected exactly opposite from what is expected. When I increase the vertical height, part of the top and bottom of the image goes off screen, but the lines get farther apart, and go farther down from the top, covering more of the picture, while decreasing vertical height places black bars at the top and bottom and squeezes the picture into a narrow area, but makes the horizontal lines go up farther, and recede from the image. This is the reason why I believe the cause is overscan, because the behavior of the lines is exactly opposite of the behavior of the top of the image, despite the lines being at the top.


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## Done_Fishin (Oct 10, 2006)

obviously being such an old set, it's possible that the capacitors around the vertical / horizontal deflection IC's might have lost either ESR or capacitance and could be responsible for your problem .. but like I said, the description you have given is very very similar to what i have seen here in Greece on many older TV's and at some point Manufacturers recommended what programme number one should use when watching input from any source other than an RF transmission. I am assuming that those locations( for want of a better word) had an extra Filter added either using firmware or electronically to reshape or remove unwanted information at the start of the scanning pulses 

if you'd like a more technical explanation of what goes on I found this 

http://catalogs.infocommiq.com/AVCAT/images/documents/pdfs/TT148 - 4053.pdf

unfortunately it gives little insight into the reason why using DVD's & VCR's lose sync after the blanking pulse .. I'll see if any of the guys in my TV repair group can remind me


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## pappa smurf (Apr 23, 2011)

Have you tried watching the dvd on channel 4 instead of 3 ?


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## Done_Fishin (Oct 10, 2006)

had 3 responses so far from my TV repair colleagues


1.


> what line drive/osc chip does it use?
> Usually the mod was simply to apply 12V to one of the ic pins.This modified the flywheel sync.Sets that were ok on last channel etc just switched the 12V on or off.


2.


> Basically its down to the fact that the sync generated from a video
> recorder is not to broadcast standard and results in the `cogging`
> effect on the top of the image. Manufacturers got round this by
> switching the time constants on a allocated channel (often 0 or AV) to
> compensate.



3.


> The mod was to increase the time constant as I remember, I used to have a list of mods for different models, it was a very common problem in the early days of vcr's, before the manufacturers started to have a specified channels set-up for vcr use.


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## txe5502 (Apr 11, 2008)

Ok, response 2 seems likely given the behavior I am seeing, however, I feel I need to provide a little bit more background information on my setup.

The DVD player has only A/V output, and I am using an RF Modulator to convert A/V to RF/Coax, then using a 75 ohm to 300 ohm adapter to connect the coax to the actual TV set. Something strange I have noticed is I have one other DVD player (I dont really use that one as it is an older model from the early 2000's and it cannot read double layer DVDs, which it seems most DVDs use this technology now), the other DVD player is a combo DVD/VHS player, VHS tapes play perfectly fine from that one using both A/V out through the RF Modulator AND the built in RF out on the combo DVD/VHS player, however, on the exact same player, DVDs show the exact same behavior as they do on the other, horizontal lines at the top of the screen that fade in and out as the DVD plays. One thing I havent thought about is that the DVD I am using to experiment with this problem is a widescreen 16:9 aspect DVD and the DVD menu of it is 4:3 standard, so it is possible that maybe DVD players are outputting widescreen DVDs with the number of lines designed for a widescreen TV rather than 4:3 standard, and maybe that is not syncing with my TV. I will have to find a 4:3 DVD that I can test this with, if a 4:3 DVD plays properly, then I will know that is the problem, but I am baffled as to how I can workaround it if this is the case.

Oh, and channel 3/4 doesn't make any difference, it's all the same, which I figured it would be, as this seems to be more related to sync/scan than carrier frequency.


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## Done_Fishin (Oct 10, 2006)

I'm still getting replies all along the same lines as before .. if you find a "normal" DVD (4:3) let me know how it behaves .. in the meantime I will try to track down a diagram or info about the IC being used for the scan on your set ..


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## txe5502 (Apr 11, 2008)

I do not believe there is any IC in my set, I have seen one identical apart before, and all I believe it has in it is capacitors, resistors, transistors, it is a 1970's model set. From what I saw, even the audio amplifier is entirely based on a board of transistors.


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## Done_Fishin (Oct 10, 2006)

That could make things a tad more difficult when trying to modify the circuitry, reminds me of an old Grundig B&W that I was repairing back in the early 90's ..


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## txe5502 (Apr 11, 2008)

New information I just discovered/noticed

The lines I see at the top of my screen only appear during movie playback, they do not appear at the FBI Warning screen, or on any of the DVD's menus, only during movie playback, and if I go back to the menu from playback, they disappear, it appears almost as if it is something that is being intentionally put there by the DVD it's self, but all DVDs do this. I have also noticed the lines fade out then back in again every 10 seconds, but disappear immediately without any fading if I return to the DVD menu.

Not sure what this could be, or why it would do that, but this could be some very vital information, as it may not be anything involving sync rate at all. A friend told me it may be some sort of copy protection thinking my RF modulator is a VCR, if that is the case, I am not sure what I should do about it. I wonder if it is possible to get another RF modulator that can handle a DVD player without causing this.


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## Done_Fishin (Oct 10, 2006)

doubt if it's the modulator most likely the way that the hardware / controller is handling the signals .. as for the start of the scan it contains information relevant to the possible device that it's being used with


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