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Discussion Starter · #1 ·
Build you own S-Video Lock Block!


Here's what you'll need:

S-Video socket,

S-Vidoe plug,

Cable,

Two 220uF Electrolytic capacitors.


In the UK see Maplin.co.uk,

In the US see Radio Shack.


Any TV engineer should be able to build this quite easily if you can't DIY.


Each connector viewed from the back, there is no cross-over required and each cable goes to it's respective pin on the other connector. The capacitors should be 220uF or higher, and the negative terminal goes to the plasma screen.


I suggest keeping the lead lenths short and using 75ohm co-ax. I also suggest that this be an adaptor that you place at your screen rather than souce.


All the best,


Dr John Sim.
J.S. Technology
 

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Discussion Starter · #3 ·
Quote:
Originally posted by Will Kronos CDn
May I ask, What is a "SVHS Lock Block"?

seems like a DC decoupler to me.
S-VHS is a tape standard, I think you mean S-Video.


Yes, DC block. Hence the name of Lock Block :) . But it will allow you to get your zoom modes back on your Panasonic screen if you're affected by this problem - without taking any video boards out to snip components. Now, this had got to be a good idea!


All the best,


Dr John Sim.
J.S. Technology :)
 

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Many thanks to you Dr. John Sim!


I just received my 42" 42PWD4UY last week only to find that it locks aspect when plugged into my DirecTV silver edition receiver via S Video. The last thing I want to do at this stage is snip a resister on my $5K plasma and I'm not excited about sending the board in to have it altered under warranty (I want to check for the VGA bug before I consider trying a board swap - I'll keep mine for sure if the VGA interface works with HDTV sources).


If the Denon 3802 AV Receiver does not solve this problem I will most certainly build this adapter and put it to work in my home theater.


Bravo! Great forum.


_Kale
 

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Many thanks for working this out. I wasn't afraid to snip a resistor, but pulling the panel down off the wall mount to do so was going to be a severe marriage-tester.
 

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Dr. John -


Thanks again for doing the groundwork on this. I just built this little goodie and it works exactly as advertised, allowing me to run my ancient laser player through the superior composite-to-S-video converter in my Onkyo receiver without locking up in zoom.


For various reasons, I decided to try it first at the receiver end rather than at the plasma input. Looking onto about 10 ft of high quality video co-ax (about the size of RG-6, purchased from MarkerTek) it worked just fine with no loss of resolution or Y-C issues - checked with Avia. You just have to reverse the polarity of the caps relative to the famale & male plugs.
 

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Discussion Starter · #7 ·
It's a very simple circuit, but just watch you get the capacitors round the right way! I've not done it myself, but there's many stories about electrolytic capcitors exploding.....


All the best,


Dr John Sim.
J.S. Technology.


PS - Incandescent with rage at Royal Bank of Scotland VISA for charging interest as they take six days to process payments from the Royal Bank of Scotland.
 

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Discussion Starter · #9 ·
Quote:
Originally posted by IUnknown
I decided to go find the thread rather than to ask answered questions. For any of you (like me) that haven't been following this closely, here is the background thread. Hummmmmmm, Has promises from some Symanski guy to build an external circuit. Looks like video lock is a "feature".

http://www.avsforum.com/avs-vb/showt...ght=video+lock
I wonder if that Symanski guy ever came up with the solution... Tonge firmly in cheek!


I said I'd do it, I knew it would stop the DC offset, but also wanted to ensure it wasn't Line 23 (the data burst) that was the route of the problem. More importantly, I also wanted to ensure that it didn't affect the picture quality, which it doesn't.


All the best,


Dr John Sim.
J.S. Technology
 

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I'd be interested in seeing a picture or two to show how people have physically put this together. I'd imagine it'd be nice to somehow wrap it in a shielded box or metal tube.


--Karl
 

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Dr. Sim - thanks for working this out and for posting your solution. I am one of the unlucky ones that has the SVideo locking problem (just received the plasma last night).


I currently have a 5m SVideo cable that I purchased from bettercables.com. If I am going to perform this fix myself, can I use the existing cable and just "splice" the capacitors into the cable? I realize that the negative terminals are suppossed to go into the plasma. However, does the positioning of the capacitors along the length of the cable matter (e.g. closer to the plasma or closer to the source)?
 

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Radio Shack lists two different 220uF Electrolytic capacitors. They are:


220µF 35V 20% Axial-Lead Electrolytic Capacitor

220µF 35V 20% Radial-lead Electrolytic Capacitor


Does anyone know which ones should I use to make the modification to my SVideo cable? Thanks yet again.
 

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The only difference between those two are where the leads come out, otherwise they are the same. However that is much larger than required, you probably only need a capacitor rated at 4V, so 35V is overkill and its much larger size. You could also use a larger value than 220uF, but lower voltage there might be one thats smaller size. I think 100uF will work too. The axial type would be the best shape for an in-line cable, it could be covered with black electrical tape at the end. By the way in San Diego, you can go to Fry's Electronics or Gateway Electronics in Kearny Mesa - they have a wider selection of values and sizes for electrolytic and tantalum capacitors and may be cheaper as well than Radio Shack.
 

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Don, thanks for the reply and advice, both in this thread and the other I posted. I am going to try to get in touch with Panasonic today. I will let everyone know what I find out (I will also ask if this is a problem in the 5U models). I am still not sure if I am going the S-Video modification route, or an attempt to get Panasonic to fix the problem.
 

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Discussion Starter · #17 ·
Hi,


don't splice in to a bettercables.com cable - do an additional external modification! I've got too much respect for their cables to see them chopped up!


I only built one of the S-Video lock-block circuits, and gave it away to a person with the problem. So at the moment I can't take any photos of it. I guess it wouldn't be too difficult to build another.


Ofer:

RGB to Component (YUV) product is in prodcution. I've been very busy with the RGB to Plasma VGA unit, which has delayed the component converter. However, the component converter will be available soon.


DonBerg:

I didn't try any other size of capacitor as I know the 220uF works. As for radial/axial, that's just where the leads come out - again nothing to worry about.


If you really really need a lead built, I could be talked into building more!


All the best,


Dr John Sim.
J.S. Technology
 

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I was just about to solder the DC block circuit into a spare S-Video cable when I thought I would try and see if my receiver would block the DC signal when it is used as a switch. Sure enough, if I route the S-video signal through my receiver (4 year old Pioneer Elite model with THX and DD) then to the Panny 4U, I am able to switch aspect ratios. Very cool and no need to kludge together a simple circuit.


For those who do not wish to deal with soldering, heat shrink tubing and assembling the simple DC block circuit, I recommend using the reciever as a switcher.


I'm not sure how much video bandwidth I am loosing with the extra cabling and going through the receiver, but I do not notice any more artifacts compared to before. (from Direct TV source)
 

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S-video and composite are so low bandwidth (6Mhz) you probably will never lose any significant bandwidth thru the receiver switcher. Its only a concern on the high bandwidth HD component video signal which requires 37Mhz. As you found out, most video switchers will AC-couple the signal, which is what the DC block circuit is doing with the capacitor.
 
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