RGB -> VGA - confused

johnk

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A query about VGA inputs on plasma screens.

As I understand it the HD-15 input accepts RGB-HV (i.e. separate horizonal and vertical sync) wheras most non-PC devices (DVD players etc) output RGB-Y (sync on composite). That's the full extent of my very iffy knowledge of this area.

Yet there seem to be plenty of RGB -> VGA cables out there that allow you, in theory, to connect your DVD player or whatever to the VGA input on your plasma (I'm not talking about converters such as the JS technology units, just straight, inexpensive cables). How do they work?

My specific reason for looking into this is that I'd like to connect my Pinnacle Showcenter to my LG (42PC1D) plasma's VGA input. The Showcenter has an option to output to a VGA monitor via the scart socket at a fixed 1024x768, 60Hz. Can I just buy a Scart to VGA cable to use this option? I did of course, contact Pinnacle support about what cable to buy, but couldn't get a sensible answer.

My plasma manual says the screen supports the following relevant VGA modes:
RGB[PC]: 1024x768, 48.363KHz horizontal, 60Hz vertical
RGB[DTV]: 1024x768, 45KHz horizontal, 60 Hz vertical
 
Can't actually answer your question, but many yrs ago when I were lad....... monitors could also sync on the Green signal, or use composite sync, which had H/V on the same wire.
 
Hi,

That's something I'd like to know too.

According to the instruction book for the Showcenter, Pinnacle listed an optional cable for this purpose but support denied all knowledge of it and said they didn't know if it was possible.

Silly me - they only designed the product :rotfl:

I really wanted to connect it direct to a PC LCD monitor without having to use a scaler.

Any info would be appreciated.
 
As a step towards solving this problem, I did buy a SCART to VGA cable (Hama make one). This claims to send RBG-Y to the VGA output. I don't know how, as I didn't think a VGA input could accept RGB-Y, but that mystery remains.

Anyway, the result was - nothing. No picture. Not a surprise, really, but narrows the search. I'm guessing that in VGA mode the Showcenter is outputting component via the SCART. But that's just a guess.

MartinFXDX, I had the same response from Pinnacle. I have replied to them to point out that the manual says the cable does exist, but I'm not hopeful of any sensible response.
 
johnk, your display device needs to be able to accept 15khz/50Hz scan rate at it's VGA input...it is not the connector that is the problem, it's the chipset...if it is not meant to deal with PAL's refresh/scan rate you will need a converter...most cheaper/non-HomeTheatre PJs can take 15khz/50Hz input via their VGA input since it is their only means of taking interlaced component video for cost/space reasons...making it take RGB interlaced signal thus is just a metter of simple matrix conversion which is only up to the manufacturer to choose to implement or not...hell, VGA system IS RGB...plasmas are different animals since they have separate component connectors and their VGA inputs are not absolutely required to take interlaced signal so it is very likely that most plasmas or LCDs will only take 30khz/60Hz non-interlaced...so it is not a sync or SCART-VGA cable's problem, from the specs you quoted it's your plasma's inability...

EDIT: Didn't notice the bit that you are trying to get non-interlaced res to work so sorry, but I'll let my post linger for others to take benefit...
 
The interlaced / non interlaced bit is only half the story.

The connector also needs to be able to cope with 'composite sync'. All Sanyo Z series projectors can cope with this as can Panasonic plasmas from the 8 series onwards. I'm sure other devices probably can too.

You need to make sure your cable is wired as follows:-

Source > Display

Red > Red
Green > Green
Blue > Blue
Composite > H-Sync

If that doesn't work for your device, try connecting composite to the V-Sync pin, or failing that, try connecting it to both pins.

On the Sanyo projectors, you need to select RGB (SCART) from the source selection menu. On the Panasonic Plasmas, you need to select the 'PC' input, then press the setup button and change Sync to 'Combined'.

Regards,

Steve
 
ALso noite that scart use a 15KHz horzontal sync signal (not comaptible with many monitors (VGA H sync is 30 KHz IIRC) also RGBcvS and RGBS are dfferent and often composite video isnt strong enough to sync an RGBS device designed for a dedicated sync this what a JS tech box does ots strips the guff out of the composite signal and amplifies it to give a stronger sync (actually RGBSS as its transmits the CS combined sync down both H and V lines)
 
John - you need to find out exactly what pins the showcenter will use on the scart output for RGBHV and then have a cable made up that connects said pins to the relevant ones on a d-sub head. Easy really!! Keene I think do custom cables, Van Damme do really nice ones.

As for the cables already on the market, these are generally wired for such devices as the Sanyo LCD projectors and are wire as RGBSync as commented above. But there's it always this danger with cables to try and match the types of plug at each end rather than to appreciate it's how they are wired under the hood and what signal they are carrying that is important!!
 
Thanks for all the posts.

My wish is to just attach a PC LCD monitor to the Showcenter which is also attached to a hifi systm.

I have just e mailed Pinnacle (again) about this and posted on their user forum.

I am ever the optimist:eek:

Will let you know if they are able to come up with the pin to pin information. I really can't see why they wouldn't be able to if they wanted!
 
Will let you know if they are able to come up with the pin to pin information. I really can't see why they wouldn't be able to if they wanted!

MartinFXDX - finally got a response from Pinnacle. No, despite offering a Scart to VGA option on the Showcenter, they don't do a cable for it :rolleyes: - however, they did send me a pin out, which I have attached.

Now I have never built a cable like this, and I'm no expert, so if anyone can offer guidance - such as... what exactly are we building here (as in "component to VGA" or "RGBY to VGA" or whatever) - and will it work on all plasma/LCD VGA inputs.
 

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Hi

It's a non standard cable designed to make use of a particular feature of the Showcenter.

You can't really give a name to it, nor would you be able to buy one off the shelf.

Best thing to do is get an old VGA cable and cut one end off and fit a SCART plug.

Regards,

Steve
 
It should work on any Plasma or LCD as it appears to have proper separate HSync and VSync connections.

From what you said earlier, the Showcenter is outputting 1024x768 non interlaced at 60Hz when you set that menu option.

I can't see any reason for it not to work.

Steve
 
Hi
Best thing to do is get an old VGA cable and cut one end off and fit a SCART plug.

Regards,

Steve

Steve - thanks for your response. I'm tempted to have a go, but I've never tried this kind of thing before. Hell, I've never even used a soldering iron (got as far as buying one - it's sitting in a shelf).

But given that the alternative would be an expensive custom-made cable, it's got to be worth a try.

John
 
I wouldn't necessarily recommend it but you don't actually need to solder SCART plugs. They are designed to have the connectors crimped on.

This does - however - make the soldering nice and easy as you can 'crimp' the pins onto the wires (just squeeze with some pliers) and then solder them all up afterwards in one go.

Where are you based? I'd be happy to make up the cable for you if you like...

Steve
 
Hi all,

I've been in touch with Keene and they said

"Hi, just had a quick read of the forum, it's a fairly common problem as there are a lot of scart to VGA cables all doing different things. It looks like the showcenter can give out RGB with H and V sync in which case you would need the SBB92H. This cable is wired exactly like the pin-out diagram shown on the av forum thread. We do lengths of 1m, 2m, 5m and 10m, although we can also make this to any length at an extra cost. We could also have it wired with audio coming out of the scart into a 3.5mm jack if that was required."

On looking at the rear of the SC however, I think (for the SC200 anyway) a straight entry SCART would be best. Keene can make this up and said-

"this would take 7-10 days to have made and would cost £34.50 as a base and £3.20 per meter."

The only thing worrying me about using this to connect direct to a PC LCD monitor is hornydragon's comment -

"ALso noite that scart use a 15KHz horzontal sync signal (not comaptible with many monitors (VGA H sync is 30 KHz IIRC) also RGBcvS and RGBS are dfferent and often composite video isnt strong enough to sync an RGBS device designed for a dedicated sync this what a JS tech box does ots strips the guff out of the composite signal and amplifies it to give a stronger sync (actually RGBSS as its transmits the CS combined sync down both H and V lines)"

Any views would be welcome.

Cheers
 
johnk, first exclude your plasma as the source of the problem: I think it is best to connect a laptop or a desktop computer to its VGA port and set it to output 1024*768 at 60Hz...if there is a picture, the problem then lies in either the cable or the Showcenter...
 
johnk, first exclude your plasma as the source of the problem: I think it is best to connect a laptop or a desktop computer to its VGA port and set it to output 1024*768 at 60Hz...

Kalos - thanks. Yes, I've attached my laptop at 1024*768/60Hz, and it works okay. I'm sure it's the cable. Steve has kindly said he will build me a cable to Pinnacle's spec. I'll report back...
 
ALso noite that scart use a 15KHz horzontal sync signal (not comaptible with many monitors (VGA H sync is 30 KHz IIRC) also RGBcvS and RGBS are dfferent and often composite video isnt strong enough to sync an RGBS device designed for a dedicated sync this what a JS tech box does ots strips the guff out of the composite signal and amplifies it to give a stronger sync (actually RGBSS as its transmits the CS combined sync down both H and V lines)
Scart is the connection, not the signal, if a scart is designed to give out rgb h & v then it's the same horizontal scan rate as a monitor. Keene's cable will work. cheers
 
Scart is the connection, not the signal, if a scart is designed to give out rgb h & v then it's the same horizontal scan rate as a monitor. Keene's cable will work. cheers

scart is the conenction and yes its just a cable but RGBcvS is pretty unique to scart devices scart cant carry RGBHV it only has 4 video cores (excluding Composite return) and it isnt same horzonatal scan as a monitor as it its a video signal not a PC sepc signal
 
Hi

The Showcenter is using pin 10 and 12 to transmit seperate TTL Hsync and Vsync signals though.

The *connector* is perfectly capable of carrying RGBHV, it's just down to how the manufacturer implements it.

In this case, they are using two otherwise unused pins. It's unlikely that this would ever cause a problem as presumably those two pins only output the TTL sync signal when VGA output has been selected on the unit.

Regards,

Steve
 
Hi

The Showcenter is using pin 10 and 12 to transmit seperate TTL Hsync and Vsync signals though.

The *connector* is perfectly capable of carrying RGBHV, it's just down to how the manufacturer implements it.

In this case, they are using two otherwise unused pins. It's unlikely that this would ever cause a problem as presumably those two pins only output the TTL sync signal when VGA output has been selected on the unit.

Regards,

Steve

interesting (not part of the Peritel AV connector spec) I forget we were talking about a show centre rather than an RGB device (RGBcvS) My comments on 15Khz sync are part of the spec for RGBcvS which this isnt so it should work (why the hell they used scart for this they only know but a D-Sub on the rear would have been much better)
 
exactly, it's easier than designing they're own connection and people will go to them for the cable, which would usually be expensive. There are a few products that use the scart for RGB h and V for various reasons. Pin 10 and 12 are the dedicated pins for h and v sync, always have been.
 

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