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Author Topic: How to use SCART for our hobby  (Read 124713 times)

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Level42

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How to use SCART for our hobby
« on: March 03, 2008, 04:27:06 pm »
I've seen more and more questions about how to use the SCART connector that is present on all European TV's in relation to our hobby.

This posting is a try to answer all these questions for once and for all. I bet I'll fail, but it's worth the try :)

What is SCART ?

Not the official text but here goes:
SCART is a connector that was designed by the French. In a short moment of brilliance, the government in France made it mandatory for every TV set sold there to have the SCART connector. This sort of forced all big TV makers to include a SCART connector on every TV that was shipped to Europe (or built there).

SCART is NOT (I REPEAT: NOT) a definition of signals.

Instead it bundles a range of analog signals that are (were) commonly used in relation to TV's in ONE standardized connector.

SCART usually incorporates the following video signals:
1) Composite video
2) S-video
3) RGB video

I say usually because not all devices support all signals. F.I., a VHS videorecorder, by nature, does not support RGB signals. That is because the video is recorded on the tape with a signal that is simular to composite video.

Every TV however, should have at least one SCART connector that allows input of any of these signals.

(SCART also supports audio signals of course, but I leave them out of this thread, because they will be rarely used in our hobby, most people connect speakers to the PC running Mame, or in original cabs, the installed audio amplifier and speakers are used).


What is RGB video ?

RGB video is the most basic form of video signal you can have in relation to CRT driven color TV's. There are separate wires for each basic color Red Green and Blue, and one for the sync signal. Because of this, none of the signals can influence each-other. In good quality SCART cables, every signal line has it's own shield (return or ground)to further prevent cross-talk between them and other wires.

Every color TV in the world is decoding whatever signal (HF through Antenna, composite video etc.) is input to it into this basic RGB signal, before it feeds it to the CRT. So, if we use the RGB signal on the SCART connector ALL the decoding electronics in the TV are by-passed, ensuring the best possible picture quality. By doing this we use the TV exactly like a "real" arcade/open frame monitor.
There is NO quality difference in picture between a "real" arcade monitor or a TV that is used with RGB.

How about the other signals ?
Well, first there was Composite video. The one (and only) advantage of this signal is that you can transport it through a single wire (and a shield). To make this work, all the color info AND sync info is combined into one signal. The TV will have to decode this signal into all the seperate colors and sync again. This process causes a significant loss in picture quality. Composite video is NOT recommended to be used for our hobby because of this.

Then there's S-video. With S-video you have one wire for the sync, and one wire for ALL the colors. So the colors are still combined. This still requires decoding in the TV, and still introduces a reduction in quality. Outside of Europe, this is often used in our hobby, because only European TV's have SCART.
I would not recommend it, because RGB is the best option to choose, and it's present out the outputs of your PC or original game PCB.

OK,OK, I've read all the theory, I want to know how to use it !

Yeah, yeah, it can't hurt to have a little theory to understand what we're using.

OK, now, almost all PC's have a RGB - VGA output.  So, it should be easy connect it to a SCART connector, right ?
Right ! Well, the physical connection is easy. However, a VGA card outputs video at much higher frequencies than a TV can handle. In our hobby, most often, we want to use 15 kHz output, as the vast majority of (classic) arcade games use(d) this frequency.

There are two main ways to get 15 kHz out of your computer:
1) Get the Ultimarc ArcadeVGA card. Basicaly, this is a normal VGA card, but it has an "adapted" BIOS that will allow the card to only run in 15 kHZ. So from the first start-up, you will see everything incl. the boot-up screens
2) Use a software tool like http://forum.arcadecontrols.com/index.php?topic=66402.0 This will let the output of a regular VGA card run in 15 kHz.

So, when we have eiter up and running OR we are using an original arcade game PCB that's running 15 kHz ( the vast majority of the classics), we are ready to wire it up !

First PC to SCART:




When we look at the picture it's simple to see that each color has it's own wire AND return.
This is also true for the sync signal (Do not confuse composite sync with composite video. Composite sync is quite simply the horizontal and vertical sync signals combined. There is NO quality difference in using separate or composite SYNC signals).

So, you think you're ready ? No.

We have to "tell" the SCART connector that we are inputting an external video signal to it and that the TV should select the AV-mode. This is a great feature of SCART, because without adjusting your TV, you can have external devices automatically select the right setting. Some TV's even come out of stand-by mode when this signal is first applied....

We can do this by supplying a Voltage between 9,5V and 12V to pin 8. Since computers have plenty of 12V outputs, and the same applies for most of the original arcade PCB's, it's easy to connect a +12V lead to pin 8.

Now, we have selected the AV-mode but we also have to "tell" the TV what kind of video signal we are supplying.  This can be done by providing a voltage between 1V and 3V.
Now, that are voltages that we don't find (easily) on PC's or original arcade PCB's. However it's very easy to do it. We take a +5V supply (easy on PC connectors, red wire) and put a resistor in series with the +5V supply. This will lower the voltage to about 2V.

(Note: In the past I've uploaded a schematic on this forum in various threads from my good friend Darthnuno. This does not show the 100 Ohms resistor. On some TV's this still works. However, I've encountered a more recent TV and on this I could not get the TV to work, the cause was this missing resistor.... so stay in spec and use the resistor !!!!)


This schematic shows how to hook up both votages from a standard PC connector. On an original arcade PCB, you will need to find a +12V and +5V point yourself, which shouldn't be that hard, often there are test-points where you can pick it up from....



The included pictures are from:

http://www.idiots.org.uk/vga_rgb_scart

saint's edit -- made images local to BYOAC
« Last Edit: March 10, 2008, 08:00:13 pm by saint »

grantspain

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Re: How to use SCART for our hobby
« Reply #1 on: March 03, 2008, 06:18:40 pm »
good stuff :cheers:

Mr Wilson

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Re: How to use SCART for our hobby
« Reply #2 on: March 08, 2008, 07:04:39 am »
i'm using a s-video to scart at the mo its a all in one not one with a scart block can i force this to go to av1  by putting 12v on pin 8 of the scart?

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Re: How to use SCART for our hobby
« Reply #3 on: March 08, 2008, 04:35:49 pm »
I don't think so.

This is quoted from wikipedia:

There is no switching signal to indicate S-Video. Some TVs can auto-detect the presence of the S-Video signal but more commonly the S-Video input needs to be manually selected.

....


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Re: How to use SCART for our hobby
« Reply #4 on: March 09, 2008, 03:25:15 pm »
i've improved my soldering skills and made it now ;D i've just got to  get a 100 ohms resistor tomorrow can you still use your front end if its running at 15khz?

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Re: How to use SCART for our hobby
« Reply #5 on: March 09, 2008, 04:36:47 pm »
try'd the lead with no power to it,just to see if it worked and got nothing except  sound turned off pc connected s-video back up turned it on and i only get the boot up screen then it goes blank tried vga to old monitor same thing have i f*cked up my graphics card??? :angry:

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Re: How to use SCART for our hobby
« Reply #6 on: March 09, 2008, 07:26:26 pm »
Have you tried booting to safe mode by pressing F8 during boot just to rule out a software problem? Oh and do you have to run at 15khz to use this cable?

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Re: How to use SCART for our hobby
« Reply #7 on: March 10, 2008, 03:52:34 pm »
Yes If you see the boot-up screen it sounds to me like you're not running a tool like Soft-15kHz (http://forum.arcadecontrols.com/index.php?topic=66402.0) to have the VGA card run at 15 kHz. If you're not using this (or an ArcadeVGA card) the TV will probably shut down to protect itself because it detects out of spec (too high) syncing frequencies.

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Re: How to use SCART for our hobby
« Reply #8 on: March 10, 2008, 07:46:34 pm »
This is a great guide and should be stickied (or at least added to the wiki)!   :cheers:
It also makes me mad that US televisions don't have an SCART port.  :hissy:

Level42

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Re: How to use SCART for our hobby
« Reply #9 on: March 14, 2008, 07:11:54 am »
This is a great guide and should be stickied (or at least added to the wiki)!   :cheers:
It also makes me mad that US televisions don't have an SCART port.  :hissy:

Thanks, and indeed, you should be angry.....:D
On the other hand, this single advantage that we have overhere never will outweigh all the advantages that you guys in the US have in this hobby...

I'm always prepared to ship a European TV with SCART (and I'l MAKE the cable for you) if you ship me back a nice Ms.Pac Man upright :D
« Last Edit: March 14, 2008, 07:13:39 am by Level42 »

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Re: How to use SCART for our hobby
« Reply #10 on: April 07, 2008, 02:26:46 pm »
Geeez.....was working on my Centipede the other day and suddenly realised that I hadn't included the resistors in the RGB lines when you use the schematics.

The thing is, that real Arcade PCBs deliver a TTL level video signal. This can be 5Vtt. A VGA card, will only supply 1V.  Following this, you can use the schematics like indicated with a PC (VGA) connection.

However, if you want to connect a real arcade PCB (OR f.i. a J-Pac) you will need to add a resistor in series with each color signal. I've found 150 Ohms to be a good value.

I will try to re-write everything to make it clear what to do for PC versus arcade PCB situations....but I'm limited in time this week....

Zebidee

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Re: How to use SCART for our hobby
« Reply #11 on: April 11, 2008, 04:56:03 am »
I've done countless VGA-SCART conversions for TVs. 

This includes a couple of JAMMA-SCART setups for arcade cabs, to allow you to take the PC/JPAC out and plug a JAMMA PCB in. The monitors I used were Sony professional video monitors ("broadcast" monitors, used in TV studios).  If you want to do this, you will need to use resistors on the RGB signals (but not the sync).

I tested a few different resistor values, and found that 75ohms seemed to work the best in this instance.  100ohm resistors work fine as well, but the colours were slightly duller (but acceptable).  75ohm resistors gave superior results.  The clients that ended up with these systems were both very happy.

For comparison, I also had another cab running with one of these Sony monitors, but with a straight VGA-SCART cable.

I tested these JAMMA-SCART systems using video output from a JPAC, which boosts the video signals to levels appropriate for an arcade monitor.  In fact, the RGB signals were normally around 1.2-2v from the JPAC (not 5v), but under 1v after applying resistors.

Sync signals from the JPAC came through at about 3.3-3.5v, and there was no need to put a resistor on this signal line (I tried, but it gave inferior results, such as poor sync at the top of the screen).  Note that actual arcade PCB voltages may vary somewhat.

Regarding the 5v input to pin 16 for RGB-AV switching - TVs vary with their need for this.  Mostly, I've done it by just running a short wire from pin 20 (ie sync) to pin 16, and this has worked fine.  I'd recommend to people that they try this method first, because it is much simpler.  However, some TVs are a bit fussier, and I've had to run a separate 5v signal with a resistor on it (much as you've shown in your diagram).  The reason (I believe) is that the sync signal voltage will actually vary a bit, and this variation is unacceptable for certain TVs.  The brands I've needed to do this with tended to be TEAC TVs in particular, although you may find that other individual TVs of any brand may require this.  However, I've never encountered the need to run a separate 5v signal to pin 16 for any LOEWE, SONY or PHILLIPS SCART TVs.  It seems that the better quality TVs are more forgiving.

Regarding the need for a 12v signal to pin 8, there is no consistency here.  I once had a Phillips 29" TV, dead from the dump with failed tuner, but it worked fine as an arcade monitor once I hooked up a cable with a 12v switching signal.  once again, TEAC TVs tend to require this 12v switching signal.  As you can probably guess, I try to avoid TEAC TVs nowadays.  They are a poorer-quality brand anyway.

I apologise for the long post.  I should probably write this up somewhere in a more structured way ....

Zeb.
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Re: How to use SCART for our hobby
« Reply #12 on: April 15, 2008, 01:22:59 pm »
I tried to stick to the standards as they were defined. This because it will work for everyone. I know some TV's accept 5V instead of 3,5 V. But because I wasn't aware of it, I lost a couple of hours on finding out why my next TV I worked on (Which was newer) DIDN"T work....

So, stick to the standards, and you'll be 100% sure it works.
 

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Re: How to use SCART for our hobby
« Reply #13 on: April 15, 2008, 05:09:17 pm »
Hi I'm new here and trying to build my first MAME cabinet.

I'm in Australia and fluked getting a TV with a SCART connector. After reading this I consider myself very lucky. I'm trying to make a VGA-SCART cable but am wondering about the SCART pin 21. Where does it get wired to? It says ground so is jumping it accross to pin 18 (0v) an acceptable alternative?

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Re: How to use SCART for our hobby
« Reply #14 on: April 16, 2008, 04:26:53 am »
Pin 21 is simply the outer shield of the cable and connector. It's the metal edge of the connector.
The purpose is to shield of any signals from outside the cable to interfere.

So far, I haven't bothered to connect it. (Classic) arcade video signals were low-res and cab builders didn't do any shielding of the wires etc. So there's no real need to do it now.

Since you're making VGA to SCART, you could connect the outer shield of the VGA cable to it. Won't harm.
« Last Edit: April 16, 2008, 04:29:26 am by Level42 »

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Re: How to use SCART for our hobby
« Reply #15 on: April 16, 2008, 07:45:13 am »
So, stick to the standards, and you'll be 100% sure it works.
 

Agreed.  However, given the extra difficulty and complication of adding power supply from a molex connector, I would still suggest that one tries doing it by just jumping a wire from pin 20 to pin 16 first.  Modify the cable if it doesn't work after that.

I actually keep two types of VGA-SCART cable on hand for testing newly acquired TVs - one with the 5v & 12v power supply via molex connector, and one without.

To put this another way, I've quoted people $40 to make the simple cable and $60 for the complex (or 100%) version, reflecting the extra costs & time (these are bargain basement rates for "mame-brothers", esp. considering the time involved). In most cases, one only needs the simple version.

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Re: How to use SCART for our hobby
« Reply #16 on: April 19, 2008, 07:29:02 am »
I'd like to point out that this cable only works if the card outputs COMPOSITE Sync.
If it doesn't (like with Soft-15kHz) you'll need to connect VGA Pin 13 and VGA Pin 14 to SCART Pin 20.
I do all that stuff even without a Joystick ;)
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Re: How to use SCART for our hobby
« Reply #17 on: April 20, 2008, 07:39:41 pm »
I'd like to point out that this cable only works if the card outputs COMPOSITE Sync.
If it doesn't (like with Soft-15kHz) you'll need to connect VGA Pin 13 and VGA Pin 14 to SCART Pin 20.

Good point, SailorSat!

Note that if the video card outputs negative sync on both horizontal & vertical (H&V), then you won't have any problems with just twisting the wires from VGA pins 13 & 14 together and connecting them to SCART pin 20 to make the cable.  Every ATI-based card I've used outputs negative on both VGA 13 & 14.

The ArcadeVGA cards work this way - just twist the wires together and you'll be fine.

However, if your card outputs some combination of positive and negative sync then you could have a problem.  NVidia cards seem to allow you to change the sync polarity,  so it is worthwhile checking this for your particular card.  Make both H&V negative if possible.
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Re: How to use SCART for our hobby
« Reply #18 on: April 20, 2008, 09:00:52 pm »
Both ATI and NVIDIA can be configured, so that shouldn't be a problem.
Also in Soft-15kHz all syncs are negative.
I do all that stuff even without a Joystick ;)
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Re: How to use SCART for our hobby
« Reply #19 on: April 22, 2008, 11:31:02 pm »
Hey guys,

I'm in Australia too and when I bought the TV for my cabinet in 2001 I did a lot of research to try and find a TV with SCART.. now I'm not sure if what I was told is true or if it was and has sinced changed but...

I was told by a number of retailers including specialist importers that almost every TV in Australia - that isn't imported from Europe - with SCART doesn't actually have true RGB, the RGB pins are just hooked up to the composite (or maybe s-video) input. This is due to the TVs all being manufactured in the same factory but then shipped off to different places; so for Australia they use the casing for all over the world but just put in a dodgy SCART port that is really no more than composite or s-video.

For this reason I just went for the S-Video... Although the TV I bought had SCART as well (I say had as I blew it up shortly after putting it in the cabinet! Now I just have a TV with s-video and composite  :banghead: )

Can anyone confirm this?

Mr Kray

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Re: How to use SCART for our hobby
« Reply #20 on: April 28, 2008, 06:58:50 am »
RGB and S-Video shares the pinout the tv determines  if you are using RGB by the voltage that the SCART receive on a specific pin (the one in the schematics for the cable).

from wikipedia:

"Two pins provide switching signals.

Pin 8, the switch signal pin, carries a low frequency (less than 50 Hz) signal from the source that indicates the type of video present.

0 V2 V means no signal, or internal bypass
4.5 V7 V (nominal 6 V) means a widescreen (16:9) signal
9.5 V12 V (nominal 12 V) means a normal (4:3) signal
Pin 16, the blanking signal pin, carries a signal from the source that indicates that the signal is either RGB or composite.

0 V0.4 V means composite.
1 V3 V (nominal 1 V) means RGB only.
The original specification defined pin 16 as a high frequency (up to 3 MHz) signal that blanked the composite video. The RGB inputs were always active and the signal 'punches holes' in the composite video. This could be used to overlay subtitles from an external Teletext decoder.

0 V0.4 V means composite with a transparent RGB overlay.
1 V3 V (nominal 1 V) RGB only.
There is no switching signal to indicate S-Video. Some TVs can auto-detect the presence of the S-Video signal but more commonly the S-Video input needs to be manually selected.

"

I suggest to use a 1.5v battery instead of the PC psu for RGB blanking.
« Last Edit: April 28, 2008, 07:08:23 am by Bluedeath »
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Re: How to use SCART for our hobby
« Reply #21 on: April 28, 2008, 01:52:11 pm »
I was told by a number of retailers including specialist importers that almost every TV in Australia - that isn't imported from Europe - with SCART doesn't actually have true RGB, the RGB pins are just hooked up to the composite (or maybe s-video) input. This is due to the TVs all being manufactured in the same factory but then shipped off to different places; so for Australia they use the casing for all over the world but just put in a dodgy SCART port that is really no more than composite or s-video.
Mr Kray

I can confirm that this story put-up by retailers is a lie - mostly.

I have run RGB through SCART to countless TVs in Australia.  In just one case was the SCART input only good for composite (ie not RGB).  That was a mega-cheap "Goldstar" brand TV.  Goldstar always was a cheap brand, and this experience confirmed that fact.

Regarding s-video through SCART - usually TVs that accept s-video through SCART have multiple SCART ports, with one dedicated to s-video.

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Re: How to use SCART for our hobby
« Reply #22 on: May 22, 2008, 01:41:55 pm »
So can u wire the scart plug up, so it can turn any TV set on when you power up the PC??

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Re: How to use SCART for our hobby
« Reply #23 on: May 22, 2008, 08:31:53 pm »
No
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Re: How to use SCART for our hobby
« Reply #24 on: May 23, 2008, 04:38:21 am »
So can u wire the scart plug up, so it can turn any TV set on when you power up the PC??
If you want to turn on the monitor with the rest of your cab simply put the mains connection of the TV behind the mains switch of your cab. I do it all the time. Then, because of the SCART selecting signals the TV will immediately switch to the SCART input.

Also there ARE TV's that will switch from stand-by to operating by these signals, but not all of them.
« Last Edit: May 23, 2008, 04:40:34 am by Level42 »

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Re: How to use SCART for our hobby
« Reply #25 on: May 23, 2008, 05:42:46 am »
The Toshiba Tv im using only goes into standby when you turn it on via the plug

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Re: How to use SCART for our hobby
« Reply #26 on: May 23, 2008, 06:44:56 am »
The Toshiba Tv im using only goes into standby when you turn it on via the plug

OK, sorry for my short response earlier, but strictly speaking NO is the correct answer to your original question.  Single power switches for cabs are covered in many other threads on this forum and there are several different approaches, for which a dual-post single-throw switch (as Level42 suggests) is a possible option in some cases. However, I won't go into that here.

Get ready for a long post here - sorry.

Different TVs are, well, different.  So you have to work out what works for your TV .... which is easier said than done.  Here are some things to try.

1) If you can figure out how to access the service mode of your TV, you *might* be able to set it so that it can automatically come on when you apply power.  Service mode, as the name suggests, is designed so that only technicians can get to it.  Generally you need the original remote, and instructions from the service manual (the one techs get, NOT the user manual supplied with the TV).  To further complicate this, service manuals are generally not made available publicly, only to registered techs.  The reason for this is because you can completely screw the TV up through making wrong settings in the service mode, so be careful.

2) If you have the remote, try turning the TV off with the remote and then cycling the power off/on.  Then, when you turn it on, it might come on 'fully' (if you are lucky).  Some variation of this theme might work for your TV.

3) Some SCART TVs will come on into AUX mode if you have 12v applied to pin 8 (as Level42 suggests). 

4) If all else fails, you should be able to get the TV to come out of standby by pressing a channel button and/or the AUX button (perhaps labelled TV/AV).  A pain in the bum if you want to have a single power switch for your cab, but there you go.  If this is the case, and you are handy with a soldering iron, you could connect the button up to a momentary switch (eg standard arcade button) near your power switch, and press it just after you apply power to the cab.

Some power switches (including most standard TV power-on switches) include both a momentary switch (for signal voltages) as well as an always-on switch (for the mains voltage).  If you rig up an external power switch to your cab using one of these combined switches, then you *might* be able to use it to send a momentary signal through to your channel and/or AV button as you power the cab on.  I say *might* because you may actually have to wait for a second or two for the TV to power on before sending through the momentary signal to switch channel/AV mode, in which case you'll have to find another solution, perhaps involving a small capacitor (takes time to build up charge and therefore creates a delay before passing voltage through) or a relay.

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lettuce

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Re: How to use SCART for our hobby
« Reply #27 on: May 23, 2008, 01:02:39 pm »
Thanks for the indepth info. I do have the service code for the service menu, but i dont recall seeing anything to do with 'auto power on' etc. I have one of those power safe power strips, so when i turn the PC on it powers up all the other compliances that are connect to the power strip. as said when using this it just puts the TV into standby and not actually turn it on, but it does automatically go to the AUX channel which is a help. Is their a chance of blowing my TV up if i do try connecting a 12v current to pin 8 on the scart plug?

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Re: How to use SCART for our hobby
« Reply #28 on: May 23, 2008, 09:16:59 pm »
Is their a chance of blowing my TV up if i do try connecting a 12v current to pin 8 on the scart plug?

No - it is designed for this.  But you should also ground the 12v to pin 18, as shown in the diagram Level42's original post.

... it does automatically go to the AUX channel which is a help. 

However, it looks like you don't actually need to bother with it.
« Last Edit: May 23, 2008, 09:19:41 pm by Zebidee »
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lettuce

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Re: How to use SCART for our hobby
« Reply #29 on: May 24, 2008, 02:58:23 pm »
Hmm, just took my scartlead apart ( i didnt mod it, i bought it) and pin 8 on the scart plug seems to be already soldered up to a yellow wire from the vga plug, which also has a resistor soldered from pin 8 to pin 16??. Does this mean its already having a 12volt supply to pin 8??
« Last Edit: May 24, 2008, 03:10:38 pm by lettuce »

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Re: How to use SCART for our hobby
« Reply #30 on: May 24, 2008, 09:38:38 pm »
Lettuce, your cable must be relying on voltage from the VGA head on the video card.  It could only possibly be supplying 5v to SCART pin 8 as the VGA head doesn't output 12v.  Some VGA heads output 5v on pin 9.

ArcadeVGA cards put 5v to VGA pin 9, but I can't be sure of other manufacturers.  Many of the VGA cables I've seen, perhaps most of them, don't even both with a pin 9.  What video card do you use?

Depending upon your TV, 5v may be sufficient to trigger switching to AUX mode.  Technically 5v signals AUX modein 16:9, but if your TV doesn't do that then it probably will simply signal AUX mode.

Does your cable actually work?  I mean, so you get a PC picture on your Toshiba at all with this?

Also, as a BTW question - does this cable have an audio input plug to connect to your PC as well?  I ask this because the audio pins are wired up.
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lettuce

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Re: How to use SCART for our hobby
« Reply #31 on: May 25, 2008, 06:45:24 am »
Many of the VGA cables I've seen, perhaps most of them, don't even both with a pin 9.  What video card do you use?
Im using a ArcadeVGA APG card :)

Depending upon your TV, 5v may be sufficient to trigger switching to AUX mode.  Technically 5v signals AUX modein 16:9, but if your TV doesn't do that then it probably will simply signal AUX mode.
The TV im using it a, Toshiba 28N33B, its not a widescreen set just 4:3. Ive looked on the ulitmarc site and says pin 9 does indeed give a 5volt current (im guessing pin 9 on the VGA end?), im guess as you said its why my TV switches to the AUX channel when turned out from standby

Does your cable actually work?  I mean, so you get a PC picture on your Toshiba at all with this?
When i first got it and tried it out the screen on the TV kept rolling so i had to resolder a wire i believe to stop this from happen, but i cant 100% remember as it was over 2 years ago. I did try it on another TV but i just got a black screen for some reason!? Just interested  , why did you ask if the cable actually works?

Also, as a BTW question - does this cable have an audio input plug to connect to your PC as well?  I ask this because the audio pins are wired up.
Yeah it does, but i never use them as im not getting sound form the TV itself


This from the Ultimarc site

"IMPORTANT: Our ArcadeVGA card outputs 5 volts on pin 9. If this pin is routed through your cable, make sure to insulate any cut wire to prevent shorting.
Be doubly sure about grounding whenever connecting monitors. Check the continuity with an ohm-meter of the monitor chassis to power-cord ground BEFORE connecting anything else up. Also double-check the isolating transformer is still connected (see below)."

So im guessing the cable i have is wired up to pin 9 on the vga end, im understand from reading the above that i dont need to have this pin 9 wired up to get a display??
« Last Edit: May 25, 2008, 06:52:35 am by lettuce »

Zebidee

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Re: How to use SCART for our hobby
« Reply #32 on: May 25, 2008, 03:45:31 pm »
pin 9 does indeed give a 5volt current (im guessing pin 9 on the VGA end?), im guess as you said its why my TV switches to the AUX channel when turned out from standby[/b]

Your TV may well switch to Aux mode anyway, even without the 5v signal.

When i first got it and tried it out the screen on the TV kept rolling so i had to resolder a wire i believe to stop this from happen, but i cant 100% remember as it was over 2 years ago. I did try it on another TV but i just got a black screen for some reason!? Just interested  , why did you ask if the cable actually works?

Two years ago, it might have been that you had to connect VGA pins 13 & 14 together to get the VSYNC input to stop the rolling. 

Could be any number of reasons why the cable didn't work with your other TV.

The reason why I asked about whether the cable works is because if your videocard doesn't output 5v on VGA pin 9, then your cable WOULD NOT WORK.

Your experience with the other TV is interesting.  I've wired up cables before with 5v -> SCART pin 8 -> 16 that have NOT WORKED on certain TVs.

As noted earler, I have a lot of success simply bridging SCART pin 20 (sync) -> SCART pin 16, and doing away with the 5v to pin 8 and the resistor bridge from pin 8 -> resistor -> 16 altogether.  Simpler, neater, works (most of the time).

So im guessing the cable i have is wired up to pin 9 on the vga end, im understand from reading the above that i dont need to have this pin 9 wired up to get a display??

For the way your cable is currently wired, you definitely need 5v from VGA pin 9.  However, you might be able to do away with it and bridge SCART pin 20 -> pin 16 instead (as discussed earlier in this thread).

Rather than hacking up your existing cable, I suggest that you make a new cable without the SCART pin 8 hooked to 5v, but with a bridged SCART 20 -> 16 instead and and try that.  Mostly, the latter version works better.  Personally, I have both types of cable on hand for testing new SCART TVs with.  Occasionally I even need to try a cable that has both 5v -> SCART pin8 and a SCART 20 -> 16 bridge, but that is pretty rare.
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Re: How to use SCART for our hobby
« Reply #33 on: June 05, 2008, 07:18:45 pm »
hi

im inn the uk and im going to have a go at building a scart for my soft15hz card, it wont be in a cab its a media pc i want to use as a mame console if you like, can i get away with not supplying any voltages if i manualy select av with my remote?  also isit  ok to just twist the wires togeter because im not good at soldering. lol

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Re: How to use SCART for our hobby
« Reply #34 on: June 06, 2008, 07:02:37 am »
can i get away with not supplying any voltages if i manualy select av with my remote?

Yes, you'll be fine.

is it  ok to just twist the wires together because im not good at soldering. lol

Your cable will likely fall apart without soldering.  However, if you can get a new SCART header with blades in it, you can use small quick-connects and crimp them onto your wires.  But then, good crimping is another skill which you may not have ....

My advice:  practice your soldering technique.  ;D



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Re: How to use SCART for our hobby
« Reply #35 on: June 07, 2008, 06:09:59 pm »
Aehn, neither's that hard, though crimping is easier if you have a crimper. Using plyers...well, that kinda blows.
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Re: How to use SCART for our hobby
« Reply #36 on: June 15, 2008, 09:45:18 am »
i want to have a go at building one of these cables tomorrow but im slightly confused,

i will be using soft15hz and a standard uk scart tv, im confused about all the resiistors and supplyting voltages iv read a couple of other webpages on this and the didnt mention any resitors or adding extra power.

im unsure of what i should do. do i need to add resitors if im using soft15hz and a scart tv also my scart tv is widescreen, if i dont supply any voltages and i select av with my remote will my tv show the picture in widescreen?
« Last Edit: June 15, 2008, 09:47:35 am by Jox43w »

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Re: How to use SCART for our hobby
« Reply #37 on: June 15, 2008, 09:53:26 am »
http://homepage.ntlworld.com/callum.henderson/basement_boomera_000007.htm

iv found this diagram which differs from the one here which is making me evern more confused  ???

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Re: How to use SCART for our hobby
« Reply #38 on: June 15, 2008, 05:47:17 pm »
http://homepage.ntlworld.com/callum.henderson/basement_boomera_000007.htm

iv found this diagram which differs from the one here which is making me evern more confused  ???

RESISTANCE IS FUTILE ... heh, just joking, I couldn't help myself.

That diagram is wrong.  Follow the postings here.

If you want to avoid using resistors and voltage, follow my earlier suggestions (link SCART pin 20 -> pin 16) and use your remote to change to AV mode if necessary.  You should be fine.
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Re: How to use SCART for our hobby
« Reply #39 on: June 15, 2008, 10:48:06 pm »
Quote
That diagram is wrong.  Follow the postings here.

Hmm.  On looking at that diagram again after some sleep (rather than 5am), the diagram is not wrong, but confusing. If you follow the numbers in brackets in the figure this fellow has used ("standard configuration"), then it corresponds to a standard SCART pinout.  What he/she has used is equivalent to linking pin 20 to pin 16, as I've suggested.  He/she has also put 12v to pin 8, to signal AV mode in 4:3 aspect ratio (12v may be unnecessary if your TV stays in AV mode after cycling the power on/off - or you could use your remote for this instead).
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