Replacing an arcade monitor with a europeen TV

[CathalDublin]

Just thinking I should be able to pick up an old 26"T.V for nothing
Can I use the scart RGB on a europeen Television in my cabinet as my monior bit the bullet?
Will I still need to use the ArcadeVGA card?
Will it work With Jamma Boards?

[Level42]

Yes
Yes
Yes

This is how I put a television as an arcade monitor into my Galaxian:
http://forum.arcadecontrols.com/index.php?topic=62784.msg624379#msg624379

It's quite simple to do.Here's a schematic:


With thanks to Darthnuno for the schematic and giving me the idea to use a TV

[grantspain]

yes that works,i used that scart pinout to test a load of jamma boards this week on my television

[CathalDublin]

Sweet, whats the quality like, will have a look at your project now
I dont need the audio d and g, right?
unless I want Audio that is

just the
Red to Rouge
Green to Vert
Blue to Bleu
Black to Syncro
and the +5 and +12 from the jamma cabinet PSU

[grantspain]

black to all the gnd(ground) connections
white or yellow to syncro(sync)

[Level42]

black to all the gnd(ground) connections

Not really neccesary. I used just one GND and it works fine. Those GNDs per color are there because on a (good quality) SCART cable, each color signal has it's own shielding (=gnd). However, all arcade games wiring I have seen don't bother about that and simply use one single GND wire, and there's no shielding at all.
The GNDs on the SCART side are all connected to.............Ground

If you don't want to use the sound from the TV, just forget about those connections. I didn't use the sound of the TV either....normaly an arcade monitor doesn't have any sound inputs, so when using this in an existing game, you probably will never use it. However, when building your own cab, there's nothing to stop you from using the TV's audio amp, which are almost always stereo and a good enough quality for arcade games.  Speakers depends on the TV of course.

If you will de-case the TV like I did, remember to bring the infrared receiver to the front. I desoldered it (it's usualy only a couple of pins) and put a wire ribbon between the original PCB soldering spots and the receiver. This way you can still adjust brightness, contrast, volume etc. with the remote. A nice bonus compared to an arcade monitor.

The only (minor) set-back is that controlling the picture position, size etc depends on how those controls are placed on the PCB, or maybe controlled via set-up menu's.

About the quality: It's exactly as good as an arcade monitor. By using the RGB lines on the SCART connector you bypass everything that could degrade the signal, and (almost) directly steer the guns in the CRT. Tuner etc. are completely by-passed.  A TV is just an "arcade" monitor with a tuner


Here's a link to DarthNuno's site /Pac Man project that gave me the idea to use a TV in my Galaxian:
http://www.dragonslairfans.com/phpBB2/viewtopic.php?t=195&postdays=0&postorder=asc&start=15
You can easily the great picture quality, as he used a brand new TV set. I used a 2nd hand one that is about 10 years old. Advantage of that is the really nice old-fashioned round CRT...

Let me know if you need more help !

[CathalDublin]

Thanks Level42 for all the info
Gonna head out now and pick up a 24"Sharp tv €65 I found second hand
as I cant find anywhere in Dublin that sells 4:3 tvs bigger than 21" new
Everything is LCD/Plasma in all the shops.

Anyway i'll be decasing it when I've tested it and decasing the old moniotor and trying to swap em if it fits,
If not i'll have to make me own bezel

I wont need the speakers or amp so i'll probably remove them to save on space/etc
Will have to move the remote control infrared reciever, whats the bets i'll forget about that

Gonna go over to maplin and pick up some crocidile clips and wire, and a scart plug.
I've been told over here discharging a monitor is not as dangerous as its made out.
true/false?
Is it just ground the screwdriver to the chassis ouf the monitor <or where> and slot it under the sucker?
keeping one hand in me pocket and the other only on the handle of the swrew driver?
How long does it take?

Lincade didnt work with me old monitor anyway and I didnt really wanna use windows

[CathalDublin]

Picked up the 24" monitor and its the perfect size
Bit of screen burn as it was out of the bookies.
Will do for now to get my project finished,
will still look for a better one, might take a few weeks to pick up a clean one

[CathalDublin]

It works,thanks a million lads
Screen burn doesnt looktoo bad except at white or grey menus

[Wade]

Okay, someone needs to locate a bunch of these for cheap in the USA.  Surely there's a recycling store or oddball tech store somewhere that carries these.

Wade

[Level42]

Okay, someone needs to locate a bunch of these for cheap in the USA.  Surely there's a recycling store or oddball tech store somewhere that carries these.

Wade

Very unlikely. Why would a bunch of (old) CRT TV's, using the PAL standard be shipped over to the US ?

I'm afraid this is one of the very few advantages of being in Europe. The SCART lets every single TV here act as a true arcade monitor. And they are VERY cheap 2nd hand now because everyone is switching to flatscreens. You won't find really large CRT's with 4:3 aspect ratio new anymore though. I guess it will get harder and harder to get ANY CRT TV new as time marches on....
Let's pray and hope that the CRT will survive in some way, just like the good old vinyl record player did....but I guess the situation is a lot different.

Cynos: Glad it works ! 
I never de-charged the CRT when de-casing it, but I know exactly what to not touch

[CathalDublin]

Think I'll discharge it, dont want to die just yet LOL

[Level42]

Well, it's always safe to do it. However the only (and first) time I did it was when I had to replace the HVT on my Star Wars.

The funny thing is that no-one ever died from it. But it does hurt. However, a fully charged electrolytic cap has more bite, and especialy anything connected to the mains.

Still, when in doubt, discharge !

[Level42]

Hey Wade, I was thinking, maybe we can ship a 20' container full of European TV's and you ship back a 20' full of classic arcade cabs

[CathalDublin]

Okay, someone needs to locate a bunch of these for cheap in the USA.  Surely there's a recycling store or oddball tech store somewhere that carries these.

Wade

Get a plane to ireland
if you want 21" you'll get them no problem for free
25"/26" is a little difficult to find though
http://dublinwaste.ie/free_trade_list.php?category_id=2

[CathalDublin]

Ah new monitor mounts are about 1inch off the old ones
Somecustomwork is in order here
Will have to do a job with a bit of MDF

Discharged both the TV and monitor, No power in em though
Not a dicky bird out of em,TV was off for 2 days and monitor about a week

[Level42]

Most relatively modern TV's and monitor discharge quite quickly (as you just discovered). Tube size isn't exactly the same of the mounts are off....but I bet you'll solve it

[Zebidee]

To improve the performance of your JAMMA-SCART cabling, try putting a 75 ohm resistor on each of the RGB signal lines.

There is a small problem with running JAMMA -> SCART TV as an arcade monitor.  That is, arcade PCBs output the video signals (RGB anyway) at a higher voltage than is normally anticipated by the TV.  If you are using a JPAC (like I was), it also has an onboard signal amplifier that boosts the RGB signal voltages to match arcade monitor levels. 

What this means is that your SCART TV will likely work ok, but will appear very very bright.  You can probably just turn the birhgtness down.  But does the higher voltage damage the TV?  Maybe.

I did JAMMA->SCART for two Sony broadcast monitors that I mounted into arcade cabs.  I wasn't really happy with the video signal, it was too bright, picture was difficult to adjust, and it just plain worried me.  It was too "washed out".  I measured the RGB voltages the levels were about 2-3 what I'd normally expect from, say, a PC or DVD. 

After I put in a 75ohm resistor on each of the R-G-B lines, the picture improved dramatically.  In fact, it was better than ever before!  each resistor costs 6 cents, so that is an 18 cent fix!   

[Level42]

Zebidee, you are absolutely right.

Exactly what I thought and actually DID with my Galaxian ! Resulst: Poor, dim picture.

I removed the resistors and bingo, great quality, no signs of "over"feeding the SCART inputs.

You are right, SCART expects 1 Vtt. Arcade games are supposed to put out 5V. Anyway, the thing I know is that it works really well without the resistors. I think I only kept the one in my Sync line.

About the JPAC: I have got one as well on my MAME cab, and I'm pretty sure it is actually over-feeding the monitor. Note that this is using a "real" arcade monitor from Intervideo. You can see that when there's a lot of white on the screen (running windows f.i.) it's simply over bright etc.

I mailed Andy from Ultimarc about it if it were possible to bypass the video amp, but he told me it was not easy to do.

Anyway, what I'm trying to say: Theory and practise are not always matching. Your example shows it does, but mine (and others) show that you have to experiment a bit.

[Zebidee]

Zebidee, you are absolutely right.

You are right, SCART expects 1 Vtt. Arcade games are supposed to put out 5V. Anyway, the thing I know is that it works really well without the resistors. I think I only kept the one in my Sync line.

Sorry to do some mythbusting, but ... I'm am pretty sure that ideally you should have resistors on the RGB lines.  I did some experimenting and fact-finding when I did this a couple of months ago

When I did my ArcadeVGA->JPAC/JAMMA->SCART cabling I checked the signal voltage levels along the cables with a multimeter to see exactly what was happenning to the signal along the way.  I did this before insulating, as it is awkward to do afterwards.  This is what I found:

From ArcadeVGA videocard, RGB signals were not more than 1v.   HOWEVER, the sync signals come out at up to 4-5v.  This means that the actual raw Sync signal is already quite high enough for an arcade monitor.

From the JPAC it gets more interesting.  RGB signals are about 2-3 times higher, or up to 2+ volts (but not 5v as some think).  HOWEVER, the sync signal comes out at about 3-3.5v ... actually a little LOWER than just raw from the AVGA card.  This surprised me, as I didn't expect the sync voltage to be lower as it came out of the JPAC.  My Sony SCART Monitor accepted the JPAC signals, but it was too bright.

After putting resistors on all of the signal lines, post-JPAC RGB signal voltage levels normalised to < 1v BUT sync levels dropped too far (1.5v or something I think), and the picture was now dim / wrong.

Then I took the resistor off the sync signal (leaving resistors on RGB), and everything was perfect!  Happy days!  Colours clear and bright, not washed out or dim.  Everyone seems to say "put a resistor on the sync line", but it just isn't true! 

In summary, although you might get away with it with some TVs, you probably don't need a resistor on the sync signal.  But you SHOULD have them on the RGB signals.

[Wade]

Okay, someone needs to locate a bunch of these for cheap in the USA.  Surely there's a recycling store or oddball tech store somewhere that carries these.

Wade

Very unlikely. Why would a bunch of (old) CRT TV's, using the PAL standard be shipped over to the US ?

I'm afraid this is one of the very few advantages of being in Europe. The SCART lets every single TV here act as a true arcade monitor. And they are VERY cheap 2nd hand now because everyone is switching to flatscreens. You won't find really large CRT's with 4:3 aspect ratio new anymore though. I guess it will get harder and harder to get ANY CRT TV new as time marches on....
Let's pray and hope that the CRT will survive in some way, just like the good old vinyl record player did....but I guess the situation is a lot different.

Cynos: Glad it works ! 
I never de-charged the CRT when de-casing it, but I know exactly what to not touch

Okay, well surely there are TV's here in the US that are basically the same as the Europe models but just need a jumper snipped or a few wires soldered in.

Wade

[Zebidee]

Okay, well surely there are TV's here in the US that are basically the same as the Europe models but just need a jumper snipped or a few wires soldered in.

There is!  But you would need to have the circuit diagram for each model TV!

[Level42]

Yep, and if you find the IC that's doing the video processing, you're close to adding an RGB input to your TV. It has been done before lots of times.

Wade, my sync is just fine with the resistor

However, you did inspire me to once again try some resistor in the color lines. Gonna try it right now actually...you used 75 ohms right...will let you know the results later !

[Zebidee]

Level42, when you add the 75ohm resistors to the RGB signals, try taking the resistor OFF your sync signal    Otherwise it'll probably be too dim.

[AndyWarne]

SCART RGB TVs make perfect arcade monitors as they basically work the same way. There is another write-up here: http://homepage.ntlworld.com/callum.henderson/basement_boomera_000009.htm
The only issue is that you need to adjust the height and width of the picture down to eliminate overscan. This is not always possible on all TVs as some need a factory service remote. But most you can get into the service menu using the ordinary remote.
If you are using an ArcadeVGA card its better to make up a direct cable from the card to the SCART connector rather than from the J-PAC (ie JAMMA connector).
Andy

[Zebidee]

Andy, I was hoping that you'd say something sooner or later.

I think we all know that technically we can just do a VGA-SCART cable and be done with it.  But the challenge here is to make a cab that you can potentially add a JAMMA PCB to.  So that the SCART TV really is an arcade monitor in every sense.  If that makes any sense.   

Having said that, I know it makes little sense to dumb down a boosted signal.  But we enthusiasts do it anyway just to prove that we can ..... 

[Wade]

Okay, well surely there are TV's here in the US that are basically the same as the Europe models but just need a jumper snipped or a few wires soldered in.

There is!  But you would need to have the circuit diagram for each model TV!

Or, find one common model.  I mean, if I figured out how to do it with a certain $60 Wal-mart TV special, then I just might buy several of them at once.

Okay... it's probably not worth all the trouble.  I just keep wishing for a good source of inexpensive arcade monitors.

Wade

[shardian]

Okay, well surely there are TV's here in the US that are basically the same as the Europe models but just need a jumper snipped or a few wires soldered in.

There is!  But you would need to have the circuit diagram for each model TV!

Or, find one common model.  I mean, if I figured out how to do it with a certain $60 Wal-mart TV special, then I just might buy several of them at once.

Okay... it's probably not worth all the trouble.  I just keep wishing for a good source of inexpensive arcade monitors.

Wade

Your best bet would probably be to find a compatible tv tube, then buy up some cheap arcade chassis. The workload and price would be about the same. You're always telling me tv tubes work anyways.

[Level42]

Level42, when you add the 75ohm resistors to the RGB signals, try taking the resistor OFF your sync signal    Otherwise it'll probably be too dim.

??

What does the sync signal have to do with the brightness of the monitor. Nothing IMHO. If the level of the sync signal would be too low because of my resistors I would get syncing problems, not a dimmer picture...

I did include the 75 Ohms resistors, and I agree that it's better now. The thing is that the really old games mainly had black screens. This results in a relatively low AC level on the video lines no matter what happens on screen.However, after I added the 76 Ohms, I was able to better control the colors with the brightness adjustment of the TV and the colors were more separated from each-other. So yes, I do suggest to always include the resistors in the video signal lines.

[CathalDublin]

Will try out the resisters at the weekend

The only problem I found with using a TV so far is
The 1st tv I tried worked perfectly Sanyo
Had manual adjustments for screen size/lin/etc

the second one a Mitsubishi
Had a service menu to adjust them
and there doesn't seem to be an option to make the screen width smaller

[ptistheboss]

If my TV has RGB inputs will this work? why not?

What it is about EU TVs that allow this ease of use?

[Level42]

If it has separate RGB inputs then yes it will work. But most TV's in the US don't have it.

European TV's are all equipped with a SCART connector. This connector can transport a whole range of video and audio signals from and to the TV. Amongst them is the RGB signals.
The SCART is a French development and from a certain year it was the law in France that every TV had SCART.

Sometimes, government rules are actually good, like in this case. Manufacturers from all over the world saw the advantages of the SCART and it was pretty easy to put it on TV's anyway.

Read this for all the info about it: http://en.wikipedia.org/wiki/SCART

[Zebidee]

Level42, when you add the 75ohm resistors to the RGB signals, try taking the resistor OFF your sync signal    Otherwise it'll probably be too dim.

??

What does the sync signal have to do with the brightness of the monitor. Nothing IMHO. If the level of the sync signal would be too low because of my resistors I would get syncing problems, not a dimmer picture...

Hey, it was a couple of months ago and I didn't "write up my observations".  But on comparison, the sync line was better without a resistor on it.  I gave it a go, but the picture was better without it  "in general" 

This outcome fits with theory, because normally a SCART TV specs say that they are able to take a sync signal 0.5v - 5v.  So, if the sync level is strong but within this range then it should be good.  and about 3.5v (from the JPAC) seems perfect (and was).  With a resistor on, the sync signal was poor.  So a resistor on sync seems unnecessary at best.

[CathalDublin]

I really need to go back to school but is
is 75 ohm violet green brown?
or violet green black?

[grantspain]

75r is violet/green/black
             7        5         0

[CathalDublin]

Thanks

[Level42]

Whaaa, I NEVER use color codes, because I can't remember them and I'm too lazy...always measure them 

AND I need a pair of reading glasses.....