Why does arcade chassis use more than 0.7V for RGB?

[AE35]

Hi all!

Just as a general thought; why does arcade chassis use 2-5V for the RGB, when
everything else in RGB use 0.7V ? Like TV's and PC monitors etc.

Hope someone can clarify

Thanks!

[dextercf]

Why does girls need $1000 handbag, when men manage to put their keys and cellphone in their pockets?

[AE35]

I don't know that either, maybe someone can explain that too

[MonMotha]

Old PC monitors (CGA and EGA) used ~3-5V signals, too.  The reason is that, back in the old days, the video signals were generated by simply outputting a TTL logic signal (for 8 colors) or making a crude DAC out of TTL gates and a few resistors to get extra colors.

Back when resolutions were low, this worked fine, but as resolutions got higher and people wanted more colors, it got tough to build a high end (high speed, accurate) DAC that could drive that kind of signal level into properly terminated coax cable, so the PC world went to the same 0.7Vpp (1V with embedded sync, which is common in broadcast, but somewhat rare with computer video) standard used by television.  The TV people had always needed lots of colors at somewhat higher resolution, and they needed longer transmission distances, too, which had driven them to coax cable a long time ago.

Arcades have not typically used very high resolution, and they never need to run the signal very far, so they've until recently avoided the use of coax and proper termination.  Most VGA (480p) and higher arcade monitors do have 75ohm coax inputs, often on the familiar HD15 connector used by PC VGA and even earlier by the broadcast people, and accept 0.7Vpp signals on that connector, but the older monitors still just take "TTL level" video of ~3-5Vpp.

In other words, as usual, "it's historic".

Now, I don't have any explanation for the handbag thing.

[AE35]

Thanks!! Very nice. So, that's also why the video is unshielded on arcade games I take it.
I always thought it was strange

[Thenasty]

Now, I don't have any explanation for the handbag thing.

Only a Woman can answer this I'm afraid. 

[dextercf]

Now, I don't have any explanation for the handbag thing.

Only a Woman can answer this I'm afraid. 

Not sure if even a woman can..

[Jack Burton]

You know, it would have been so much simpler for this hobby if arcade monitors used the same connections and video standards as TVs. 

Somewhere back in history  got messed up.  Europe got sort of lucky with SCART, but even that is a pain to get working.  Can you imagine if TV's and arcade monitors just flat out both had RGBS connectors on the back? 

[dextercf]

Or if EVERYTHING had One standard connection.. Hdmi?

[Jack Burton]

Or if EVERYTHING had One standard connection.. Hdmi?

Right.  I have some serious criticisms of HDMI, but the concept of a high quality all-in-one cable is the right direction.  

Everything used to have one standard connection btw.  It was called RF, or as you may know, a coaxial cable.  It had video and audio built in.  For probably 50 years or more it was all anyone used for television.  It wasn't until the late 90s that the average person started to branch out.  Jeez, I remember when I finally got a tv with composite input and I thought it was awesome.  

[Bravo911]

Well, I can say that connecting the old nes to an ntsc tv through coax compared to the rgb connection of an arcade monitor, I have never seen a nes look so good. As for the voltage and handbag, no idea.

Sent from my XT910 using Tapatalk

[Jack Burton]

That's funny, because there's no a large movement within NES emulation to also emulate the effects of NTSC and RF modulators on the image.  There are some merits to the argument that using those connections actually -improved- the NES's image.  I certainly prefer to play the games on an oldish TV set through the NES's on-board composite video compared to any of my RGB monitors.