Viewsonic P815 monitor

[BurgerKingDiamond]

I got this 21" Viewsonic P815 monitor on Craigslist for $40. I was surprised to find that there are RGB inputs in addition to VGA. There's R,G,B,H sync, and V sync. So, I could use this for real arcade PCB's right? I would just have to put on the right connectors from the JAMMA harness right?

[MonMotha]

Specs I found say: H Freq/ V Freq - 30-115 Khz / 50-160 Hz

So you can't run most arcade boards on it as most arcade games run at 15 or 25kHz which are too low for this monitor.

FYI, "VGA" is "RGB".  It's just on a different connector than most arcades would use, the signals are smaller (you can fix it with some resistors or a video amp, depending on which way you're going), and the resolutions are very different (and that you can't fix, which is why you can't use this monitor with arcade boards).

[BurgerKingDiamond]

Ok. That all sounds about right. But what is the point of having a VGA input and RGB inputs on the monitor if they're the same thing?

[MonMotha]

A lot of high end workstation targeted monitors have the HD15 "VGA" input and a set of 5 BNC "RGB" inputs for a couple reasons:

1) The BNC connections allow extremely high resolution video signals to pass with less distortion and blurring.  2304x1440@80Hz look or 1920x1200@95Hz looks a fair bit better on my GDM-FW900 CRT sets on the BNC inputs than it does on the HD15 "VGA" input even with a high quality VGA cable.  The HD15 connector just isn't designed for super-high bandwidth signals like that.

2) It has been common on workstation setups for years to have a PC on the "VGA" input and a "workstation" (e.g. professional UNIX CAD box) on the BNC input.  This is largely historic now that most CAD workstations and similar are just PCs, but some people still appreciate it.

The HD15 "VGA" connector actually has some capabilities the BNC "RGB" interface doesn't: it will tell the PC what resolutions the monitor is capable of.  There's no way to do that on the BNC "RGB" connection, so you have to configure it all manually.

[Jack Burton]

You can't connect a real pcb to this without a converter, however you will be able to utilize native resolution display through double refresh modes in emulators.

With Soft 15khz you can program your video card to display low resolution signals at twice the refresh rate they would normally appear.  This will allow your monitor to display the signal.  For example, if a game originally ran at 320x240 at 60hz, you will now run it at 320x240 at 120hz.

There is no real downside to this.  The only difference between this and the real native signal is there will be less flicker in the image.  Most users consider this a good thing. 

The dot pitch of this monitor is very fine, so your scanlines will be more pronounced than with a typical arcade monitor of the same size.  In my experience this has been a non issue.  If it really bothers you use your monitor controls to shrink the image a bit or just sit a little farther back.  If you plan on using it in a cab it should be fine. 

[StephenH]

This might allow you to run a real PCB on this monitor:

http://www.ambery.com/rgbcgatovgac.html

[Jack Burton]

You can't connect a real pcb to this without a converter....

Just going through some of my old posts.  Sometimes I say really stupid things.   

You CAN connect a real pcb to this monitor.  It just has to be one that outputs 31khz video. 

[BurgerKingDiamond]

No problem. I was talking about 15Khz pcb's.