(From Michael Scott and Bill Nott)
There are plenty of old RGB monitors (possibly from old Sun, SGI, or other workstations) around which are attached to outdated or non- functional machines. Most of these units are quality products by Sony, Hitachi or other vendors. You want an easy way to connect your VGA or better card to the monitor. It's may not be that easy, since many of these monitors are only capable of displayed non-standard pixel addressabilities, but read on..
The easiest solution (but not necessarily the cheapest) is a commercial solution. See the section from Declan Hughes, below.
Most of the old RGB monitors are fixed frequency, meaning that they are intended to work at only specific horizontal and vertical scan rates. This is in contrast to many newer models which are variations on the multi-sync theme. Multi-sync means that the monitor can sync to a RANGE of scan rates, or a number of discrete scan rates, based on the incoming video signal. i.e. the monitor will detect the scan rates of the video signal, and switch to the closest scan rate it is capable of. Since a fixed frequency monitor can't do this, you have to make sure that the video signal your video card is generating is compatible with the monitor.
To hook up a VGA card to a fixed frequency monitor requires three things:
A frequently asked question is how to use a fixed frequency monitor (often a Sony or Sun monitor) with a PC AT. Three companies that provide the required video cards are:
(From Michael Scott)
They have three models which use popular video chipsets:
Model Chipset Max RAM Bus ===== ======= ======= === Wind 1280s ET4000W32P 2 MB ISA, VLB, PCI Storm 1600s-Pro S3 64-bit 4 MB PCI Wind 1280s-Pro ISLNG Viper 128 4 MB VLB, PCIDrivers are available for Windows 3.1, Windows 95, OS/2 Warp, ACAD, Linux, lots of CAD programs & VESA compatible applications. All cards support separate sync and composite sync as well as sync on green. Software comes with the cards to adjust frequency, setup and centering.
Mirage will give you a special discount if you mention that you were referred from this FAQ (No, I don't get anything in return :-( )
(From Declan Hughes)
For example, a STORM 1280/256 will drive a Sony GDM-1950 at 640x480, 800x600, 1024x768, 1280x1024 and DOS modes (this monitor is rated at 63.34Khz Horizontal sync. and the card runs at 64Khz Horizontal sync.). This card uses an S3 graphics accelerator. See also PC Magazine/April/13/1993.
Software Integrators make similar video cards (the MERCURY X1 Series) that will also support CGA modes as well as DOS, EGA and VGA modes using the S3 801 graphics accelerator and again they also make fast drivers for specific products such as Autocad, 3D Studio and Windows 3.1 etc.
These cards work with all fixed scan monitors including, IBM, Mitsubishi, Hitachi, Sony, Sun, HP, Verticom, DEC, Taxan, Philips, Apollo, Silicon Graphics, Intergraph, Aydin, Amtron, Monotronix, etc. and will replace old boards from, Artist, Number9, Nth, Verticom, Photon, BNW, VMI, Matrox, Metheus, Mirage, Graphax, Imagraph, TAT etc.
PCG provides several models, supporting ISA, VLB or PCI buses and their cards can support 1, 2 or 4 MB of video RAM. CL-5434 processors appear to power all of the Photon cards. They support sync-on-green (RGB) monitors, Windows95, Win 3.1, Linux and provide a variety of video drivers for various applications. Cards automatically boot up with a frequency compatible with your monitor.
For more information, refer to the Fixed Frequency PC Video FAQ at: http://www.wit.com/~xtian/video.html
All companies can supply interface cables such as a 15 pin male VGA to 5 BNC connector.
I have gleaned this information from sales sheets faxed to me, I am purchasing one of these cards, I am not related to either company, and both sales staff were very helpful (so please ask them for more detailed information).
I was also informed of a German manufacturer ELSA that makes similar cards, but I do not know of their address or product range.
(From Bill Nott)
Nobody has dealt with the radiated emissions issue. All PC's are marketed as FCC class B products. I recently learned that Mirage labels their cards as Class B. However, most of the single frequency workstation monitors becoming available are FCC Class A, and the FCC rules say that attaching a Class A device to a Class B system degrades it to a Class A system. This in itself is not necessarily a problem, unless the system is actually found by the FCC to be causing radio interference. My recollection is that the process of remedy for a Class A system is more severe than for a Class B system, so users may be opening themselves up to a higher level of risk. Comments are welcomed on this.
For more information on how others have done this, read pertinent parts of this FAQ and refer to:
USE AT YOUR OWN RISK - Others have used this circuit but I have not!
From VGA card To RGB Monitor
Red 1 O---------------------------------------------------------O Red
Blue 3 O---------------------------------------------------------O Blue
Green 2 O----------------------------------------------o----------O Green
|
4066 | Sync level adj.
___________ ________ 4 |
2 \ \ | ___|_______| __/\/\/\--O +5V
H sync 13 O--------\ 74LS02 \ 1 5 | | | SYNC _|_ ^
| (DIP) |O------------>\ | //// |
V sync 14 O--------/ / SYNC | |__|________________|
3 /__________/ | | 3
| |
| ___|___ *
| | |
* --->\ |
| |__|___ *
|______|
* tie to ground
Red 6 O-----------o---------------------------------------------O RGB
| Cable Shields
Blue 8 O-----------o
|
Green 7 O-----------o
|
Returns _|_
////
If no sync is present from the VGA card, pin 4 of the 4066 is in a
high impedance state and does not affect the green video signal.
If either horizontal or vertical sync is present from the VGA card,
the positive sync voltage is gated onto the green video line. This
"wire-or" of the signals seems to work!I think that the video voltages presented by the VGA are a bit on the low side for the RGB monitor. It would be nice to have a video op-amp circuit to provide 1-3 dB adjustable gain on the RGB signal possibly using the NE592 video op-amps. The pinout for the 74LS02 is the more common one. Some flatpacks use pins 1 & 2 as imputs instead of 2 & 3. Use this circuit at your own risk. Good luck!
Go to [Table 'O Contents]