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RGsB (RGB Sync on Green) output to VGA/HDMI/DVI

reinhardtjh

reinhardtjh

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Jan 15, 2014
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Location
Fort Worth, TX
Does anyone know of a circuit or device that is capable of converting a RGsB output to feed some more modern LCD or flat display - VGA/DVI/HDMI? I have a DEC Gigi VK100 that I'm working on cleaning up and I need something to test it with. I do have a (large and heavy) Sony Trinitron monitor that I think can do Sync on Green but it doesn't fit well on my workbench and I have to dig it out of the pile in the garage. I'd like to pair the Gigi with some sort of smaller display - at least for testing.

I've spent a lot of time with Google and there seem to be a lot of devices for RGB with separate sync signals and not so much for the Sync-on-Green variety. I've found some old links talking about devices that have been discontinued ages ago and are only on Ebay at what seem like high prices (maybe they aren't but they're high to me). I've also found a number of devices/circuits for going VGA to RGB, but that doesn't help much.
 
We have kit that produces RGsB and use eye-watering priced monitors.

We did find a monitor that would work with RGsB "by accident". The chipset within the monitor had support for RGsB, but this was not advertised in the Specifications for the monitor. The reason for this was that the chipset they were going to move to next did not support RGsB. As a result, it was going to be "luck" that would dictate whether the monitors we purchased did (or did not) support RGsB!

Historically, I also used an RGsB to XGA converter from Extron I believe(?). These (or something like them) are probably what you are referring to and are probably well and truly obsolete by now.

Have you looked at the RGBtoHDMI converter to see whether it will do it - or could be converted to do it?

Dave
 
Extron wise, the ss200 IIRC will happily strip sync on green to RGBS or RGBHV. They used to pop up cheap here and there. Then you'd have to use any other device like rgb-dvi or rgb-hdmi, which could get pricy extron wise but are nice devices.

I probably have an extra ss200. Only hitch is one side is only 5 BNCs, but one side does have the da15 vga connector.

I didn't see one for sale but this looks promising if normal vga works for you. You'd need a pair of vga to bnc cables and that should be it unless you need digital conversion or upscaling.

www.ebay.com

Extron PA 250 PA Peaking Amplifier & Sync Stripper for RGBHV | eBay

Compatible with RGBHV, RGBS, RsGsBs, and RGsB. Type: Peaking Amplifier. - Dip switch selectable sync combining and stripping. Model: PA 250. - 250 MHz (-3dB) RGB video bandwidth. Condition: Used. Working condition.
www.ebay.com
 
reinhardtjh said:
Does anyone know of a circuit or device that is capable of converting a RGsB output to feed some more modern LCD or flat display - VGA/DVI/HDMI? I have a DEC Gigi VK100 that I'm working on cleaning up....
I've spent a lot of time with Google and there seem to be a lot of devices for RGB with separate sync signals and not so much for the Sync-on-Green variety.
Click to expand...
How fortunate for you that you have a separate sync output as well! It's the one on the back labeled "Monochrome (Black and White) Video Output Connector."

The only trick is that this will be 0.3 V rather than TTL, so your device has to accept those lower levels, but that's fairly common. It will also have a video signal on that output, but pretty much everything reading sync will ignore that.

And don't forget that you also have separate H and V sync on the board itself, if you feel up to bringing those signals out.
 
Keep in mind that the output from the VK100 is 15khz. It won't work with most standard VGA monitors. That being said, the Extron box above will do the job, or the OSSC will handle it no problem. Both natively handle sync-on-green video and will upscale to something a VGA or HDMI display requires.

cjs said:
How fortunate for you that you have a separate sync output as well! It's the one on the back labeled "Monochrome (Black and White) Video Output Connector."

The only trick is that this will be 0.3 V rather than TTL, so your device has to accept those lower levels, but that's fairly common. It will also have a video signal on that output, but pretty much everything reading sync will ignore that.

And don't forget that you also have separate H and V sync on the board itself, if you feel up to bringing those signals out.
Click to expand...
The composite video signal can be converted to TTL composite sync + vertical sync using a cheap LM1881 based circuit.
 
I have been surprised to find that most of my VGA flat panel monitors accept sync-on-green despite it not being in the spec. I also have a later EXXTRON that outputs HDMI which also accepts sync-on-green...
 
So, in case of Mono composite video output (from b/w DEC Pro) is need to be connected to Extron rgb-200 G input line only?
 
anasana said:
So, in case of Mono composite video output (from b/w DEC Pro) is need to be connected to Extron rgb-200 G input line only?
Click to expand...
No, if you want RGB you need to connect all three of the R, G and B output lines to the appropriate R, G and B input lines of the display device. The mono composite video output goes into a fourth connector, the "composite sync" input of RGB devices that don't accept sync on green.
 
Hi - I have been repairing a couple of Gigis and had this problem - I have a small Sony professional monitor that works well - and some of the larger ones are also suitable, but the frequency is not quite standard PAL...

Mine is a PVM-9045QM

You also have the mono output that can usually be used to plug into a sync input if needed...
 
I'm using an OSSC (Open Source Scan Converter) with my GIGI and it works fine - no configuration required. BNC to RCA into the OSSC and then HDMI to the monitor, you just select RGsB from the remote. I have the bitfunx version from Amazon, but would have bought the original (https://videogameperfection.com/products/open-source-scan-converter/) if they were in stock at the time.

Goes without saying, but also great for all your other RGB retro gear - especially if you can get a SCART cable.
 
Thanks everyone for your input! I did a knee-jerk reaction at the beginning and got a Extron PA 250 from Ebay. I see I need to pair it with one of the RGB to VGA/HDMI converters you find all over Amazon and Ebay. But it really looks like what I'd want is the Extron SS 200 that @skate323k137 mentioned. Or the OSSC, but that's pretty pricey compared to the other solutions. It looks very nice though. If other things don't work out then I may go that way. The goal is to have a nice display to take to VCF SW this June or next year (depending on what I have to do and how many TUITs I have available.).

In respect to the LCD VGA monitors that do SoG and 15kHz I found a web site that has a list of monitors and their compatibility.
List of modern monitors that support 15 kHz analog RGB signals

I just now looked up the Extron RGB-HDMI 300 A and that looks interesting also. The flat screen I was going to use is VGA but I have an HDMI available also. I'd just need a BNC to VGA cable since it doesn't have separate inputs.

I haven't seen an Extron RGB-200 device. All that shows up on the web site is the DVI-RGB 200 which I don't think is the same thing. If anyone has a link to a description, please let me know. Or if it IS the DVI-RGB 200 then let me know I'm confused. 🤪

Thanks again!
 

reinhardtjh,​

Glad to see you are the guinea pig for getting the GIGI working with a modern LCD. I have a GIGI as well, but have only used it with a mono monitor. It would be fun to get color up and going so I can play around with ReGIS color graphics.

Please keep us updated on your progress.

Marvin
 
atariquest said:

reinhardtjh,​

Glad to see you are the guinea pig for getting the GIGI working with a modern LCD. I have a GIGI as well, but have only used it with a mono monitor. It would be fun to get color up and going so I can play around with ReGIS color graphics.

Please keep us updated on your progress.

Marvin
Click to expand...
In addition to the aforementioned Extron PA 250, I found several cheap (ish) Extron RGB-HDMI 300A's and got one of those, too. Plus a VGA-to-BNC cable (also from Extron). I haven't gotten the RGB-VGA converter to try with the PA 250 yet so the RGB-HDMI 300 will probably be the first attempt. Now I just need to get my Gigi back in one piece to try them out. Work has been a b*tch and I haven't had a chance to replace the RIFA caps and do a general cleanup. The case is two-toned from UV discoloration (I assume) and I'm contemplating doing the Retro-Bright treatment while I have the shell in two pieces.
 
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