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Help with an RGB Conversion...

I am the owner of a recording studio in Minneapolis and we just purchased a new (to us) recording console. The console is 20 years old and runs off of a computer the same age. We've been trying to find a solution for a video feed from RGB outputs. I have talked to every electronics outfit in town, scoured the internet (including Google Groups) and haven't been able to find a definitive solution for this. Seems there are a number of different scenarios, and I would greatly appreciate some help on this.

Here is the best I can describe what we have...

There are (of course) the 3 R, G and B outputs on the computer. In addition, there is 1 Sync output, only 1. We have a 5 (one too many) BNC to VGA cable, but I believe this is typically used to send signal from VGA to RGB (right?). Along with the R, G & B on this cable, there is a Vertial and Horizontal. We've tried connecting this cable to a newer VGA monitor in a number of ways. There are 2 cases where we see anything at all. First, when we connect any one of the colors to the Sync we do see staticy Horizontal lines of that color. Also, when we connect the Vertial Cable to the single sync output, the monitor indicates a "frequency out of range" error. We are, on the other hand, able to get a clear and steady signal on and older monochrome monitor using a Single BNC to Single BNC cable, if we connect this cable to the Green BNC output on the computer. We also get signal on the red and blue, however the image isn't stable.

In any case, I'm looking for the most cost effective solution. I have found a couple of older RGB monitors on Ebay, but all seem to have only the 3 (R, G & B) inputs without the Sync input to match the Sync output on our computer. If this will still work, great. We'll buy one. I'm concerned about that fourth (Sync) output however.

Can someone tell me definitively if buying one of these monitors will work? And if not, what a good cost effective solution would be?

Many thanks!

Eric A440 Studios

Reply to
trelster
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You must have a Sync-on-green output, then. I don't know why would they have a separate sync, then, but those sync-on-green monitors will probably work for you, unless the frequencies your computer outputs exceed the monitor specs. Can you measure the frequencies on the green and sync outputs?

Also, there are adapters from SoG to VGA, which has separate R,G,B,Hsync and Vsync signals. This one might do:

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Reply to
przemek klosowski

How about this? Its not my design but I did use it before. A 2N3904 works in place of the BC548.

100 uF ! ! Green ----! !--------------------------------- -! !+ ! ! 680E ! BC548 ! HSync ------------- __---------/\\/\\------o--------- CSync on Green \\ /! \\ / --------- ! ! 1k ! VSync ----/\\/\\---------- [note by the poster: for those guys who know exactly as much about electronics as me, BC548 is a transistor, the /\\/\\ 's are resistors and the 100uF is a condensator. :) ]

This one works perfectly without _ANY_ logical circuits and thus needs _NO_ 5 Volts or anything else ... ;)

Note: This works only with syncs that are active low, but since this is the default for _any_ sync signal, you would not have to expect any problems with this circuit.

Note2: when you build this with SMD you can put the whole circuit in the VGA connector of the cable. ;)

so long, MadMax. >>>--- for questions contact this guy!

Reply to
Adam Stouffer

Reply to
chris.hogg

I have a working older Veiwsonic model 20G color monitor that uses 5 input cables that sounds like what you are looking for that I might be willing to part with for the right price. I measured diagonally across the part of the screen that is visible and it measured about 18 inches. Let me know if you are interested Send email to snipped-for-privacy@duncanelectronics.net.

Reply to
DuncanElectronics

Two things, 1) It could be a composite sync output, 2) since it's video the system probably outputs stuff at 50 Hz which is too low for a modern VGA monitor.

You could try finding more information on the computer in the console (it could conceivably be an Amiga 1000 for example). Also you could try measuring the vertical & horizontal sync frequencies (eg using a 'scope) so you have an idea what specs the monitor you're buying will have to handle.

--
Daniel O\'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
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Reply to
Daniel O'Connor

trelster scrobe on the papyrus:

At that age and with four wires it is most likely to be a TV standard RGB and composite sync signal. Either 525/60 or 625/50 depending on the country of origin. If you have access to a scope take a look at the sync signal and see what the frame rate is and how many equalising pulses there are in each field sync. 525/60 has six equalising, six field serration and six equalising. 625/50 has five of each. Either way a cheap CCTV monitor should work correctly, although you may have to adjust the vertical frequency to get it to lock.

--
John B
Reply to
John B

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