#Multiple RGB Monitors
25 messages in this thread
Does anyone know if I can daisy chain several (at least two) RGB monitors
together? I need to set up a display at a festival. I will be usin the
Amiga 2000 with a total of 3 monitors. Two monitors for the gawkers and
one for me to run the software with. If I have to I will work off the
composite B/W output.
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I think you can get a signal splitter from any good electronics or camera
shop…not sure what the price would be, or what the effect on your video
output would be (I suspect not good, but the person in the shop would
know.)
Paul, I'm in the medical electronics service field. We set up trade shows
every year, so I'm very familiar with what you want to do. Running RGB and
sync cables to multiple monitors follows the smae rules as running a
composite cable. The last monitor that you connect to should be the only
monitor with 75 ohm terminators on it for each cable. A good RGB monitor
will have RGB and sync inputs and outputs as well as terminator switches.
The switch is usually labeled 75 ohm and high Z. I'm assuming that you are
going to use coax cable with either BNC or Phono plugs on them. You could
use T-connectors to go to each monitor, but the middle monitors still have
to be unterminated or each termination will divide down the amplitude of
the video signal which will degrade the quality severely. Bruce Patek
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Bruce, let's see if I get this right. I will need a box to convert the RGB
signal from the Amiga to BNC or RCA plugs. Would this be a simple cable
converter or do I have to go through a Genlock with BNC out?
Could I connect a splitter to the end of my monitor cable and run two Amiga
monitors? Or would I end up overdriving the video signal?
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Paul,
To drive Sony (or other professional) RGB monitors you don't need an
adapter BOX — you just need an adapter CABLE. It's got the familiar
23-pin connector on the Amiga end, and four BNC connectors (Red, Green,
Blue, and Sync) on the other end. Redmond Cable has them (I don't have the
address but they advertise in all the major Amiga mags) or you can buy them
at many local dealers. As for the Commodore monitors, they all have
built-in, nonswitchable termination. If you knew how (or had access to
someone who did) you could open up one of the monitors and remove the
terminators (only the last monitor in the chain should be terminated). But
it's probably more trouble than it's worth, and renting some pro monitors
for a day will give you better image quality anyway. Make sure the
monitors you get have RGB loop-through capability — some don't (like the
Commodore monitor, the terminators are built-in and nonswitchable, and
there are no loop-through connectors).
Hope this helps.
Pete
Pete
Thanks for the info. Hooking up the pro monitors sounds fairly simple. As
for the Commodore monitors having nonswitchable termination… Where is my
soldering Iron??!!
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Paul,
Actually, the built-in terminators will be nothing more than 75 ohm
resistors from each of the four signal lines (R, G, B, and Sync) to ground.
They will likely be right near the connector.
Pete
Pete,
Great! My soldering iron is now warmed up!
Paul
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Paul, as far as getting the individual R,G,B and sync out of an Amiga, you
would have to make an adapter pigtail that has the "har to find" 23 pin
connector on one end. Inside the adapter, you would solder one coax to pin
3 (R), pin 4 (G), and pin 5 (B). As far as sync goes, you should only need
the composite sync at pin 10.
I made a similar adapter for myself, except with a 9-pin connector
instead of separate coax connectors, so that I could connect my multisync
monitor to the Amiga. Not to confuse you, in my case the multisync needed
separate H and V sync signals which are also output by the Amiga. I use an
article in Amazing Computing V3.1, 1988. It explained how to adapt a
multisync to the Amiga.
Unfortunately, your not going to br able to buy an adapter like the
one you need because of the Amiga's weird 23 pin connector, although maybe
you could have it made for you. If you have doubts about building such a
cable or possibly voiding your Amiga warranty, then maybe you shouldn't do
it.
As far as needing the genlock, there would be no reason or advantage
to using it. The video signals would still be the same. The only key to
using multiple display monitors is having only one terminatiom and at the
end of the chain. By the way, this setup would not allow a normal Amiga
monitor to be connectd at the same time, since there would be no place to
connect it.
Your mission would be a lot simpler if you daisy chained composite
monitors using the output of a good genlock, like a Supergen, but then you
don't have the RGB image quality. I'm sorry this message is so long, but I
couldn't think of a short way to say it. Bruce Patek
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Thanks Bruce. I am going to rent the equipment from a video graphics shop.
They should have everything I need. As for the hard to find 23 pin
connector, I know of a couple of electical supply houses that stock tons of
used parts. Do they have connectors? Tons of connectors. Shelves full of
connectors. Why they should change thier name to Connectors R Us.
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Paul,
Don't expect to find the D-23 connector at the place you're talking about.
None of the usual manufacturers of D-sub connectors make a 23 pin model.
There are 9-pin, 15-pin, 25 and 37. No one who does normal marketing of
these connectors sells a 23 pin model. The ones that do only sell
wholesale and will want you to buy thousands of them at a minimum, because
no manufacturer I've ever heard of in this country uses them except CBM.
Give it a try anyway if you want — but keep Redmond Cable in mind if it
doesn't work out. They've got 'em.
Pete
Paul,
Call DKB Software at (313) 960-8750 and ask about the DB23 connectors.
We have them available and will sell them for a reasonable cost. (I don't
know the cost off hand, as I'm not at the office now) A good time to call
would be M-F 10:00 AM to 6:00 PM EST.
Dean
DKB Software
Dean,
Thanks for the info. on the DB23 connectors. I don't think I will need
them this time, but I am going to save your number for future reference.
—Paul –:>
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Paul, be sure to make the adapter and try it on an RGB monitor before you
commit yourself to renting any equipment. I am not 100% sure that the
composite sync signal alone will correctly display a stable image on the
display, since I followed a procedure for connecting a VGA monitor to the
Amiga. The procedure had me connecting the composite sync to the horizontal
sync after soldering in a 470 ohm resistor in series with the horizontal
sync. If you're going to be inside your 1080 anyway, maybe you can ohm out
the cable and see what Commodore has connected to what. Hope this helps.
BP.
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Bruce,
The connection sceme you're talking about is rather different than what
Paul is planning. Connecting a VGA monitor is one thing; a professional
video monitor is another.
In my studio I've got exactly the kind of adapter cable we're talking
about, connecting the Amiga to a 19" Ikegami broadcast monitor, which has
four BNC inputs (for R, G, B, and Sync). It works fine (and the picture is
something you've gotta see!).
Pete
Pete, I would definitely like to know how you adapted the Amiga output to
your RGB monitor for future reference. I know the RGB signals are standard
one volt signals, but I'm not sure how to get the correct sync output. As
far as the monitors being totally different, I might have to disagree. The
multisync monitor I have is compatible with an IBM VGA monitor. The signal
input and level specs call for 1 volt RGB signals and the sync can be
separate H and V syncs, composite sync, or sync on green. The professional
RGB monitors I've seen will sync on composite sync as the forth connection
to the monitor or sync on the green input, if it has the sync signal with
it, which is fairly common. I haven't had a reason to scope the Amiga video
outputs to see if there is a sync on green, since my monitor is already
working and I haven't had a reason to connect a professional quality
monitor to the Amiga. I would appreciate the information as much as Paul
would. Thanks, Bruce Patek.
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Bruce,
The Amiga will give you R, G, B, and composite sync, so it's real simple
(no, it does not provide sync on green). Redmond Cable makes an adapter
cable with a DB-23 on one end and four BNC connectors on the other, all
ready to go.
I don't have the pinouts for the DB-23 handy, but I believe they're in
the manual (if you really need them I could probably dig them up) —
it's pretty straightforward (only reason I didn't do it myself was
because I couldn't get my hands on a DB-23).
And yes — you can go out to a multisync monitor without a problem.
But to the best of my knowledge you can not connect to a standard
garden-variety VGA monitor.
Pete, Thanks for the reply. I'll keep Redmond in mind. BP
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Another source of DB-23 connectors ($1.63 Male, $1.74 Female, chrome plated
connector hoods are $2.50) is Dalco Electronics, call them at
1-800-445-5342 for a free catalog.
I've good service from them for other stuff like A/B/C/… switch boxes,
vga monitor extension cables, keyboard extension cables, etc. They also
have a nice case complete with internal cables that is GREAT for external
SCSI devices.
Thanks, Jay. Dalco Electronics? I haven't heard of them. Where are they
located?
–Paul–:>
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Dalco Electronics has been advertising in Computer Shopper for a
while. They are in Ohio. -J
Paul Laskin 72436,3240
You can also reach Dalco Electronics here on CompuServe with GO DA.
I bought some memory DRAMS from them for a board to enhance my
bridgeboard.
Paul,
Benetech Electronics in Haltom City, Texas, has them. Area code 817, not
sure of the number, call (817)555-1212 for information.
Darin, SPC Superbase Technical Support
Paul , I forgot to comment about the splitter. You're right, the splitter
lets you connect two monitors in parallel. With both of them terminated,
this would definitely cut your video signal amplitudes in half. What you
really need is an RGB and Sync buffer with multiple outputs. This would be
overkill, sinc daisy chaining would give you the same results. BP
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Bruce, What I really need is a Wall of Video.
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