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Help with an old monitor

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twolazy

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Wouldn't it just be easier to throw in an NEC multisync? It does SOG, cga, ega, mcga etc. And alot of them even have the bnc connections required on back.
 

leonphelps

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I am looking for a small NEC monitor. The monitor goes in the wall of a granite building. Originally, there was a 8" monitor there. A 14" will barely fit in the hole, anything else would need to be flat panel so I could mount on the wall. I would love to get a new flat panel and try it out, but I am already over a thousand into the project and the thought of another grand for a flat panel is not too appealing.
 

RetroHacker_

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So... what happened when you connected the CGA monitor?

If the controller board really only puts out Red, Green, Blue and Intensity lines, the sync must be on there somewhere. If you hook them up and don't get a picture to sync, try jumpering Intensity over to the sync signal, or green over to the sync signal. Sync has to be in there somewhere. From your earlier postings, it sounded like you had all these signals at the monitor, but if you don't, you need to get them somewhere.

The LM1881 chip should be able to pull the sync off the video signal, if it's in there.

-Ian
 

RetroHacker_

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Looking back at the pictures you posted earlier... What is the word printed on the PCB below this connector?
sync.jpg

It looks like it says "SYNC"

If this is true, then you have Red, Green, Blue and Sync.


-Ian
 

MikeS

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Looking back at the pictures you posted earlier... What is the word printed on the PCB below this connector?

It looks like it says "SYNC"

If this is true, then you have Red, Green, Blue and Sync.
Yeah, that's what I think, that it's an RGBS monitor and the confusing labels of RGBW in one post and RGBI in another are just red herrings, especially if the fourth coax cable goes to one or both of the monitor pins R2 and R3. Too much incomplete, confusing and contradictory information making a mountain out of a molehill IMHO.

A grand for an LCD monitor???
 
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leonphelps

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check on ebay for NEC Multisync monitors with RGB inputs. yes. I have tried craigslist, with no success. All close to me are vga connectors and no ones with BNC.

The "I" and the "W" are on the cables with wire marker. They are marked at the board and at the place where they splice to the Hirose connector wiring. That is why the confusing I and W posts.

Part of the thousand I am into the project is the first LCD VGA, a CM-1, and the CM-5 and the shipping for one of them. The site is an hour away and parking hits me for $25 a pop with the four visits I have had there so far.

I guess this weekend I will head over with the other monitor and give this one a whirl.
 

MikeS

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check on ebay for NEC Multisync monitors with RGB inputs. yes. I have tried craigslist, with no success. All close to me are vga connectors and no ones with BNC.
Yeah, I was thinking more of a normal LCD monitor with a converter, once we finally nail down just exactly what we're dealing with. There are dozens if not hundreds of them out there, as well as many different BNC to [whatever] cables, but these days many are for VGA input, not 15KHz NTSC RGBS.

The "I" and the "W" are on the cables with wire marker. They are marked at the board and at the place where they splice to the Hirose connector wiring. That is why the confusing I and W posts.
The markings on the cable don't mean much, if anything; as Ian says, what matters is what it says beside the BNC jacks on the computer end and, if anything, at the old monitor.

It would really be useful if you could list what pins the four BNC cables originally went to in the Hirose connector, if there were any jumpers inside either of those connectors, and where they ultimately went on the monitor board, i.e. R1 to R6 and/or any other places; I'm afraid I couldn't quite follow your description about a "video signal," shared shields etc. (although we did figure out what those IC numbers really are ;-) )

Part of the thousand I am into the project is the first LCD VGA, a CM-1, and the CM-5 and the shipping for one of them. The site is an hour away and parking hits me for $25 a pop with the four visits I have had there so far.
Hope someone else is paying ;-) But you may end up using the VGA LCD.

I guess this weekend I will head over with the other monitor and give this one a whirl.
Sorry, what exactly are you giving a whirl this time? Must be getting pretty frustrating..
 

Chuck(G)

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It has occurred to me that we're speculating a whole bunch.

Back when big-screen EGA monitors were hard to come by, I picked up a surplus Daisy monitor made by Mitsubishi. Heavy bugger--weighed about 90 lbs and put a permanent sag in my desktop. But it had 4 BNC connectors and ran at EGA scan freqencies. The inputs were RGB (analog) and Sync. "But how do you drive an analog monitor with TTL signals?" I hear someone ask. Easy--you make an R-2R DAC, which, if you're only looking at 4 levels per color, is quite satisfactory. I used a battery-powered (4 AA cells) 74LS86 to combine (and invert) the sync signals from the EGA. It worked marvelously.

It seems to me that we're poking at elephants with our eyes closed.

Might the OP have access to the schematic for the controller driving this thing? That would be of enormous help.
 

RetroHacker_

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It has occurred to me that we're speculating a whole bunch.

Speculating, yes. But it's an educated guess.

For example - we know that the old monitor uses digital video - you can tell by following the video signal on the board straight into some TTL logic chips.

We also know that it was in service since around 1984.

He mentions that it displays video from the floor the elevator is on, and it also displays information about where the car is. If it's doing video overlay from a CCTV setup, then it's gotta be running at the same frame rate as the CCTV cameras - which back then is going to be NTSC - i.e. CGA frequencies.

So far, he's tried to connect two monitors, both incompatible with CGA video frequencies, and has not gotten it to work. He's ruled out VGA (which, considering it didn't come into being until 1987, is not at all suprising) and the obscure Tandy 2000 video modes.

I think if he actually tries using a digital CGA monitor (or at least one that supports 15.75khz video), then he has a pretty good shot of getting it to work.

-Ian
 

Chuck(G)

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It would seem to be pretty odd that he's running TTL levels where there's a CCTV overlay.

Perhaps it's plain RGB with an additional composite feed (also carrying the sync signals?).

Note that I haven't following this thread for its entire length, so I probably have missed out on some important information.

Still, taking each of the coax lines one by one and feeding them into a plain old NTSC composite monitor might shed some light also.
 

Druid6900

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So far, he's tried to connect two monitors, both incompatible with CGA video frequencies, and has not gotten it to work. He's ruled out VGA (which, considering it didn't come into being until 1987, is not at all suprising) and the obscure Tandy 2000 video modes.

I think if he actually tries using a digital CGA monitor (or at least one that supports 15.75khz video), then he has a pretty good shot of getting it to work.

-Ian

The CM-5 is a CGA monitor with a 15.750 KHz HSync frequency, so, not too incompatible with CGA frequencies, I'd say.

You can, pretty much, rule out VGA or EGA since the CM-1, with a 26.4 KHz HSync is almost right in the middle of the HSync for VGA and EGA and would have been able to, with a lot of HHold adjustment, get close to the sync point on either output.

We need to see the inside of the Hirose connector on the original cable and then we would know what the 4th BNC signal really is and if there was any jumpering going on internally.
 

MikeS

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...We need to see the inside of the Hirose connector on the original cable and then we would know what the 4th BNC signal really is and if there was any jumpering going on internally.
Well, I've asked a couple of times but no answer so far; somewhere there was a cable that shared a shield that went somewhere, then there were brown and white sync wires somewhere, we don't know if that BNC is really labelled SYNC after all this, etc.; I'm getting a headache... ;-)

I think the problem was solved 75 posts ago; we just need to figure which adapter to use ;-)
 

Chuck(G)

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Well, this is the wonder of the Internet--desperately trying to do what needs to be done remotely. If any of us could put a scope on the thing and look at it up close, the mystery would be solved in minutes.

Sigh.
 

leonphelps

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well, some more info to add to the mix...lol.

I tried the CM-5 monitor. I got nothing. I tried with only RGB, then with the others connected (intensity and sync's) and still no result.

I did notice on the board that where it said sync it also said B/W under it.

I have the BNC to hirose cable and will get it apart tonight.

If I knew what to do with the scope, I would buy one and find what you think I need to get.
 

MikeS

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well, some more info to add to the mix...lol.
...and some confusion ;-)

I tried the CM-5 monitor. I got nothing. I tried with only RGB, then with the others connected (intensity and sync's) and still no result.
You tend to be a little vague; it's my understanding that aside from R/G/B there's only one other signal coming from the system, so where are you getting Intensity and Sync(S) from? And exactly what cable/pin/connector are you connecting where? And do we know the CM-5 works?

I did notice on the board that where it said sync it also said B/W under it.
Sounds like composite sync; have you got a TV or monitor with a composite input (the yellow RCA plug/jack) by any chance?
 

Druid6900

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Well, it looks like the CM-1 ws the only one that "worked", so, now all we have to do is built something that will crank 15.750 KHz up to 26.4 KHz. Maybe something variable with a little tiny frequency counter in it with nice big red 7-segments so we know WHAT THE HELL THE ACTUAL OUTPUT FREQUENCY IS !!!

Sorry, I don't know what came over me.....
 

leonphelps

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As for the CM-5, when I hooked it up to a cable with RGB pinned I got no flickering of the screen, nothing but white screen.

For the cable, I tested it tonight. I got the following

1
2 Red center
3 Green center
4 Blue center
5
6 ground (R,G,B,S)
7 S center
8 S center

Now to throw something else in the mix, I did the following and hope to try it tomorrow. I bought a converter like I had shown earlier in an ebay auction. It is made for converting EGA/CGA/YUV to VGA. I made a cable from 4 BNC's to the board with R/G/B/S. I also made the power connector. It has been a while since I made a custom cable like this with Coax but it actually turned out decent with the shrink wrap covering up the solder connections.

Lets hope this one does it for me.

Thanks for all of the help so far guys. It is greatly appreciated.
 
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