Neo in RGB on a Sony PVM, but rolls on my 1084?

[Anthony1fromDP]

In the other post that I did, I explained how I recently got a Neo-Geo that had this video rolling problem on my Commodore 1084S-D1.  Anyways, I couldn't get it to work in RGB on that 1084, and the picture would just roll and roll and also bounce a little bit. Well, I finally got around to trying it on a broken Sony PVM-2530 that I have that only works for 2 minutes and then shuts off. I have an adapter for all my 1084 cables, that let's me use them on the Sony PVM. It has a female 9 pin Dsub on one side and the 25 pin (CMPTR) plug on the other side for the PVM. I had this 27 inch PVM sitting in a dark corner in my Garage, and I knew that I was going to have to pull the thing out, kill some black widows and crap, dust the thing off and just try the thing out. I knew it would only work for a minute or two before the picture just zaps out, but I figured, "Hey, for that 1 minute and 45 second period of time, I should see if that Neo works on the PVM.



So I kill a few black widows (seriously), and get everything all hooked up and set up properly, and then flip the switch and see if it works. AMAZING. I'm finally seeing the Neo in RGB and it's abstolute brilliant!!! Wowsers. First game I tried was Baseball Stars 2. Man, the clarity and crispness, and the color and detail. I love having a early serial # Geo.

Anyways, you might be wondering... "So what's the problem then?" Well, the problem is that my PVM is broken and it only works for 2 minutes and then shuts off, it's like the biggest tease in the world. I actually turned the thing on and off like 10 different times, just so I could briefly experience the Neo in RGB, finally. But it's so depressing that this PVM is broken, so I can't really play it.

I also recently got a 3DO rgb mod done, by acem77, and I had him just put a 9 pin connector on the back of it, with the pinouts for my 1084. (I have a pass through cable that I was going to use). So I tried that on my 1084, and just like with the Geo, the picture rolled. It didn't bounce too much, like the Geo was doing, it just rolled. The Geo kinda rolled and bounced. Anyways, so while I was seeing if the Geo would work on the PVM, I  figured that I might as well also try the 3DO in RGB. It worked great, just like the Geo!!!. Man, it's pretty amazing to see Crash N Burn in RGB. (just happened to be the game that I tried) Again, though, I can only play the thing for 2 minutes until my PVM's picture zaps out.


Now, you might wonder, "Why not get the PVM fixed?" Well, I tried that. I took it to this place, they said it was fixed like 4 times, and each time I took it home and the next day the picture would zap out just like before, so ultimately they couldn't fix the thing. Even if it did work, I unfortunately don't have a good place to put that 27 inch Monster. But my Commodore 1084 works perfectly for me, being such a small monitor, it works perfect in my computer room, and thats where I play my systems in RGB. I'm not sure why just the Neo and 3DO don't work on that 1084, but everything else I have does. I have Jaguar, 32X, TurboDuo, Sega CD, Genny, SNES, modded N64, Saturn, PS1, Dreamcast you name it. They all work absolutely fine on my 1084, but for some strange reason, the Neo-Geo and 3DO just don't work on that 1084. The picture just rolls.


Anybody got any ideas? I'm going to be watching Ebay to try to find a smaller Sony PVM that will fit in my computer room, and I've been watching for a certain model #, but I can't find one that is for sure working at a half-way decent price, especially when shipping is factored into the equation.  I really wish I could just use my 1084 with "all" my systems, but I'm not sure if I'll ever be able to.


Does anybody have any idea why like 10 different consoles of mine work fine in RGB on my 1084, but the Neo-Geo and 3DO don't? Is there some chip or something that needs to be in my Neo-Geo cable or my 3DO cable so that my 1084 monitor will be able to display it without the rolling picture?

[kripp]

I read this post last night and thought nothing about it... untill 6am this morning. Come to think of it, there are certain consoles that "roll" on my 1084S-D aswell.

The first one that comes to mind is the Nintendo 64. I've built a RGB cable for the SNES which has the same pinout for the Nintendo 64 (yes I did modify the Nintendo 64 PCB), but when plugged into the Nintendo 64 all it does is "roll" the picture.

The second console that has the same issue is the Dreamcast, I wired up an RGB cable for it last night and it does the exact same thing. Although I have yet to try and add a resistor to the sync line, this has solved display problems with other consoles.

All of my other consoles that support RGB output work just great on this monitor, just these two (so far) have problems.

I'm not sure why certain consoles do this on these Commodore 1084S-D monitors, but atleast I'm not the only one with this problem.

Thanks.

[NFG]

The 1084 monitor can be really flaky.  The one with the 9-pin D-sub connector is the weaker of the ones I've owned, it tends to give unpleasant results with a lot of sources.  I never did solve it, though since I also had another 1084 without the problem I never tried very hard.

[RARusk]

After looking over your post Anthony it sounds like the sync on both the NeoGeo and 3DO have a little too much juice on them and the 1084 is sensitive to it.

You could try to set up one of the video lines of the Neo Geo (green preferably since it shows up better) and put resistors on the sync line until the picture stabilizes (if it does). Start with the often used 75ohm resistor and work your way up. If the picture fixes itself then try it with the 3DO. If it works on that then try one of your other consoles. If it doesn't interfere with any of your other consoles then you could make a simple little dongle you can keep permanently attached to the 1084 and hook up your consoles to the dongle.

[kripp]

I tested the sync line output voltage on a few of my consoles, this is what I've come up with... (I tested from the end of my dongle, not from the console AV port)

Dreamcast: 0.82v (will not sync at this voltage)
SNES: 2.22v
Saturn: 3.32v (Can't remember if I added the resistor or not)
Neo Geo CD: 4.50v (resistor on sync line)
Genesis model 1: 4.38v (resistor on sync line)

* Not 100% on the value of the resistors, I just tested a bunch untill one worked!

The Neo Geo CD and Genesis model 1 would not sync without the resistor, I have a few other consoles with the same resistor setup but did not test them.

I guess with the 1084 the sync line voltage needs to be within a certain range for the image to sync. Perhaps another 1084 owner could test their consoles and see what results they get.

Would it be possible to feed the sync line a +5v source and step it down a notch with a resistor to get the voltage within range for the 1084?

Thanks.

[viletim!]

kripp,
Sync is actualy a signal, not a DC voltage, so a multimeter can't tell you much about it.


I've got the circuit diagram for a daewoo 1084 and it has a strange looking sync input circuit...I suppose it's to auto detect the sync polarity. If the sync signal source isn't up to the task of driving in then a resistor or capacitor in series can help a bit but it's a really dodgy solution. A better idea is to just buffer the sync signal (make it...stronger, more defined, more progressive) with a digital gate or two. Something like a 7407 with a stiff pullup resistor and all the gates wired in parallel. Or perhaps the more common 74ls04, again all wired in parallel (maybe one before series if the monitor doesn't like positive sync).

Maybe the composite sync input on these monitors is generaly too insensitive....the commodore computers all used either sync on video or seperate H/V sync so perhaps nobody noticed/cared?

If anybody wants to pull their 1084D apart I've got some ideas for simple circuit modifications to make it work better.

[kripp]

I have tried feeding the sync line a +5v source and then bringing it down or into range with a resistor, it does work some what. The image from my Dreamcast without the added voltage is very scrambled, you can make out the colors but no image. With the added voltage and a resistor I can get the Dreamcast to display a very crisp image, but it still rolls asif the vertical hold is off.

If I can find the right resistor value then this solution should be fine for me, no need to pull apart my 1084 just for Dreamcast RGB. Out of all the consoles I own with RGB output, only the Dreamcast and Nintendo 64 give me this problem with this monitor.

viletim!,

I would be willing to pull the 1084 apart and test a simple circuit or two, let me know what ideas you had in mind.

Thanks.

[Midori]

If I can find the right resistor value then this solution should be fine for me, no need to pull apart my 1084 just for Dreamcast RGB. Out of all the consoles I own with RGB output, only the Dreamcast and Nintendo 64 give me this problem with this monitor.

I assume you know that the N64 doesn't have naitive RGB output?

[viletim!]

kripp,

Well first I'd need to know what IC I202 is. My circuit calls it a 74LS06 but I'm sure it's wrong (I think it might be an '86).