About PCB brightness issues and video amplifiers

[dpful]

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Does anyone know:
If I put one of these in the JAMMA line, would it take any PCB's I had that were a little dimmer than others and brightn them all to a standard level?
Or would it make them all super bright and still different brightnesses relative to each other?

Some of my monitors are much less sensitive to different PCB brightnesses- I was hoping that it was because they had circuitry that brought everything up to a standard level before displaying-- and I was hoping that this was the part (to use with my more sensitive monitors so I could switch games with less hassle).

[dpful]

I got the amp in the mail and tried it out on some dim PCB's. It just made the colors very very dark, almost black, while the pcb still put out an overly low contrast signal-- everything was still a little gray, there was no increase in real "black" areas.

So the idea was not successfull. Apparently, a higher voltage output from the board affects color saturation, but not contrast, so you end up with a dim, dark image.

What does effect contrast? I've also got a sega genesis that puts out jamma, and it's image looks great, but just low contrast. I remember hearing that when you hook up certain home systems and they give a low contrast image, you can put certain capacitors on the rgb lines and it will fix it. Does anyone know about that? What kind of capacitors or how it works?

[neorichieb1971]

My sega Genesis 2 was overly bright. I needed 3 75ohm resistors and put them on the RGB lines. Well I only had 100ohm resistors, but it still worked, maybe a tad darker than it should be though.

If the signal is dark to begin with.. Like my flying sharks was. On that I had a cabinet and just turned up the contrast and brightness.

Because superguns are built differently its impossible to diagnose the problem with the information you gave.

What PCB's are dim? What connection cable, transcoder are you using? Does your SG have RGB pots?

[rtw]

I got the amp in the mail and tried it out on some dim PCB's. It just made the colors very very dark, almost black, while the pcb still put out an overly low contrast signal-- everything was still a little gray, there was no increase in real "black" areas.

Looks like this amplifier is for boosting a low level VGA signal to RGB
levels so it cannot be used on a proper PCB which is already
outputing RGB levels.

What games are dim and on what monitors do you run them on ?

Supergun or Cab ?

rtw

[D]

Dumb question. I do not understand what this thread is about. You can turn contrast and brightness on or off on a monitor tv. So why is this a problem? I can imagine if the rgb lines give too much brightness/contrast it might be too much for the signal to handle and you will get maybe unwanted effects or if the rgb lines give to little brightness/contrast you will get too much noise, because everything needs to be amplified by the tv/monitor. As far as getting a device that will normalize the brightness/contrast levels... so you will never have to switch contrast/brightness levels on your tv/monitor, that would be great.
BTW, do monitors/tv's exist that readjust the screen so that every resolution (pcb's have different resolutions) gets displayed full screen. I'm not talking 15/24/31 multisync stuff, I'm talking about all different 15 Khz resolutions. I remember that I made a generic scart to jamma adapter for use with every console that has a scart lead and that I had to turn contrast way up. It was the least of my problems. I always have trouble with getting the image full screen!

[dpful]

I was looking for a device that would normalize rgb levels so I don't have to adjust all the time.
Also looking to see if there were any easy hardware fixes (caps on the lines and such) that would effect contrast and/or brightness. Contrast, mostly, since resistors seem to effect the brightness.

Noteable dim boards are ibara, vasara 2, r-type leo, some others all on random different hardware I think.
I'm running them in cabs.
My nanao 27" (I believe) in my taito egret is very sensitive to this, my other monitor (can't remember the make) is less sensitive, so I assume it normalizes the signal quite a bit internally.

[rtw]

Noteable dim boards are ibara, vasara 2, r-type leo, some others all on random different hardware I think.
I'm running them in cabs.
My nanao 27" (I believe) in my taito egret is very sensitive to this, my other monitor (can't remember the make) is less sensitive, so I assume it normalizes the signal quite a bit internally.

What kind of monitor do you have exactly ?

Which PCB's do you consider not dim ?

I had a similar problem on my Hantarex Polostar 25" and it turned out
that I had to move an impedance jumper.

rtw

[Stefan_L]

My monitor (philips cm8833-II) also displays R-Type Leo very dim evem at monitors highest contrast... actually all my IREM M92 games are like that, M72 games are also a bit dim not as much as M92 though.
I guess the RGB signal from the PCB is weak?

[dpful]

Noteable dim boards are ibara, vasara 2, r-type leo, some others all on random different hardware I think.
I'm running them in cabs.
My nanao 27" (I believe) in my taito egret is very sensitive to this, my other monitor (can't remember the make) is less sensitive, so I assume it normalizes the signal quite a bit internally.

What kind of monitor do you have exactly ?

Which PCB's do you consider not dim ?

I had a similar problem on my Hantarex Polostar 25" and it turned out
that I had to move an impedance jumper.

rtw

It's a NANAO series 8 model MS8
Most of my other boards have a consistant brightness. Donpachi, dodonpachi, strikers 1945's, g-net, pgm, cps2, all same bright look. (another one that's really dim is Kaneko super nova).

does that monitor ring a bell? That's what is says on the tube (I couldn't get a good look at the chasis). That would be great if it was a jumper.
Again, my other monitor seems quite versatile at displaying a consistant brightness.

[rtw]

I asked a friend of mine who is quite savvy with monitors.

Tell him to just ground his signal properly. And, he will never get his RGB-signal equalized in a nanao RGB-monitor. Not even a television does that. The reason why his Sega home console displays a great picture is because it has common gnd:s in everything. He needs to review his jamma-connector, nothing else.

It's usual that Konami games, especially the GX system, has a higher brightness level. That's why we have adjustment pots.

And the caps at the end of a RGB-cable are not for equalizing/normalizing anything. They're just there to eliminate any picture disturbance caused by the cable movement, like little brother tripping on it etc.

rtw

[oxtsu]

My monitor (philips cm8833-II) also displays R-Type Leo very dim evem at monitors highest contrast... actually all my IREM M92 games are like that, M72 games are also a bit dim not as much as M92 though.
I guess the RGB signal from the PCB is weak?

Air Buster is one I've encountered with an unusally dim image.

I asked a friend of mine who is quite savvy with monitors.

This friend of yours knows his stuff, I agree. :)

[D]

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