Found an LCD monitor that works

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rcamp48
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Found an LCD monitor that works

Postby rcamp48 » Fri Apr 06, 2018 6:07 am

I just found an LCD TV that works perfectly with my Atari STE AV output, its a Citizen 32CL710A flat screen TV about 15 years old, still works really good but for some reason I cannot get the VGA to work properly with an Atari ST to VGA cable. The resolution its putting out is 1280 by 900, and I have my TV set to widescreen , (could be the problem...).. anyways any experts around ?

Russ

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spiny
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Re: Found an LCD monitor that works

Postby spiny » Fri Apr 06, 2018 9:45 am

To use VGA, the monitor needs to support Horizontal refresh rates of 15kHz, which hardly any monitors do.

The specs for yours aren't 100% clear, but it doesn't look like its compatible:

http://cwdlimited.com/citizen/manuals/3 ... Manual.pdf

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spiny
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Re: Found an LCD monitor that works

Postby spiny » Fri Apr 06, 2018 9:46 am

This is a handy list of monitors that have been tested:

http://15khz.wikidot.com/

bear in mind it's not an exhaustive list, I have a monitor that works with low res VGA that isn't on that site, yet.

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Foxie
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Re: Found an LCD monitor that works

Postby Foxie » Fri Apr 06, 2018 3:06 pm

rcamp48 wrote:I just found an LCD TV that works perfectly with my Atari STE AV output, its a Citizen 32CL710A flat screen TV about 15 years old, still works really good but for some reason I cannot get the VGA to work properly with an Atari ST to VGA cable. The resolution its putting out is 1280 by 900, and I have my TV set to widescreen , (could be the problem...).. anyways any experts around ?


Is that a monochrome VGA cable, or colour? Monochrome mode is very close to standard VGA, it will work on many monitors (albeit with scaling blurring on many LCDs).

If you want to use colour, the best strategy is to use an RGB SCART cable. The quality will be as good as VGA, but all SCART sockets will accept a 15kHz signal without trouble. Using composite or RF will degrade the picture quite a lot.

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olivierg
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Re: Found an LCD monitor that works

Postby olivierg » Fri Apr 06, 2018 10:28 pm

Hi,

I have ordered this monitor this week and recieved.
Works on all ST Resolution with adaptor: viewtopic.php?f=15&t=30521

https://www.befr.ebay.be/itm/NEC-LCD197 ... 2749.l2649

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Olviier
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siriushardware
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Re: Found an LCD monitor that works

Postby siriushardware » Tue Apr 10, 2018 4:57 pm

spiny wrote:To use VGA, the monitor needs to support Horizontal refresh rates of 15kHz, which hardly any monitors do.

The specs for yours aren't 100% clear, but it doesn't look like its compatible:

http://cwdlimited.com/citizen/manuals/3 ... Manual.pdf


The way I read the OP's original statement, he is using an AV (composite) cable for low and medium res which is working fine, and he is having trouble getting his ST to work in the mono mode with an ST to PC/VGA input cable, which should normally work.

The one monitor I had trouble with in this regard had 75 ohm internal termination resistors from Vsync down to ground and and Hsync down to ground inside the monitor, on the PC / VGA input. That was too low a resistance for the Vsync and Hsync outputs on the ST to drive and so the sync signals virtually disappeared when the ST's output was connected to the monitor's sync inputs. The message reported on the monitor was that no input signal was detected, by which it meant it could not see any sync input.

I could probably have fixed it by raising the values of the internal resistors to 470 ohms or 1K without breaking PC compatibility, but I just used a different monitor instead.

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spiny
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Re: Found an LCD monitor that works

Postby spiny » Wed Apr 11, 2018 10:06 am

siriushardware wrote:
spiny wrote:To use VGA, the monitor needs to support Horizontal refresh rates of 15kHz, which hardly any monitors do.

The specs for yours aren't 100% clear, but it doesn't look like its compatible:

http://cwdlimited.com/citizen/manuals/3 ... Manual.pdf


The way I read the OP's original statement, he is using an AV (composite) cable for low and medium res which is working fine, and he is having trouble getting his ST to work in the mono mode with an ST to PC/VGA input cable, which should normally work.

The one monitor I had trouble with in this regard had 75 ohm internal termination resistors from Vsync down to ground and and Hsync down to ground inside the monitor, on the PC / VGA input. That was too low a resistance for the Vsync and Hsync outputs on the ST to drive and so the sync signals virtually disappeared when the ST's output was connected to the monitor's sync inputs. The message reported on the monitor was that no input signal was detected, by which it meant it could not see any sync input.

I could probably have fixed it by raising the values of the internal resistors to 470 ohms or 1K without breaking PC compatibility, but I just used a different monitor instead.


Thats a good point, I read it as using it for Colour modes, which probably won't work. but it should work fine for Hi-res

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1024MAK
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Re: Found an LCD monitor that works

Postby 1024MAK » Thu Apr 12, 2018 1:45 pm

Here I am talking about using the high-res. monochrome mode.

With LCD monitors, it appears to depend on how tolerant the design of circuitry is to out of specification VGA signals.

This applies also to the more complex CRT monitors.

Some years ago when I tried a number of my ST's with the variety of CRT and LCD monitors that I had, I found different results depending on which STFM or STE I connected up 8O

Some monitors were perfect, some LCD monitors worked, but the picture was not very good due to the banding that you get due to the frequency the monitor circuitry samples at. Others were just plan unhappy with the video signal from the Atari.

Mark
Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (nearly forgot the Psion's)


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