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Old 14 December 2017, 22:14   #1
Devlin
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Amiga passive DB23>VGA (15khz modes)

I can VERY HAPPILY confirm that it works on the Acer K242HYL.


This is a standard 15khz "PAL" mode.

The image quality is crap because I lack good soldering skills and the connections are going to be complete arse, but I can at least confirm that there's a modern(still sold today) display that can handle the Amiga's resolutions.

I used the information from this image to make my cable
<image deleted to avoid breaking amigas>

Last edited by Devlin; 19 December 2017 at 00:48.
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Old 14 December 2017, 23:20   #2
Daedalus
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It might be the lack of screening and the questionable ground connections in that diagram rather than your soldering skills that cause that sort of image problems, but good to know another model that works!
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Old 14 December 2017, 23:30   #3
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Quote:
Originally Posted by Daedalus View Post
It might be the lack of screening and the questionable ground connections in that diagram rather than your soldering skills that cause that sort of image problems, but good to know another model that works!
I'm not that confident in my soldering skills but I'm glad someone is!

I spent a lot of time looking for the datasheet for this display and it didn't say anywhere that it supported these modes so I figured I was pissing in the wind(figuratively) but I was especially surprised my DELL display (just out of shot) spat an out-of-range error because I thought it was the more compatible display.

The K242HYL is a really nice monitor (hence it being my primary PC display) and goes for about £120 on amazon.
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Old 15 December 2017, 00:02   #4
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Be careful with the diagram. Pin 22 on Amiga is actualy +12V, so you risk damaging your equipment. For ground pins on Amiga side use 16-19.
Anyway happy to see another monitor compatible I will include it in my list Can you check whether it can change aspect from 16:9 to 4:3?
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Old 15 December 2017, 00:50   #5
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Quote:
Originally Posted by amigoun View Post
Be careful with the diagram. Pin 22 on Amiga is actualy +12V, so you risk damaging your equipment. For ground pins on Amiga side use 16-19.
Anyway happy to see another monitor compatible I will include it in my list Can you check whether it can change aspect from 16:9 to 4:3?
It doesn't sadly.

Is there a better schematic for this kind of cable? It'd be trivial for me to de-solder my hack job and redo it with better cables.
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Old 15 December 2017, 00:57   #6
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Try this: http://old.pinouts.ru/VideoCables/am...b_pinout.shtml
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Old 18 December 2017, 18:59   #7
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Amiga video connector pins 11 and 12 are hsync and vsync, but those lines are unbuffered, leading more-or-less directly to the Agnus chip. If connecting to those you should really buffer the signals.

A better option would be to use Amiga pin 10 which is csync (composite sync) instead. That line is buffered already, and your monitor will probably work if you just connect it to the monitor's hsync pin (pin 13 of the VGA connector). Leave the monitor vsync pin (pin 14) unconnected.
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Old 18 December 2017, 19:46   #8
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I'm not using the cable now on account Bad Things have happened to my amiga because of it.

Gonna just buy an adapter in the future for the 1200 - repairing the RGB/SCART connection is my priority right now.
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Old 18 December 2017, 23:00   #9
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If you can, please remove the first post schematic, to ensure other users do not make the same mistake.
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Old 19 December 2017, 00:48   #10
Devlin
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Quote:
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If you can, please remove the first post schematic, to ensure other users do not make the same mistake.
Done.
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Old 19 December 2017, 01:43   #11
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Quote:
Originally Posted by mark_k View Post
Amiga video connector pins 11 and 12 are hsync and vsync, but those lines are unbuffered, leading more-or-less directly to the Agnus chip. If connecting to those you should really buffer the signals.
This is true, however those sync lines tend to be fine with more modern displays with very high impedance inputs. Also, it's more the big box Amigas that have trouble dealing with excessive loading on the sync lines, making them think they have a genlock attached. I've yet to find a monitor that caused a problem with an A1200, though of course I've only tried a tiny number of models. Buffering the signals is pretty trivial however, and it's what the original Commodore adaptors did.

Quote:
A better option would be to use Amiga pin 10 which is csync (composite sync) instead. That line is buffered already, and your monitor will probably work if you just connect it to the monitor's hsync pin (pin 13 of the VGA connector). Leave the monitor vsync pin (pin 14) unconnected.
Most modern (as in, built in this century) monitors will go into standby mode with a loss of either sync signal.
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