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Monte Carlos
Registered: Jun 2004
Posts: 358 |
C128D gets out of sync, after issuing color6,x with x>1 in 80 col mode
Recently i set up my c128D again, instead of my c64. I got a 9 pin 1:1 cable to be able to use the 80 col mode of the c128D. The cable beeing attached to my 1084S monitor, which does not have a din plug for the RGB signal.
The 80col mode itself works, as far as i do not change the background color of the text characters. The signal quality is very good, i have a sharp, stable image. As soon as i issue the command color6,x with x>1, the screen gets out of sync like if one has deadjusted the vsync with the knob at the back of the monitor and i do not know why. After issuing color6,1 the image is stable again. The problem also occurs with several other programs, which change the background color of the VDC text characters. The c128 system information returns 64k VDC, so this is probably not an issue due to VDC Ram limitations.
Monte Carlos
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Skate
Registered: Jul 2003
Posts: 494 |
my problem is worse. i tried to build a monitor cable myself and i had that vsynch problem with my C128D (independent from backgorund color etc.). since i'm very lame at hardware stuff, i bought a cable from Vesalia Computer and it didn't work, either. since both cables had the same result, i blamed my 1084S. After trying with the 3rd 1084, i figured out both monitors and cables were ok but i had a problem at C128D side. I examined the vsynch pin and there is no "visual" problem but as i said i'm not good at electronics and i don't know how to test/repair the problem. The answer of Monte Carlos' question may help me as well. What can go wrong at C128D side about vsynch? A loose contact at circuit? A burned component? |
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Monte Carlos
Registered: Jun 2004
Posts: 358 |
Interesting, that you have a close problem. Have you tested another c128 with your monitors and cables? Else you cannot conclude your monitors and cables were ok.
I never did much with my 128, except watching "Risen from Oblivion" some years ago. This demo at least worked perfectly back then. Does that demo work with your c128?
I will try that again, if it fails now. Perhaps something happened to my 128 in the meantime.
Also, at this time i did not fiddle around with the color command of basic 7 and i also did not test any c128 specific programs. So, it is possible, that the problem was there from the beginning and i did not recognize it.
Monte Carlos
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
I think this problem is caused by the monitor, probably some aged capacitors or similar.
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zyga
Account closed
Registered: Mar 2009
Posts: 6 |
Quoting Monte CarlosI got a 9 pin 1:1 cable to be able to use the 80 col mode of the c128D. The cable beeing attached to my 1084S monitor, which does not have a din plug for the RGB signal.
Actually connection to pin7 is not necessary, as RGBI needs separate VSYNC/HSYNC. Try to disconnect this, and report results. |
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Skate
Registered: Jul 2003
Posts: 494 |
i couldn't find another C128 to try, otherwise i'd choose the easier path to test.
i'm 99% sure it's C128 related since i have two cables (one done by me, one bought from the net) and three 1084 monitors. all combinations give me exactly the same result. result is vertically sliding screen in 80 column mode. it's my C128D, i know. i just don't know how to fix it. actually i didn't care about it that much until seeing this topic. i have some hardware guru buddies who can fix my C128 for me. but if there is something obvious about this problem, i'd like to give it a try myself... so, my hw guru buddies have to double their efforts to fix what i messed up. :) |
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Monte Carlos
Registered: Jun 2004
Posts: 358 |
@Zyga: I think about a non destructive solution of disconnecting pin7. Will try the next days;)
Can you explain how pin7 is related to vsync/hsync?
If it is not connected anyway, why bother?
Yours Monte Carlos
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zyga
Account closed
Registered: Mar 2009
Posts: 6 |
There are several versions of 1084S. For example mine has DB9 connector for RGB and switch described as "Analog/TTL".
- analog RGB (for example Amiga), expects composite sync on PIN7 (CSYNC)
- TTL = digital RGB (C128, IBM CGA), expects separate horizontal/vertical synchronization signals on pins 8/9.
In C128 pin7 is connected to monochrome video signal (as in Amiga 500 on Video Out) = luminance + composite sync.
In my opinion Analog/TTL switch should connect/disconnect this (7) pin, but who knows ? Better check ;)
http://www.hardwarebook.info/C128_RGBI
http://amiga-hardware.com/showhardware.cgi?HARDID=849 |
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ready.
Registered: Feb 2003
Posts: 441 |
on my 1084s with DB9 I had to resolder the connector since its only supports are the soldered pins on the monitor motherboard, so plugging in and out wears the solder joints in the long (short?) run. |
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Monte Carlos
Registered: Jun 2004
Posts: 358 |
I don't believe it. The bit 7 trick worked out!
Proves, magic number 7 is the solution for everything.
Monte Carlos |
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zyga
Account closed
Registered: Mar 2009
Posts: 6 |
Nice to hear ;) |
