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Offline DmasterTopic starter

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Commodore 1902a monitor
« on: February 13, 2008, 10:04:41 AM »
Hello all.  My brother went to visit my country (Puerto Rico) there I had left many years ago a commodore 1902 monitor which I never used.  Well today het got back home and I asked him to bring this with him.  I powered it on and it works!  Now, there was a cable that came with it which I connected to my amiga and to the monitor but I get no video.  I am able to use it with my a520 and it looks ok.  I am not sure if the cable I want to connect directly to my amiga is any good.  or I maybe using the wrongs settings on the switches on the back or front of the monitor.  Does anyone know where I can get a working cable for it to be able to use it directly to the amiga instead of using the A520?  And also, does anyone know where I can get an online manual for it? Thanks.  
 

Offline banzai

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Re: Commodore 1902a monitor
« Reply #1 on: February 13, 2008, 01:21:53 PM »
I don't have any user manuals, but I have the service manual. According to that, the 1902 happens to be a combo Composite Video or Digital (CGA-type) RGBi monitor.

If you have a continuity tester handy, I'm sure you'll find that the cable you're using is tapping pins 3, 4, and 5 on the Ami's RGB port (that's the Analog RGB, which gives you the 4096 colors). What you need is the cable that'll use the Digital output pins of 6, 7, 8, and 9. Digital RGB will allow three bits (R-G-B) for color, and a fourth bit to turn on/off the Intensity (i), giving you 16 colors. Actually, now that I think about it, this is more akin to the old "Tandy" graphics, as CGA only gave you four, and EGA had higher resolution.

If you are handy enough to make your own cable, then you'd wire it up as:

1902 8-pin DIN to DB23F

1 -> N/C
2 -> 9 (DRed)
3 -> 8 (DGrn)
4 -> 7 (DBlu)
5 -> 6 (Di)
6 -> 19 (Gnd)
7 -> 12 (VSync)
8 -> 11 (HSync)

(Horizontal and Vertical sync signals are combined internally of the 1902 to get a composite sync.)

Switches on the 1902 should be something like:
CVS/CVBS = Composite
LCA = Luma/Chroma/Audio (Split composite)
RGBi = Digital RGB
VCR = Switches in an extra comb filter for video playback
Green = Monochrome using green gun only

banzai
 

Offline Jope

Re: Commodore 1902a monitor
« Reply #2 on: February 13, 2008, 01:33:05 PM »
Just don't be disappointed with the lack of colours you get with RGBi.
 

Offline chiark

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Re: Commodore 1902a monitor
« Reply #3 on: February 13, 2008, 02:08:00 PM »
You could convert a 1901 to analog RGB...  I don't know if it's possible for the 1902 tho

I don't know the details unfortunately, but I had mine done.
Celebrating 21... no, make that 27... years of Amiga use
 

Offline TDScompute

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Re: Commodore 1902a monitor
« Reply #4 on: February 13, 2008, 03:16:03 PM »
Was this more for the Commodore 64 & 128, as opposed to the Amiga line? I think so... Or maybe even Commodores line of PC's. I have one of these, but I don't think I have ever used it. I plan on using it just for composite output.
 

Offline TjLaZer

Re: Commodore 1902a monitor
« Reply #5 on: February 13, 2008, 03:23:10 PM »
Most early 1902's worked with the Amiga, so Amiga users bought it instead of the 1084 series since they were cheaper. But Commodore soon caught wind and crippled the analog RGB in them in later models!
Going Bananas over AMIGAs since 1987...

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