Thread View: net.micro.atari
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Started by Bill Dippert
Mon, 13 Jan 1986 16:42
XL/XE Monitor Output Jack Mods, Etc.
Author: Bill Dippert
Date: Mon, 13 Jan 1986 16:42
Date: Mon, 13 Jan 1986 16:42
63 lines
2899 bytes
2899 bytes
Has anyone tried the solution for the lack of chroma in the 800XL that
was published in the February ANTIC i/o board column? Essentially it
says that the chroma output is at the emitter of Q5. You need to connect
a 200 ohm resistor from the junction of R67 and R68 to pin 5 on the monitor
connection. Credit for this goes to the Chicagoland Atari Users Group.
R67 R68
_____ __.__ _____
^^^^^ | ^^^^^
|
|
>
> 200 ohm
>
>
|
|
|
pin 5
Note: resistors R67 and R68 actually are next to each other and not back
to back as this diagram would indicate. I have intalled this on my 800XL
and the picture I get on my C*******e 1702 monitor is identical to that
of my 130XE. (I would suggest to install this on the bottom side of the
board. It is easier to get outside of the shield that way and also it
is easier to solder.)
Question: the diagram for the 130XE shows --
pin 1 composite luminance
pin 2 ground
pin 3 audio output
pin 4 composite video
pin 5 composite chroma
-- the 800XL still has one pin not used (I think pin 4), what does this
mean? Should this remaining pin be connected? If so, to what?
Then on the 1200XL, I find that pin 5 is not connected to anything, but
pin 4 is. Is pin 4 composite video on the 1200XL and if so, should I
connect pin 5 to pin 4 or to something else (on the 1200XL)?
I find it hard to imagine that the 130XE requires five pins connected
and that the 800XL and 1200XL only require four pins connected. And not
the same four to boot!!!
By the way the pin configuration (per the 130XE manual, as looking at
the connector on the computer is:
|_|
3 . . 1
5 . . 4
.
2
[Only Atari would not number these pins consecutively!]
--Bill--
tektronix!tekigm2!wrd
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We still need to split to net.micro.atari and net.micro.st!
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Re: XL/XE Monitor Output Jack Mods, Etc.
Author: Steele.Henr
Date: Wed, 15 Jan 1986 17:49
Date: Wed, 15 Jan 1986 17:49
7 lines
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>>[Only Atari would not number these pins consecutively!] The numbering scheme used on the Atari Video Output connector is a standard 5 pin DIN plug with standard 5 pin DIN plug numbering so you can't blame Atari just the Germans. ---JOHN--- Xerox Corp.,Roch.,N.Y.
Re: XL/XE Monitor Output Jack Mods, RGB &Etc.
Author: JRCooper.PA
Date: Wed, 15 Jan 1986 18:29
Date: Wed, 15 Jan 1986 18:29
26 lines
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2176 bytes
Bill, I can't answer your question about the 800 XL but I can tell you that you don't need all of the video signals that ATARI provides at the connector to make a monitor work. All of the Atari computers deliver Composite video on one of the five pins...I was not aware that they might be machine dependent regarding the actual pin number. If someone would want to use a monochrome monitor then a luminace only signal is available. ***The Pin numbers found on the 5-pin DIN connector have been decided by the DIN (German Standards committee) so don't blame ATARI for that one. An interesting ramification of the signals provided by the 130XE is that a cheap RGB decoder could be built to derive the component colors from the combination of composite luminance and composite chrominance. I haven't fully investigated this yet but you would need a sync stripping circuit, a couple of band pass filters to separate the colors and maybe a few delay lines. RCA makes a few interesting IC's (CA3130--33) that take luminance and chroma signals an turn them into R-Y, B-Y, and G-Y where Y is the luminance portion. Those chips are designed for decoding broadcast signals inside your TV set. Beyond that you will need to then transcode the R-Y,etc. (You don't need the G-Y) signal into RGB for RGB monitors. As I actually get into doing this processing I will post a more coherent description to the net. This is the only way to get RGB out of an atari since the NTSC composite video is computed a a composite signal. Jim Cooper
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