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45 lines
1.7 KiB
45 lines
1.7 KiB
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\documentclass[11pt]{article}
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%Gummi|065|=)
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\usepackage{graphicx}
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\usepackage{caption}
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\title{\textbf{Commodore 1902A Repair}}
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\author{Steak Electronics}
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\date{}
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\begin{document}
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%\maketitle
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\includegraphics[scale=0.4]{../pics/DSCN1699.JPG}
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\captionof{figure}{Commodore 1902A 14'' CRT Monitor}
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\section{Overview}
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The goal is to repair an old Commodore computer monitor. This particular monitor, the 1902A has two inputs. One for composite, and one for a mode which the C128 must run in, in order to produce video output for C64 compatibility mode or something. I'm not really sure. (todo). This means RGBI input must work.
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Currently, the monitor has errors on both RGBI input, as well as composite input. This means that the errors are likely common to both signal paths.
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\tableofcontents
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\section{Work Log}
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I picked up an old HP TV service manual (6945A) for this project. I am not knowledgable about televisions, but the more I read, the more I think I can handle this. I have also the manual for the monitor, though it is quite a bit sparse, comparably.
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Quite a bit of the Commodore 1902A TV circuitry (H sync, V sync, etc) is in a few ICs.
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The waveforms in the Commodore manual were created with a (standard?) NTSC test signal, the \textbf{10 bar gated rainbow pattern signal}. I am currently researching how to generate that myself, without forking out the cash for a video tester (Cheapest I saw the other day was \$70. I wouldn't pay more than \$20.
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From a brief search, most people have only setup rough test signals with uCs that do either NTSC or PAL, but not necessarily the full 10 bar gated test signal, instead only a passable working signal, to verify video output.
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\end{document}
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