Scott Lawrence (jerronimo) wrote in classicamiga,
Scott Lawrence

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Amiga 1000 Rebuild

So I decided to revive my Amiga 1000. Back in college I re-grounded and replaced the PALs on the daughterboard, but I did a poor soldering
... namely, I took a shortcut which worked for a while... some of those center pins never saw any
solder. Over time, they corroded and it all stopped working. The last time before this week that I actually
had it working was bout 8 years ago at this point.

I put up loads of pics for those interested.

In any event, I've encountered a problem. I soldered the PALs directly to the board, since I couldn't find any sockets at home, which works,
as I
can get it booting now. (The floppy
drive being vertical thing no longer is true. It works horizontally now.)

Here's the problem...

It seems like some colors aren't being generated properly. all 12 levels of Red look perfect. green and blue do this weird stepping thing. Rather than the effective values being "0 1 2 3 4 5 6 7 8 9" for example... it's treating them as "0 1 0 1 0 9 8 9 8 9" It's like one of the middle bits of the value are being ignored. I looked around on the net, and found reference to a color issue being a result of a bad 74HC244 in the video circuitry, so I think this might be related. I tried a different Denise, but to no avail.

here's a movie that demonstrates the issue:

Does anyone have any clues for me?
Tags: amiga 1000 repair
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