Millipede help. Colors all bonkers.

mochaman

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I acquired a Millipede board today. It played fine for an hour or so. Then the colors went bonkers, almost to a negative look. I have reseated all chips twice. Tried different board in machine and colors are there so I know its a board thing. Any ideas as to what would/could cause this to happen? I've also tried it without filter board but no change.
 

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Yes. No errors on rom/ram. Here is pic of color test screen.
 

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I've had similar colors issues in the past. They have all been bad color ram. Either one or more failed rams or a failed part in the color ram address section of the board is my guess. Self test won't show these rams as being being bad since it doesn't test them.

Brian
 
That figures. 3 boards and none flawless. Oh well. Thanks for the input.
 
if you want to sell me your 3 broken boards. I'll buy them. I fix centipeds and millipedes and other atari games. I would also consider trading for a working millipede.

PM me if your interested
-brian
 
Yes. No errors on rom/ram. Here is pic of color test screen.

How do you get that screen in Millipede? The only one I've seen is this one:
milli-badpokey.png


And looking at the bottom of this page, your pics kinda look like the "BAD 5R" pics, maybe?

http://www.brasington.org/arcade/products/cm/trouble.shtml
 
Self test won't show these rams as being being bad since it doesn't test them.

Self test won't report them, because the CPU can't read them... their outputs are only connected to the video output circuitry; not the data bus.

But the self-test procedure DOES describe cycling thru all 16 colors, for both the background and object colors. If you don't get all 16, that's an indication of bad color RAM (per right side of Figure 6 in the manual).
 
How do you get that screen in Millipede? The only one I've seen is this one:
milli-badpokey.png


And looking at the bottom of this page, your pics kinda look like the "BAD 5R" pics, maybe?

http://www.brasington.org/arcade/products/cm/trouble.shtml
To see self-test screen two, set the self-test switch to off, then press the auxiliary coin switch and set the self-test switch to on together. Pressing the coin switch again brings up screen three ( for convergence).
 
Self test won't report them, because the CPU can't read them... their outputs are only connected to the video output circuitry; not the data bus.

But the self-test procedure DOES describe cycling thru all 16 colors, for both the background and object colors. If you don't get all 16, that's an indication of bad color RAM (per right side of Figure 6 in the manual).

Where is figure 6 in manual? Don't see it in mine.
 
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