Figured out WHY lockups, now to figure how to fix!

[Wayne]

Well, I think I figured out why my Dreamcast locks up and now I just need to figure out how to fix it.

I was able to play some games on my DC after it ####ted locking up by turning it on its side with the fan vent UP (controller ports forward), and a large box-fan blowing on the bottom of the game. I played a couple of problematic games after I ####ted locking up...

The problem seems to be overheating of the several LSI chips on the mainboard. Two of the LSI chips (big square chips) have a sort of grey coating on them that looks like it may be thermally conductive. These chips are directly under the shield which has another heavy piece of metal riveted to it (between the mainboard and the shield).

That heavy piece of metal may be a heat-sink and probably is supposed to come in direct contact with the tops of the chips, to remove the heat that builds up. Apparently the shield's heatsink portion doesn't touch these chips, or at least not well enough.

Now, if I can find some sort of thermally conductive material that I can stick between the chips and the shield, it should sink the heat off of them nicely. Perhaps some square pieces of aluminum or steel, attached to the tops of the chips with thermal tape (usually used for CPU fan/heatsinks on computers). If I can figure out what the space thickness is under the shield, and match it with slightly thicker (1/32nd of an inch, perhaps) pieces of aluminum, it might just relieve the heat sufficiently to play for long periods of time.

There isn't enough room under the shield for any sort of fan on the chips, so this is about the only solution I can think of.

Another possible solution, which doesn't require disassembly of the unit, would be to construct a fan-box that mounts under the Dreamcast machine, essentially the game machine would sit on top of this fan-box. The fan box could draw air from several ports in the sides, perhaps one good sized port in the left, right and back sides (leaving the front closed for appearance), and blowing UP into the bottom of the game...

Anyone have any other ideas - 'cause this seems to be almost certainly what's wrong with my DC, and possibly a problem with other people's machines as well.

BTW: I disassembled my DC all the way down to the mainboard tonight, removing the shield and all, and reassembled it with no ill effects.