Sigkill and freezing after memory upgrade

We just did the memory upgrade on a MK2A and it now freezes after a few button presses. Attempting access to Hijack yields a "Sigkill" error message. There does not appear to be a short anywhere in the soldering and the terminal reports all extra memory as passing. The weird thing is it reports 48 MB rather than 32MB. Disconnecting the RAS line from the extra memory restores the player to regular operation. Any ideas?

Thanks,
Stu

Is there any way to really test the memory? bad chip maybe? I had a memory stick in my pc once that registered the wrong size and caused all kinds of problems. just an idea.

Was thinking maybe a bad chip too. Thanks!

Stu

Well the fact it's reporting as 48MB instead of the real 32MB will be the reason it's crashing. What's possibly happening is that the memory is "ghosting" and appearing twice.

This could be for two reasons I can think of:
1) The new memory is being addressed twice. Standard sequential memory tests mightn't pick this up.
2) Somehow capacitance is causing phantom memory.

Mark's very basic memory check should pick up either but it's possible it's not.

I doubt a memory chip since for it to pass the memory test, all four chips would have to behave the same.

Is it possible there is a short on the CPU between the two RAS pins? That would make the new 16MB appear at both locations eventhough it's the same physical memory. It would also pass the memory test I think too. I'm not sure if Mark is writing memory addresses into locations to check for this sort of thing.

After writing all this, I'm tipping a short on the RAS pins at the CPU.

Quote:

Is it possible there is a short on the CPU between the two RAS pins? That would make the new 16MB appear at both locations eventhough it's the same physical memory. It would also pass the memory test I think too. I'm not sure if Mark is writing memory addresses into locations to check for this sort of thing.

After writing all this, I'm tipping a short on the RAS pins at the CPU.

I second this opinion. All the symptoms are correct...