English Amiga Board - A600 2mb piggyback mod

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- - A600 2mb piggyback mod - help needed! (https://eab.abime.net/showthread.php?t=47402)

A600 2mb piggyback mod - help needed!

Hi Everyone

I've tried the mod & ran into a problem.
First the details:

A600 "JuneBug" Rev 1.5 board, unmodified, KS2.05 (37.300).
I got hold of 2 RAM chips from an old CL video card, they were socketed so no desoldering needed .
The chips are Hitachi HM514260CJ-6.

After soldering them (including the NC pins, only 28,29 were not soldered to the original RAMs) I mistakenly shorted the BCASU/BCASL wires.

The unit did boot up (KS screen showed up) but after about 3 seconds the screen went black & I noticed a burning smell :crying

After sorting out the short, I tried booting again. To my surprise, I got the KS screen, but I noticed the new RAM chips became insanely hot (could'nt touch them after only 3 seconds of operation!).
I immediately turned off the A600, to not risk further damage.

Is it safe to assume the new RAMs are fried? If not, what could make them run so incredibly hot in seconds?

I'm at a loss here, any advice on how to proceed will be greatly appreciated! :help

Thanks.

Quote:

Originally Posted by UberFreak (Post 594230)

Do you have a link for this mod ?, i never knew this existed, you've peaked my interest

thanks

perfect, i think i gonna give this a try :)

As to UF problem: yes, you fried the upper chips. Remove them and use other chips.

Remember to check for short-circuits between legs and with the floppy drive's left screw.

Thanks, will try to replace them.
The only other pair of RAMs I got here is AS4C256K16E0-60JC, which according to the datasheet are EDO chips.

Will these work or do I need only FPM ones?

It's a great mod if you have time and patience!

Here's where it all started..

http://eab.abime.net/showthread.php?t=34707

Ok, I've finally attempted the mod again, with another set of chips.
This time i checked & rechecked everything multiple times, and looks like it works now :)

I am getting some weird stuff with WHDLoad, like "illegal instruction" on Mad Elks's Technological Death demo, or freezes on other demos.
A few games I've tried seem to work fine though.

Is there a program I can use to stress-test chipmem? I want to make sure the problems I'm seeing are not memory related (since the RAM I used is EDO, and mixing FPM & EDO is known to cause problems on occasion).

Thanks!