#Mega Chip Woes
6 messages in this thread
I recently installed the Mega Chip 2000/500 on my A500, but I STILL have only
512K chip ram! I checked my work a dozen times and I still can't see what I am
doing wrong. A few times my machine wouldn't even boot, and when it does, I
still have only 512K Chip Ram.
A. Pagan
Angel,
To really figure out what might be the problem I need to know what
revision motherboard A500 you have. As a first guess I'd say that the
jumper changes necessary on JP2 were not done, or possibly that the trace
between the two lower jumper pads were not cut completly.
Another possible problem spot would be that instead of cutting the
trace near the trap door expansion connector you lifted a pin on the Gary
chip. (this assumes a rev 5 A500).
Let me know what revision machine you have and any other expansion
products you may have attached. We'll figure a solution for you.
Dean
DKB Software
Dean,
Thanks for the quick reply. I have a rev 5 motherboard. I Think I cut the
trace from the trap door okay, but the JP2 trace gave me a problem. At first
the machine wouldn't boot, so I looked over my work and went to work on the
jumper pads again. The end result was that the computer booted okay, but listed
less than 512K chip ram and 0K fast ram available. I have the following
expansion products on the motherboard: ECS Denise ICD's ADSpeed (I attatched
the clip frfom the megachip to Gary just in case). A501 Memory Expansion GVP
A500 HD w/ 2megs ram
A. Pagan
Angel,
Ok, it sounds as if the JP2 jumper is the culprit. Make sure the trace
between the lower and center pads is cut, and that there is a wire
connected between the center and upper pads. It's probable that you don't
have any connection there at all. Another thing to look for is any traces
that may have been cut while you were working.
Nothing you have installed in your machine should be causing any of the
troubles you describe. One thing that might be helpful is to find someone
to check over your work. They may spot something you have been
overlooking.
BTW, what is the number on the Agnus that you removed from your A500.
If it is the 8372A chip, try reinstalling it and see if you properly show
One meg of CHIP RAM. Let me know what happens.
Dean
DKB Software
Dean,
I looked over the diagrams in the manual and with a steady hand, made a deeper
cut between the lower and middle pads on the JP2 jumper. I soldered the other
two pads and held my breath as I booted up – VIOLA, 2Megs chip ram! I guess
that the original tracer cut I made wasn't enough. Thanks for your expert help
and a great product!
A. Pagan
Angel,
Glad I could be of help.
Dean
DKB Software