are you going to start making kit/daughterboards for the
mp1 so we can buy them and install
ourselves?
Thanks
George
Sent: Saturday, November 09, 2013 7:40 PM
Subject: Yamaha FX500 Batteryless Mod!
I have a Yamaha FX500 effects processor which I bought new in 1989.
The original backup battery has been holding out all these years to this day,
believe it or not.
Pending the succesful batteryless mod I did a few weeks ago on my ADA MP-1, I
decided to do the same to the FX-500.
The FX-500 drives its 8x8K SRAM chip a little differently from the way it's
done in the MP-1. This mod requires that one of the signals be inverted and sent
into a different pin, requiring a more complicated circuit. Whereas I built the
chip daughterboard for the ADA MP-1 using generic stripboard, for this more
complicated job I decided to make a custom PCB in order to keep it compact.
Also, before doing anything, I had to desolder the original SRAM, which
Yamaha mounted straight to the circuit board, and put in a 28 pin socket. This
socket lets us insert our daughterboard and go back to the SRAM chip easily if
that doesn't work. We don't want to be soldering our work to the circuit board;
not to mention that the header pins would require us to drill out to 35 mils,
which would destroy the plated through holes.
It works great. The battery is gone, and the FX-500 is retaining
everything.
Pics:
| Etched, Drilled Board: |
Toner Resist Removed: |
 
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