Yamaha DX7 II-D User Manual

Upgrade your Yamaha DX7 II-D to Yamaha DX7 II-FD

February 2009 By CloudsWalker www.cloudswalker.com

Missing Parts on the Yamaha DX7 II-D :

IC5 Integrated Circuit 16 pin DIL : TC40H174P
6 x D-Flip-flop, can be replaced by 74HC174

IC6 Integrated Circuit 14 pin DIL : 7405 (TTL)

IC22 Integrated Circuit 28 Pin DIL : HM65256BLP12
SRAM, can be replaced by HM62256LP12 or equivalent

IC23 EPROM 27512 or 27C512 for the new Operating System

IC24 Integrated Circuit 28 Pin DIL : WD1772-PH (1986)
Western Digital Floppy Disk Controller

!!! 3,5 inch Floppy Disk with Drive Select 0 !!!

CN1 34 pin Floppy Disk Male Connector

34 pin flat cable between Main Board and Floppy Disk

Power cable between Power Supply Board and Floppy Disk

Parts collecting :

74HC174 is easy to found and found also one IC socket 16 pin DIL

7405 is easy to found and found also one IC socket 14 pin DIL

HM62256LP12 or equivalent is relatively easy to found and found also one IC socket 28 pin

EPROM 27C512 is relatively easy to found and found also one IC socket 28 pin DIL

WD1772 can by found on the Web … or removed from one Atari ST !!! + IC socket 28 pin

The floppy Disk can be 1.44Mb/720kb new … BUT with Drive Select 0

Battery replacement :

It will be judicious at this Time to change your Backup Battery ( 3V CR2032 )

It’s better to solder a socket. This socket can be removed from an old PC Mother Board

Procedure :

I’ve open my Yamaha DX7 II-FD and we can see a soldered Battery

I’ve remove the EPROM with Operating System

I’ve program one new EPROM 27C512 with my Personal Computer

I’ve remove the soldered ROM in my Yamaha DX7 II-D and remove solder in holes for IC5,
IC6, IC22, IC24 and CN1, we can also see a soldered Battery