Yamaha DX7 4X EXPansion Installation
1: Introduction
The DX7-4X-EXP a powerful option board that provides increased memory and greater control of
the DX7.
THIS INSTALLATION WILL REQUIRE SOLDERING EXPERTISE AND ELECTRONIC
KNOWLEDGE. THE INSTALLATION SHOULD BE REFERRED TO A QUALIFIED
TECHNICIAN.
The soldering work entails direct wire connection to IC's already installed on a PCB. The
backup battery voltage is still live. This is a volatile Lithium battery. We accept no
responsibility for the work you perform on your DX7, your safety or material losses.
Precautions!
High Voltage Safety Warning
Unplug the audio cable. Turn the DX7 power switch OFF and disconnect the AC power cable
before opening the DX7.
ESD Precautions and Proper Handling Procedures
You should observe standard static-safe handling behavior when working with sensitive electronic
equipment such as synthesizers:
o Avoid carpets in cool, dry areas.
o Dissipate static electricity before handling any system components by touching a
grounded metal object.
o If possible, use anti-static devices, such as wrist straps and floor mats.
o Take care when installing the board. A damaged pin can render the board unusable.
o Prevent damage to the connectors by aligning connector pins before you apply pressure.
A damaged pin can render the board unusable and can cause damage to system
components at power-on.
o If disconnecting a cable, always pull on the cable connector, not on the cable itself.
Tools Required
o Standard Philips screwdriver.
o Standard flat-head screwdriver (small).
o Standard soldering iron and solder. Because most soldering irons are grounded-tip, you
must unplug all cables from the DX7.
DX7-4X-EXP Page 1 of 6 Install v2.11
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Condition of DX7
While the DX7-4X-EXP will replace the functionality of damaged or missing EPROM and/or
SRAM chips, it will not correct other problems your vintage synthesizer may have. It is
recommended that the synth be in otherwise good condition before beginning the installation. For
instance, the battery voltage should be checked and the battery replaced/repaired by a tech if
necessary. Sockets for the EPROM and SRAM chips should be in good working order and not be
dirty, oxidized, rusted or otherwise compromised. If repair is required, do it before installing DX74X-EXP.
2: Installation
Open the DX7
Using a Philips head screwdriver, remove the 5 screws from the front panel. Two are located
on the left front. Two are located on the right front. A final one is located on the right rear. Set the
screws aside, noting that the rear panel one is the shortest.
Back up your patches if they are important to you!
(Re)Move the Keybed & Remove the Keyboard Rail
Some of the solder connections are very close to the silver colored metal keyboard rail. By
moving the keybed (the chassis with the keys) and removing the silver keyboard rail, you will
have better sight lines and freedom of movement when installing the DX7-4X-EXP board.
Remove the 4 large external screws from the underside of the keyboard along the front
edge. The photo below shows the inside front edge of the empty case bottom and illustrates the
location of the 4 screws. You will, of course, be unscrewing from the DX7 underside.
DX7-4X-EXP Page 2 of 6 Install v2.11
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