Yamaha DX7 II FD Authorized Product Manual page 5

AC Power & Down Time:
Whenever the DX will not be used for an extended period of time, it is best to protect it
from potential disaster. Electrical storms and other natural or man-made disasters can give
rise to power surges, which may damage the digital circuitry of your DX — even if the
power is turned off. Either unplug your instrument when not in use, or invest in power
strips with surge protectors to safeguard all of your electronic equipment.
Service & Your Warranty:
The DX contains no user-serviceable parts. Opening it up or tampering with it in any way
will void the warranty, and may also lead you to experience some nasty electrical shocks.
If you have a problem with your instrument, please take it to ah authorized Yamaha
service center.
Modifications & Your Warranty:
Unless you are assured to the contrary in writing, you should assume that any
modifications made to your DX will void the original product warranty. Therefore, you
should make sure that you receive a warranty (or some other kind of guarantee) from the
person or company that is responsible for the modification.