Yamaha PC4002M - Manual (Page 11)

INSTALLATION PRECAUTIONS
• If you are using long speaker cables, use the heavy
gauge cables which are practical, in order to prevent
damping factor deterioration and/or power loss
through the cable. The PC4002/4002M's speaker
terminals allow you to use even the heavy gauge
cables.
• The PC4002/4002M produces 430W + 430W (into
Sohms) in stereo mode, and 1400W (into Sohms)
in mono mode, so use a speaker system which has
sufficient capacity to handle this power comfortably.
You can protect speakers of lower rated input capacity
than the rated output power of the PC4002/4002M
by connecting a fuse directly between the speaker
and amplifier (see illustration). When using a system
such as the one illustrated, follow the procedure on
this page to determine the capacity of the fuse to
be used.
PO = |2 r
PO: Speaker continuous input power capacity (Noise
or RMS)
R: Nominal impedance of speaker
I: Required fuse capacity (A)
l = yP0/R
Example
Speaker continuous input power capacity
100W
Speaker impedance
Sohms
In this example
l=yi00/8
l==3.5A
IF THE CUPPING AND PROTECTION CIRCUIT OPERATION INDICATORS LIGHT UP
Indicator Cause Check
Protection Circuit Oper­
ation
Clip Indicator
Short in speaker termi­
nal, amplifier output ter­
minal, or cable
Examine the places
where shorting may have
occurred
The PC limiter is in op­
eration, protectiong the
power transistors
Amplifier overloaded
Make sure the speaker
system impedance is
more than 4ohms when
in stereo mode, and
Sohms when in mono
mode
The same as above
Protection indicator
Heatsink temperature
exceeds 100°C
Check the airflow and
take appropriate meas­
ures to keep the
amplifier(s) cool
The thermal protection is
in operation, protecting
the Power transistors.
A DC voltage of more
than Ì2V has occurred
at the output terminals
Contact your YAMAHA
distributor or service
center
The protection relay is in
operation, protecting the
speaker system