4
PA640 PANEL DESCRIPTIONS
P O W E R
M A N U A L O N
+ – – +
C H 2 C H 1
PROTECTION
S P E A K E R S
+ – – +
C H 6 C H 5
PROTECTION
+ – – +
C H 4 C H 3
PROTECTION
SPEAKER IMPEDANCE
STEREO MODE: 8 Ohms Min.
BRIDGED MODE: 16 Ohms Min.
M A N U A L O F F
( R E M O T E O N / O F F )
S P E A K E R S
S P E A K E R S
+ –
B R I D G E D
+ –
B R I D G E D
+ –
B R I D G E D
6
7
8
9
10
6
7
6
7
1 2 0 VA C
6 0 H Z
F U S E
5 A
Fig. 3 PA640 Output & AC Panel – Features and Functions
6. PROTECTION Indicator LED's. These red LED's, one for each pair of channels, light for 3 to 4 seconds
when the amplifier senses a short circuit or a very low load impedance (under 2-Ohms) at the speaker
terminals. This protects the amplifier from potentially harmful conditions. If the short condition or the
input signal is not removed, the amplifier will continue to cycle on and off at the 3 to 4 second interval.
CAUTION: Do not allow this to continue for a lengthy period of time. Reduce the volume, remove the
short or low impedance condition and try again.
NOTE: The PROTECTION LED's will also light for 5 to 8 seconds when the amplifier is first turned
on. This is a normal muting function that quiets the amplifier during start-up.
7. SPEAKER Terminals. These plug-in 4-terminal screw connectors permit speaker wire sizes up to 12
gauge. When making connections for the STEREO mode, be sure to observe the "+" and "–" polarity
markings, just under the CH1, CH2, etc., markings, for each wire pair going to the speakers.
CAUTION: When making connections for the BRIDGED mode, remember only one speaker is being
attached per amplifier pair. Be sure to observe the outer "+" and "–" polarity markings on the 4-terminal
connector, as shown on the panel, for the one wire pair connecting to the speaker.
8. POWER Switch. When pressed to the IN position, power is applied to the PA640. This is the MANUAL
ON position. When pressed again, it releases to the OUT position (MANUAL OFF), turning the unit
OFF.
In addition, this switch must be left in the MANUAL OFF (REMOTE ON/OFF) position to permit external
DC Voltage control of power ON/OFF for the PA640.
NOTE: The PA640 may also be powered ON/OFF with an external AC line switch (such as the
switched AC outlet of a preamp, timer, etc.). For this type of operation, leave the POWER switch
depressed to the MANUAL ON position.
9. AC LINE Cord. Depending on the application, plug into a switched or un-switched 120V 60 Hz AC
outlet.
10. FUSE. When required, replace only with a fuse of the same type and rating (5 A 220V AC).
Replacement with a fuse of higher rating will not protect the amplifier and will void the warranty.
PA640
