Troubleshooting - Roland CPM-300 Owner's Manual

Troubleshooting

There is no sound.
Has the power cord been pulled out of the socket, or is it not seated well? Also check for any shorts in the power
cord resulting from a cut or broken cord or from damage to the cord covering.
Are the channel faders or the MASTER fader lowered? Also check to make sure the channel SENS knobs are not
rotated too far counterclockwise.
Connecting a cable to AMP IN jacks cuts off the signal from the mixer section. When an equalizer or other device
is connected, confirm that the MIXER OUT and AMP IN jacks are both securely connected. Check to see if the vol-
ume of any device connected between MIXER OUT and AMP IN is turned down. (
Is a device with a HOT pin 3 connected to Channel 1? Pin 3 on the CPM-300's Channel 1 is wired to ground. No
sound will be produced if pin 3 of the connected device is HOT.
The pin assignment for the CPM-300's Channel 1 is shown in the diagram below. Check the pin assignments used
by other devices before connecting them.
XLR Type (Unbalanced Input)
TRS Standard Phone Type (Unbalanced Input)
If the speaker cable's "+ and -" wires are shorted, or if speakers rated at less than 4 ohms impedance are connected,
the PC Limiter Circuit is activated in order to protect the speakers, and the sound may be cut off or distorted. Check
to make sure the speaker cables are not shorted and that the speaker impedance is not less than 4 ohms.
→
(PC Limiter Circuit
The Thermal Protection Circuit cuts off the sound if the internal power amp overheats.
Stop operation of the equipment for a while to allow the heat to dissipate sufficiently. Although the unit automati-
cally restarts when the power amp's interior temperature falls, if the Thermal Protection Circuit is activated again,
check to make sure that the operating environment and connected speakers conform to the CPM-300's specifica-
tions. Minimum recommended load impedance for the CPM-300's power amp is 4 ohms. (Thermal Protection
→
Circuit p. 17)
When DC (direct current) is generated in the output sent to the speakers, the DC Detection Circuit cuts off the
sound to protect the speakers. The CPM-300 restarts a few seconds after generation of direct current in the output
ceases. (DC Detection Circuit
The internal reverb is not working.
Make sure that the SEND knobs for the channels and the master section to which you want effects applied are not
turned counterclockwise.
Make sure that the DIGITAL REVERB LEVEL knob is not turned counterclockwise.
Make sure that the faders on the channels to which you want effects applied are not lowered.
18
GND(SLEEVE)
HOT(TIP)
p. 9)
→
p. 17)
3
1 2
1:GND
2:HOT
3:GND
GND(SLEEVE)
GND(RING)
→
p. 11)
HOT(TIP)