C37
P3
P4
14
J14
P5
P6
2 1
RP2
J15
J16
RP1
J1
U5
U4
ADD THIS JUMPER FOR
0.775V INPUT
SENSITIVITY IN CH2
ADD THIS JUMPER FOR
0.775V INPUT
SENSITIVITY IN CH2
BACK OF AMPLIFIER
19
18
Figure 9
In Case of Difficulty
If you’re having trouble or suspect a problem with the pm125/ pm420, try some simple troubleshooting before
contacting an Authorized Carver Professional Service Center.
No Sound, No Power
This is usually an indication of a power supply problem, either the power line itself or the amplifier’s power supply.
1.pm125 / pm420 power is switched off.
2.Linecord is disconnected.
3.Poor fit between the plug and AC receptacle.
4.Power off at AC receptacle (check with tester or lamp).
5.The amplifier is plugged into a switched outlet. Verify that the outlet is live.
6.The pm125 / pm420’s circuit breaker has tripped. Reset the Breaker.
Power On, Low Output or No Output
Low or no output problems are usually signal-source, bad cable or partial output short circuit related. If the items listed
below check out, then the problem may be internal to the pm125
/
pm420.
1.The Input Level controls are set too low.
2. Move the input connections to another amplifier that you know is working to verify that it is not a source problem.
3. Check the speaker connections. Be sure that there are no small strands of wire touching similar strands coming from
the other wire in the cable.
4.Make sure the speakers are functioning correctly.
5.If you are using bridged-mono mode, ensure that the Stereo / Mono switch is set correctly.
6.Use a voltmeter to determine if the power line voltage is dropping excessively when the amplifier is driven hard.
Playback Is Mixed with Hum
1.Check or replace the connecting cables.
2.Make sure that each screw terminal connection is tight.
3. Signal cables may have been routed too closely to AC cables, power transformers, motors or other EMI
inducing device.
4. Try connecting another source to the power amplifier inputs. If the hum stops, the problem lies with the
original source component.
Distortion
Distortion is usually caused by excessive loss in the input controls (the mixer/ equalizer / crossover can’t produce
enough output), overdriving resulting in output clipping, or current limiting caused by excessively low load
impedances.
