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TROUBLESHOOTING TIPS
1. General Troubleshooting Procedures
1.1 These units are very flexible in regard to setup and operation, which means that it will be
much easier for the customer to install and/or setup the unit incorrectly. Be sure to check that
the product was installed properly, and that all switches are in the correct positions for that
particular usage. Refer to the AmPlus™ 50 and 100 Installation diagrams and the Amplifier
Controls pages for more information.
1.2 The main circuit board is built with the surface-mounted IC's mounted on the underside of
the board. There are several test-points located on the top of the PCB which are easier to
access than the devices themselves, which can be used to troubleshoot down to a smaller
area before probing on the bottom of the board is necessary. Refer to the appropriate
schematic diagram, and look for the diamond shape near the signal paths. These points
are silk-screened on the top of the PCB and labelled as TS2, TS3, etc. Refer to the PCB layout
diagrams for more information.
1.3 If you need to operate the unit with the PCB in the upright position, you must connect a
ground wire from the unit chassis to one of the ground points on the PCB for proper operation.
2. Hum and noise problems
2.1 If the customer is experiencing hum and/or noise problems, check to make sure the
following installation guidelines were met.
• Connect high impedance units, such as tape players and CD players, to the amplifier
with shielded, single conductor cable. Keep cable lengths less than
10 feet (3 meters).
• Use twisted shielded pairs on microphone inputs.
• Keep input cables away from:
-Loudspeaker cables to prevent inductive feedback.
-Power lines or transformers.
• For output loudspeaker connections, Class II wiring is suggested. Use standard
#16 AWG wire. Keep loudspeaker cables away from power cables.
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