Tech Tip - Infinity MODULUS Service Manual

Modulus
We strongly suggest a voltage is checked before a Modulus amplifier replacement takes place. It deals with the
output voltage coming from the toroidal transformer (power supply).
manufactured with the power supply miswired, resulting in a higher than normal supply voltage. The
supply is mounted and located on the inside of the base where the switch/controls are. After removal from the
subwoofer cabinet, notice there are two cables coming from the power supply. The one to check is the larger,
three wire cable. With both cables unplugged from the amplifier, of course, plug the power supply in and turn it
on. Check the blue-blue wire voltage terminated at the end of the molex connector with a multimeter set on AC.
It should be 76 - 80 volts AC. If it is 90 - 95 volts the supply is miswired — and if the subwoofer is
reassembled in this condition the amplifier assembly is probably going to fail some time in the future.
If the voltage is correct, read no further . But if the voltage is high here are the instructions for the rework:
1. After removal, turn the power supply/base towards you so you are facing the inside (and the plastic
cover covering the connections). You should be facing the base so the wires are exiting the cover
on the right side.
2. Remove the four 11/32" nuts attaching the plastic cover to the base.
3. On the right side of the plastic cover there should be some adhesive where the wires are exiting the
cover. With a box cutter, knife or similar tool make a cut around the perimeter of the cover (where
the glue is) so it can be pried up. NOTE: Not all the glue has to be pried up or cut off,
particularly in the area of the wires. Too much enthusiasm will result in a cut wire - USE
CAUTION.
4. Pry the plastic cover up and away from the base board. The right side may still be attached with glue.
All internal connections should now be exposed.
5. The two connections which must be "swapped" are the ones the pink and violet wires are
attached to. Unplug these wires and replace in each other's location.
6. Replace the plastic cover and bolt down with the four nuts.
7. The cover must be re-glued with hot glue, silicon seal or similar adhesive to form an airtight seal
at the cover on the wire side. Failure to do so may result in an air leak, adversely affecting the
subwoofer's future performance.
8. Power up and check previous wires (at the molex connector) for 76 - 80 VAC.

TECH TIP

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A small number of units were