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You have now determined that the power supply is running and that there are DC supplies being generated. You should now
check the power supply using a mains supply input.
1. Remove all the connections used for the DC bench supply test. Be sure to remove the switch on the opto isolator -- if it's
left in position and switched on, the power supply will not power up.
2. At this stage you WILL NEED a MAINS isolation transformer. Note: This is not the same as
3. Plug the mains isolation transformer into the mains AC supply.
4. From the output of this transformer, connect the AC power cord to the amplifier.
WARNING: Using a Variac or noise isolation transformer instead of a MAINS isolation transformer could lead to
injury or death.
5. The unit should go through its normal start-up procedure. Once it has stopped flashing, move the Operate switch to the ON
position. The amplifier's power supply should start up after approximately 2 seconds.
6. If the protection light flashes, disconnect the AC power cord and check the chassis fuse and replace if necessary.
7. Also check the soft-start resistors (the flat thick-film 20-ohm resistors alongside the main transformer). If the resistors are
open circuit, use a temporary resistor during this phase, as changing the soft-start resistors is difficult and the resistors are
fragile. See Diagram 4 for details of the temporary resistor.
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