Non-Routine Calibration - Ametek California Instruments MX15 Series User Manual

6.5 Non-Routine Calibration

The non-routine calibration may involve removing the front, rear, or top cover of the power
source. Use extreme caution when performing any of these tasks while the system is connected
to AC mains and/or powered up.
6.5.1 Power Source Gain Adjustment
For any MX configuration that requires two or more amplifiers to be operated in parallel for
increased current output, the amplifier gains have to be matched as closely as possible to
ensure equal current sharing. If an unbalance exists between amplifier outputs, one or the other
amplifier will deliver more current and may run into its current limit protection before full output
power can be attained.
This procedure details the gain adjustment. Generally, MX units are shipped with the gains
already set correctly so this task should only be undertaken if an amplifier has been replaced or
if two MX units are to be combined that were not originally shipped from the factory as such. In
the case of the MX15, this will only be necessary if a second or third MX15 is purchased and will
be added in parallel to another MX15.
To make this adjustment the front cover must first be removed in order to get access to the
power module output terminals. Proceed as follows:
1. Shut off all power to the cabinets. Disconnect the two wires going to Terminal 6 and
Terminal 7 on the right front of the power module. Do this to the module(s) in the auxiliary
cabinet(s) only. Place some temporary insulation over the lug ends.
2. Connect a DMM between terminals 6 and 7 on the module in the master cabinet. Power up
the cabinet. Set the controller to the 300V range, program 230V at 60Hz. Enable the output
by pressing the OUTPUT ON/OFF key. Measure the module output voltage and write it
down. Press the OUTPUT ON/OFF key to disable the output.
3. Move the DMM leads to the module terminals 6 and 7 in the auxiliary cabinet. Press the
OUTPUT ON/OFF key again to enable the output. Verify the module output is within
50mVolts of the module in the master cabinet. If it is not, adjust the pot behind the hole in
the lower left corner of the module so the output matches the master output within 50mVolts.
Press the OUTPUT ON/OFF key to disable the output.
4. If power system under adjustment is an MX45/3, then repeat step 3 above for the second
auxiliary cabinet.
5. Power down system and replace the wires to terminals 6 and 7 on the auxiliary power
module(s).
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