AMETEK Ls Series - Manual (Page 105)

User Manual Lx / Ls Series
101
6.7 Non-Routine Amplifier Balance Adjustment
If an amplifier has been replaced on Lx/Ls models that have single-phase mode, it will be
necessary to check the amplifier current share balance and adjust if needed. For single box Ls-3
models, this adjustment is not required.
WARNING: This requires the top cover to be removed and should be done by qualified service
personnel only. Dangerous Voltages are present inside the AC power source.
To adjust amplifier balance, proceed as follows:
1. Remove all loads from the output.
2. Program the output to the 1-phase mode and 400 Hz.
3. Program the output voltage to 100 volts on the low voltage range with ALC off.
4. Check the amplifier gain balance by measuring the circulating current between
amplifiers. This current can be measured by monitoring the voltage at the test points
indicated in the table below on the current limit board. All test point measurements
are with respect to TP1 (common).
5. The voltage at each test point with no-load should be less than 20 millivolts. Make
any correction necessary by adjusting the Amplifier Gain on each amplifier. The gain
adjustment pot is indicated in the same table.
6. Check the balance at 50 Hz and again at the high frequency limit of the unit.
7. Contact California Instruments at [email protected] if the load balance exceeds
50 millivolts at the frequency extremes as the amplifier may be defective in this case.
Output
Phase
Current Limit Board
Test Point
Adjustment Pot R104 on
Amplifier assembly:
A or 1 TP2 Phase A (A1)
B or 2 TP3 Phase B (A2
C or 3 TP4 Phase C (A3)
Common = TP1
Table 6-5: Amplifier balance adjustments