Lambda EMS 7.5-75 Operator's Manual

Contents

Lambda EMS 7.5-75 Operator's Manual Manual pdf 38 page image

proceeding to the next step. The digital meter doesn’t have a zero adjustment and the fullscale is on the back of the meter, or on the A100 PCB R406 or R402.5.3.2 VOLTAGE CHANNEL AND VOLTMETER CALIBRATION1. Disconnect any load from output of the power supply.2. Connect a digital voltmeter across output terminals.3. Turn the Voltage control completely counterclockwise and Current control clockwise.4. Apply input power and turn the circuit breaker on.5. While monitoring the voltmeter that is across the output terminals, adjust R55 until thepower supply output voltage starts to increase in the normal polarity. Adjust R55 in theopposite direction until the output voltage decreases to zero. Do not continue adjustmentpast this point.6. Rotate Voltage control fully clockwise. While monitoring the voltmeter that is across theoutput terminals, adjust R3 until voltage across output terminals is equal to themaximum rated output voltage of the power supply.7. The front panel voltmeter should agree within 2%. If it does not, adjust thepotentiometer that is located on the front panel voltmeter (adjust R406 on A100 bd. ifunit is a 600w/ 1KW) and check its zero adjustment if voltmeter is analog, (digital meterhas no Zero Adjustment).8. Turn circuit breaker off.5.3.3 Current Channel and Ammeter Calibration9. Connect a short across the output terminals of the power supply.10. Connect a millivoltmeter across the current shunt sense terminals observing correctpolarity.11. Turn the Voltage control clockwise and the Current control completelycounterclockwise.12. Turn the circuit breaker on.13. Adjust R47 (or R77 if unit is a 5KW ) until the voltage across shunt starts to increase.Adjust R47 (or R77) in the opposite direction until the voltage across shunt decreases tozero. Do not continue adjustment past this point.14. Turn Current control completely clockwise. Adjust R5 until voltage across senseterminals of the shunt is equal to the rated voltage of the shunt which in most cases is100 mV. Some power supplies (usually high current units) are equipped with a 50 mVshunt.15. The front panel Ammeter should read the maximum output current of the power supply.If not, adjust the potentiometer that is located on the front panel ammeter. If the unit isa 600W/1KW adjust R402 which is located on the A100 Bd, the digital meter has noZero Adjustment.16. Turn circuit breaker off.17. Disconnect the AC input power.83-473-000 Revision J5 - 2 Calibration and Troubleshooting

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