Switching Power Supply Service Manual
- 7. REPAIR SERVICE
- If a power supply fails to operate, perform the following steps prior to sending in for repair.
- a. Check all connections. There may be a short circuit in the output side of the power supply.
- b. Check the output voltage variable resistor (VR) adjustment screw. If the output voltage is set too high the power supply will sense an over voltage and shut down the output.
- c. Check the AC input voltage. If it is out of the power supply's input voltage range, the power supply will not operate. Some power supplies are equipped with an input voltage selection switch (110 volt / 220 volt). If the selection switch is set on 220 volts and the input voltage is 110 volts, the power supply will fail to operate.
- IMPORTANT NOTE
- Applying an input voltage of 220 volts with the selection switch set on 110 volts will destroy the unit.
- d. Remove the output load and cycle the input power (with a 10 second gap between the off and on state). Check the output terminals to see if the correct voltage is present. If the correct voltage is present, measure the current required by the load. The load current may be overloaded. If no output voltage is present, turn off the input voltage and allow the power supply to cool. Once the unit has coaled, apply input power. If the power supply operates, the shut down was a result of an over temperature condition.
- If the power supply still does not operate, perform the following steps.
- e. Tighten all of the power supply terminal screws before shipping.
- f. Ship only the power supply. Do NOT ship any accessories (such as the AC input cord or the manual).
- g. Send a brief description of why the unit might have failed.
- h. Pack the power supply in a sturdy carton with adequate padding around the unit. This will prevent damage during transportation.
- i. Repairs will take up to 7 working days (not including the shipping time).
- IMPORTANT NOTE
- All information is based on the WENZHOU MINGWEI Switching Power Supply User Manual - Version 1 and is provided in good faith, but without any warranty or guarantee as to fitness to purpose. It is solely left to the discretion of the user as to the suitability of the information for their application.
