PS23003AU dual power supply

Schematic and repair instructions

PS23003AU dual power supply

PS23003AU dual power supply schematic diagram (one half)

Symptom: current limit stops at 1.5 A (current limit knob has no effect until it's turned half way)

Cause:IC N2 (LM741) is damaged.

Repair:

1. Open the case
2. Discharge the big capacitor by placing a low value, power resistor between the anode of diode U8 and the cathode of diode U6
3. Replace the IC (this is the lower of the 2 8-pin ICs)
4. Modification that may prevent it from happening again: add a 100 nF capacitor across pins 3 and 4 of that IC
5. Modification that will discharge the big capacitor when the power is off: add a 10 kΩ resistor across the the anode of diode U8 and the cathode of diode U6