DC Power supply Troubleshooting

Issue: Korad DC Power Supply Output Shorted, Showing Full Current

• Symptoms: The power supply was showing maximum current output even with no load connected. This is a typical indication of a short circuit or fault in the output section.

• Diagnosis:

  • Checked output filter capacitors: All were in good condition (no bulging, leakage, or low ESR).

  • Checked output diode: Found the N5408 (MIC) diode was continous from both side

• Solution:

  • Replaced the faulty N5408 diode with a new one.

  • After replacement, the DC power supply started working normally. The current reading returned to normal levels, and output voltage was restored.

The N5408 is a general-purpose high-current rectifier diode (commonly used in the output section for rectification and protection). If it fails open, it can interrupt the flow of current to the output or confuse the regulation feedback loop, causing erratic behavior like constant max current display.