Proper use of a power supply tester prevents equipment damage and personal injury. Follow these steps and avoid common pitfalls.
Essential Pre-Testing Preparation
Ensure the power supply is unplugged. Verify the tester is compatible with the PSU's form factor (ATX, ATX12V, EPS). Identify all PSU connectors and their designated ports on the tester.
Step-by-Step Testing Procedure
Connect the 20/24-pin motherboard connector firmly to the tester's main socket. Attach the 4/8-pin CPU connector to its dedicated port. Connect peripheral cables (SATA, Molex, PCIe) if testing their rails.
Important: Plug the PSU into a grounded AC outlet only after all connectors are secured to the tester. Toggle the PSU's own power switch (often labeled 'I-0') to the ON position.
Observe the LED displays or digital readout for each voltage rail (+3.3V, +5V, +12V, -12V, +5VSB). Compare readings against the ATX specification tolerances (typically ±5% for critical rails).
If equipped, press any load buttons for the +5VSB (standby) rail to verify stability.
Critical Mistakes to Avoid
- Ignoring the PSU's Physical Switch: Failing to turn on the PSU's rocker switch is the top cause of false negatives.
- Incomplete Connection: Partially seated connectors lead to inaccurate or missing voltage readings. Ensure audible clicks.
- Mishandling Load Function: Only activate +5VSB load testing after initial voltages are stable. Misusing load buttons on other rails is unnecessary and potentially harmful.
- Misinterpreting 3.3V Rail: Some testers measure this via the 24-pin connector; attempting to test it via Molex/SATA will fail.
- Neglecting Grounding: Touching exposed pins on the PSU connectors or tester while powered risks shock. Always handle by insulated edges.
- Assuming No-Load is Valid: Testers provide minimal load. A passing result indicates voltage presence within tolerance under no-load conditions, not full load stability.
- Skipping Pin Inspection: Physically check connectors for bent, missing, or corroded pins before connecting to the tester.
- Forgetting Capacitor Discharge: Wait at least 2 minutes after unplugging before handling PSU internals. Residual capacitor charge can be dangerous.
Post-Testing Protocol
Turn off the PSU rocker switch. Unplug the AC power cord from the outlet first. Only then disconnect all PSU cables from the tester. Document readings for future reference.
