Path Checking – Diode Value Method
The diode value method is used to detect short circuits, open paths, and faulty components on smartphone motherboards using a digital multimeter in diode mode.
1. Testing Procedure
- Set Range: Select the Diode Value mode on the multimeter.
- Probe Placement: Place the red probe (+) on Ground (GND).
- Check Path: Place the black probe (-) on the checking point such as a connector pin or component terminal.
- Compare Reading: Compare the measured value with the known diode value for that circuit path.
2. Multimeter Reading Interpretation
| Reading | Path Status |
|---|---|
| 0.000 | Path is shorted with ground |
| OL | Path is open |
| Original value (or near) | Path is normal |
3. Troubleshooting Short Circuit Paths
If the reading shows 0.000, the path is shorted with ground.
- • Check parallel capacitors on that path
- • Replace shorted components if found
- • Check the controlling IC for internal short
- • Rehot, reball, or replace faulty IC
4. Troubleshooting Open Paths
If the multimeter shows OL, the circuit path is open.
- • Check series components on the path
- • Replace open resistors or coils
- • Trace broken PCB tracks
- • Use jumper wire if internal path is broken
Technician Tip
Always compare diode values with a working board or schematic if available. Slight variations may occur, but large differences usually indicate component failure.