procedures
Electronics Diagnostics
🔌 Electronics Diagnostics - Multimeter Testing
Resistors (Ω) and Variable Resistors
| Component Type | Multimeter Mode | Test/Diagnosis |
|---|---|---|
| Resistors | Resistance Mode (Ω) | A closed resistor tests as a dead short (no resistance). If a resistor is open, you will get no resistance. Resistors can act like a fuse. Check and test if the devices are in series or parallel. |
| Variable Resistors | Resistance Mode (Ω) | Sweep to measure resistance, or match to set rating (Potentiometers, etc.). |
Inductors (Coils) and Fuses
| Component Type | Multimeter Mode | Test/Diagnosis | |||
|---|---|---|---|---|---|
| Coils (Inductor) | Continuity Mode ( | ) | Must have Continuity to be good. No Continuity means the Coil is BAD. (2 Terminals = +/-) | ||
| Fuses | Continuity Mode ( | ) | Must beep (indicating continuity) to show the fuse is not blown. No continuity means the fuse is BAD. Fuses can be a Resistor or even a Diode. |
Diodes, Mosfets, and Transistors
| Component Type | Multimeter Mode | Test/Diagnosis |
|---|---|---|
| Diodes (→←) | Diode Mode (→←) | Place positive on the “dark” side and ground on the “white” side to test. Measures voltage drop. |
| Bridge Rectifier | Diode Mode (→←) | Test pins A and D against B and C (four specific combinations provided in the original document). Reverse polarity on all combinations should be 0. Can act like a fuse. |
| Mosfets (Gate, Drain, Source) | Diode Mode (→←) | Any continuity between Drain and Source means the Mosfet is bad. N-Type (NPN): Charge the gate with (+) to turn OFF (OL). |
| Transistors (made up of Diodes) | Diode Mode (→←) | Test Base to Collector/Emitter (and vice versa) for both NPN and PNP types. Any continuity means the Transistor is bad. |
Mosfet Pinouts
| Type | Pinout |
|---|---|
| 8-Pin | 4 Drain, 3 Source, 1 Gate |
| 6-Pin | 4 Drain, 1 Source, 1 Gate |
| 4-Pin | 1 Base (Gate), 2 Collector (Source), 1 Emitter (Drain) |
| General | PIN 1 (Drain) always has a marker, such as a dot. |
Capacitors (→←) and Switches
| Component Type | Multimeter Mode | Test/Diagnosis | |||
|---|---|---|---|---|---|
| Capacitors (→←) | Diode Mode (→←) / ESR | Better/Best: Use an ESR Meter. Match readings to the listed rating. Short the +/- to discharge as needed. | |||
| Capacitors (Resistance) | Resistance Mode (Ω) | If a cap’s resistance reading is more than 10% difference, replace it. | |||
| Capacitors (Continuity) | Continuity Mode ( | ) | If a capacitor has ZERO/0 continuity, it is bad/shorted. Capacitors for/under Chips (GPU, CPU etc.) will have a very LOW resistance and will have continuity. | ||
| Switches | Continuity Mode ( | ) (Beep) | Should beep only when turned on. |
Integrated Circuits (IC)
General IC Testing:
- Charge Integrated Circuit (PWM IC): If any of its capacitors test as shorted, the IC is shorted and needs to be replaced.
- Super IO: This is basically a big power management IC. Check capacitors around a Super IO; any shorts means the IC is bad.
- A Circuit Diagram is generally needed for in-depth testing of complex ICs (Clock Generator, Audio, RJ45, Super IO).
- The Crystal Oscillator is needed and needs to be functional for the Clock Generator IC.