On the PC mainboard, there are a lot of mosfet lights used to regulate the supply of the CPU, chipset, and ram supply. When the mosfet is useless, it’ll lose the voltage of the circuit, even worse, making the mainboard not energy on, or set off the fan to rotate just a few occasions after which flip off.
Temporary introduction about mosfet
Mosfet is a area transistor that works on magnetic area impact to generate electrical present. They’re created from N-P-N semiconductors for reverse mosfets and P-N-P for ahead mosfets.
Mosfet ahead : After we put the black rod at D, the crimson rod at S, the analog clock X1 hugs many of the needle.
Reverse mosfet is used on PC mainboard: When inserting crimson rod in D, black rod in S, the clock will go up.
Mosfet consists of three poles:
Gate pole (Gate): pole G.
Base pole (Drain): pole D.
Energy pole (Supply): pole S.
Traits: Poles G and D are at all times insulated, poles G and S are at all times insulated. The measurement case between these poles is that the mosfet is shorted or detected. To find out the legs of the mosfet, you rotate the two mosfet legs in the direction of your physique. On the left is pin G, on the correct is pin S and above is pin D.
Methods to measure mosfet contains 2 methods: short-circuit measurement and examine the standard of mosfet mainboard lights
1. Quick-circuit measurement: When measuring short-circuit, we measure it immediately on the mainboard by adjusting the analog clock to the X1 ohm scale (or the diode scale for digital clocks).
The crimson rod is positioned at D, the black rod is positioned at S.
Invert the measuring rod, i.e. crimson rod at S, black rod at D.
+ If each instructions are measured: One clockwise is up a bit, and the opposite is as much as the tip of the dimensions => The sunshine is just not shorted on D – S.
+ Quite the opposite, when measuring in each instructions, as much as 0 ohms, the D-S lamp is brief.
2. Verify the standard of the Mosfet lamp: To measure the standard of the mosfet, you should utterly take away the mosfet and put it on a chunk of paper (insulation) to measure, or take away the G and S pins from the mainboard.
You measure 6-way measuring stick, only one clockwise up is nice mosfet lamp.
The black rod is positioned at D, the crimson rod is positioned at S.
Black rod in D, crimson rod in G.
Reverse the measuring rod for crimson rod at D, black rod at S => The meter solely goes up when positioned right here.
Pink stick in D, black stick in G.
Pink stick at G, black stick at S.
Pink stick in S, black stick in G.
The next circumstances are broken Mosfet lamps.
When measuring between G and S, there’s a low impedance near 0 ohms => The lamp is detected or shorted G – S.
Measured between G and D, there’s a low impedance => It’s a detected gentle or a brief G – D.
Constructive cost for G to activate the sunshine. Cost the constructive by leaving the crimson rod at S, the black rod at G. Then hold the crimson rod at S, put the black rod on the D leg. If the clock needle goes to 0 ohms, the sunshine is nice. If the sunshine doesn’t activate, the D – S leg is damaged.
Give G a tone to show off the sunshine. Load the unfavorable by leaving the black rod at D, the crimson rod at G. Then hold the black rod at D, put the crimson rod on the S pin. If the clock hand continues to be as much as 0 ohms, it’s a brief D – S, in any other case the clock is not going to go up. good.
Within the case of short-circuited measurement, or detected, you may exchange the equal mosfet. For instance, mosfet within the CPU supply circuit, then exchange the mosfet by getting from one other predominant CPU supply to interchange. There are additionally some mosfets like: LM1117, APL1085, FAN1084, L1117… is a voltage stabilizer ic that generates a voltage of 1.5v, 3v3 if not clear, you may examine the pinout with the datasheet
That is it, you’re employed laborious to comply with for some time after which bear in mind. As a result of my put up is simply too detailed, it appears a bit complicated. However truly the measurement may be very quick, it takes about 15 seconds to complete ah. Wishing you success.
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