Controlling 12/24V DC motor - mosfet circuit

[LarryD]

@hk_jh

both are 0V (Gate to GND2 and Drain to GND2)

When Vgs is 0V, Vds should be 12V.

If Vgs is 0 (zero) volts and Vds is 0 volts this suggests a wiring error, a mechanical solenoid problem, a MOSFET problem.

[LarryD]

BTW

Make sure your meter is properly set to measure DC voltage by measuring the 12V supply.

[hk_jh]

@LarryD

BTW

Make sure your meter is properly set to measure DC voltage by measuring the 12V supply.

It is.

@LarryD

When Vgs is 0V, Vds should be 12V.

This is not happening with solenoid 1 and 5.

It is happening with all the rest of the solenoids.

[hk_jh]

@LarryD

If Vgs is 0 (zero) volts and Vds is 0 volts this suggests a wiring error, a mechanical solenoid problem, a MOSFET problem.

I've check with different solenoids and the problem is still happening so the solenoid is not the problem. Wiring seems to be just fine. Is there any way I could check the MOSFET without take it out?

[hk_jh]

I might have found it(?!) The resistor between the Gate and the Source of solenoid 1 is showing only 18R resistance while it should show 6k8 resistance?

edit: and solenoid 5 show 1k3 resistance between Gate a and Source while all other show ~6k8 resistance

edit: the resistor code are all the same meaning it is a 6k8 resistor from it color code

[LarryD]

18R

Edit

Triple check all resistor values with a meter.

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Confirm you have identified the MOSFET pins correctly.

Remember, when you place the MOSFET into the holes in the top of the breadboard, when you turn the breadboard over to make connections, the MOSFET pins are reversed.
Take this into account and flip your thinking 180 degrees.
;)

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Take one of your channels that is failing to work.

Carefully trace out that channel and draw a good schematic of that channel, show it to us.

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Remove one of the failed channel’s MOSFETs off the board, put it into a solder-less breadboard, in a circuit like this, run the toggle sketch you just wrote to see if the MOSFET works properly.

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BTW, what is written on the MOSFET body ?

[LarryD]

Note to self, always check your resistor with an ohm meter before using it in a circuit.

[hk_jh]

@LarryD

18R

Edit

Triple check all resistor values with a meter.

I just checked again. All resistors ar ~6k8 apart of the resistor of mosfet 1 which is 18R and resistor of mosfet 5 which is 1k5

[hk_jh]

@LarryD

Confirm you have identified the MOSFET pins correctly.

I can confirm that

@LarryD

BTW, what is written on the MOSFET body ?

MOSFET of solenoid 1: FQP30N06L
All other MOSFETs (including mosfet of solenoid 5) : 8A28RL P30N06LE and is from here

[hk_jh]

@LarryD

Take one of your channels that is failing to work.

Carefully trace out that channel and draw a good schematic of that channel, show it to us.

EDIT: IMPORTANT UPDATE I've taken out MOSFET of Solenoid 1 (in which I have read 18R resistance). After I take the mosfet out I've read again the resistance value and it is back to be 6k7!! Does it mean the mosfet it self was broken??

Edit2: Important update 2: I've read with DMM the resistance of the failing MOSFET I taken out and I'm reading 18R resistance between Gate to Source which I guess should not be?

Edit3: Update 3: It is working! solenoid 1 has back to work after I replaced the MOSFET. Will do the same with solenoid 5 now

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Here is the strip board layout of all mosfet. I've blue the failing nosiest.

here is the schematics of all mosfet which is identical.

[TomGeorge]

Hi,
Did you check the resistors in circuit, or did you lift one leg to test them?

Tom..

[hk_jh]

In circuit itself

[TomGeorge]

Incircuit and you get values less than the colour coded values, tends to lead to faults in other components or track shorts.

Have you lifted the LOW reading resistors and measured their out of circuit resistance?

Tom..

[LarryD]

@hk_jh

EDIT: IMPORTANT UPDATE I've taken out MOSFET of Solenoid 1 (in which I have read 18R resistance). After I take the mosfet out I've read again the resistance value and it is back to be 6k7!! Does it mean the mosfet it self was broken??

Edit2: Important update 2: I've read with DMM the resistance of the failing MOSFET I taken out and I'm reading 18R resistance between Gate to Source which I guess should not be?

Edit3: Update 3: It is working! solenoid 1 has back to work after I replaced the MOSFET. Will do the same with solenoid 5 now

You are almost there !

Unfortunately some sellers are selling poor knockoffs.

[hk_jh]

I updated at post 190#

I've check all the resistors in circuits (with mosfet) and all of them were ~6k8 apart of at mosfter 1 (were ~18R) and at mosfet 5 (were 1k5)

I've removed those associated mosfets and checked those resistance again. Both were 6k8 as they should. I then replaced those two mosfet and then they worked as intended.

[LarryD]

@hk_jh

I then replaced those two mosfet and then they worked as intended.