220AC: Left wheel motor not at full power

[Hopptjohej]

Hello, sorry for writing in English
The left wheel motor on my AM 220AC does not want to spin at full power.
When running "motor test" in the tool menu, both wheels spins but the left does not always start and lacks power.
If I change the motor cabling between right to left, the fault moves to the other motor, indicating a faulty motherboard. I have replaced the MOSFET circuits for the left wheel but the error remains.
When I measure the voltages with a standard voltmeter on the phases of the motors, the right and left motor MOSFET outputs values differ (1.5V versus 3V). See linked picture
Any suggestions for continued troubleshooting?
[url https://www.dropbox.com/s/t7wz3tt7oojm90u/PXL_20210511_3.jpg?dl=0]
Thanks

[Razmoket]

Hi
There's a problem in the circuit before the mosfet. Resistors 1ohm, 10 ohm and 560 ohm are usual culprits. No need to disassemble to test them.
There is no chance measuring PWM output for 3 phase brushless with a voltmeter. Only a scope can help.

If resistors are not in cause, you can send me the board, as the problem can then have various causes and needs debugging with appropriate material.

[Hopptjohej]

Hi, I guess you mean these resistors.
[url https://www.dropbox.com/s/1mi7u0gsoh6yi8n/PXL_20210511_4.jpg?dl=0]
When measuring them, I found one 10 ohm that was out of spec.

Regarding the 1 ohms... I guess you mean the 8 in parallel, I have the same value (0.21 ohm) on both motors. (but when I calculate 8x1ohm in parallel it should be 0.13 ohm)
This mismatch might be the difficulty to measure the small value.

Yes I know ;) PWM on an voltmeter.... Just a quick and dirty “comparative measurement” between the motor drivers. If I need to go deeper I will probe with the scope.

I'll try the 10 ohm replaced resistor first, probably in the beginning of next week, I will post the progress here.
Thanks @Razmoket for your support

[img https://ibb.co/1qTrQTv]

[Razmoket]

For the 1 ohm, don't worry, you're indeed measuring the resistance of your meter tips. But, anything below a few tenths of ohm is ok.
10 ohm out of spec: system is not very picky. Usually, out of spec = more than 10% deviation.
Check also the 100 ohm in the nearby.

[Hopptjohej]

Thanks @Razmoket for your support.
It was one of the 10 ohm resistors that was broken.
After replacement the AM220AC is now working again.

[Browning45]

Hi

Apologies for bringing this old thread back to life, I have the exact same problem after a big rainstorm. Left motor hardly turning, if I swap the motors around the left motor is fine. Could be the resister. I don't own a scope, just a multimeter.

Does anyone have any suggestions on how to fix this?

Thanks

Ian


[ChatGpt Translation]
Salut

Je m'excuse de relancer ce vieux sujet, mais j'ai exactement le même problème après une grosse tempête de pluie. Le moteur gauche tourne à peine, mais si j'inverse les moteurs, le moteur gauche fonctionne bien. Cela pourrait être la résistance. Je ne possède pas d'oscilloscope, seulement un multimètre.

Quelqu'un aurait-il des suggestions pour résoudre ce problème ?

Merci

Ian