Need help with diagnose vesc HW (CANBUS issue)

Allright, I´m in need of some help with diagnosing vesc hardware related to CANBUS. I can´t get them to communicate with each other and I´m 100% sure the settings is OK in bldc tool…

I shorted 2 of my vesc´s (4.12 and 4.10) when connecting canbus wire while the system was on. Both of them shut down the second I connected them. But the 4.12 rebooted itself after 10-20 seconds, while the 4.10 didn´t power on. I had to replace the CAN receiver on on that one.

I have 1 new 4.12 vesc (never used) that I compare the readings I get from multimeter in “diode” mode… I get a signal through canbus High and Low so there´s nothing wrong there.

On the SMD components :

Vesc 4.12 (new)

R401 - 162 C401 - 1176 R402 - No reading

Vesc 4.12 (shorted)

R401 - 111 C401 - 062 R402 - No reading

Vesc 4.10 (shorted) Replaced U401 myself (probably the reason this one is not working)

R401 - 162 C401 - 1182 R402 - No reading

Any other components that is related to canbus communication? C401 on the shorted vesc seems to be off… Could that be the problem?

Regards. Rob

i had a bad cable or 2 and decided to split ppm… everything i have read says to connect can prior to power, im absolutely sure u already know all this, sorry for the useless post, i hope u get everything sorted!! =)

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C25 is good. What do you think about c401 being 062? I read somewhere that if it’s under 150 it could be a short. Same with R401 being 111?

Sorry to hijack this thread, but the issue is related. I have two new VESCs that will not connect through CAN. One of them has a faulty BEC. When I try to power a receiver from 5V out, the voltage drops to 1.2V. The second VESC is fine and remains stable.

Is the CANBUS chip depending on the same onboard BEC that is outputting 5V for PPM?

It’s a capacitor, so you can’t really measure it with the a multimeter and inside a circuit, you need to unsolder it and use a proper capacitor meter, because if it’s still in the circuit other components will interfere with your reading. (the procedure that I post for C25 is to measure a dead short, and you need to read 0000). As for R401 the resistance is 100 Ohms, so your reading are good.

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Ah okay I see. Thanks for educating me :smile: I’m stubbern as hell so I will go out and buy a capacitor meter and start to unsolder the caps… C401 is it the only cap that is related to the canbus? To my understanding R401, R402, U401 and C401 are the canbus related components.

OKay I give up. Split ppm until next summer :smiley: Thanx for your help guys