Hi all -
My son has made great progress building the lowrider by himself. However, along the way he’s managed to short/fry/“break” a few boards (Rambo & Jackpots).
Any tips on how to best troubleshoot wiring issues without shorting out boards? Do we pull power every time we touch a wire going into the board?
Any best practices would be greatly appreciated.
Yes, most definitely. 
So here is the link to the control boards for docs available.
it links to the jackpot board, but if you look others are on the left.
https://docs.v1e.com/electronics/jackpot/
how do you know it is shorted?
Do we pull power every time we touch a wire going into the board?
Never disconnect or connect a wire with the board powered. With that said, Rambo boards are very robust. I’ve read on the forum about people making some serious wiring mistakes, and the Rambo board comes through unscathed. Before tossing the Rambo board, I suggest you do some troubleshooting. The issue may just be a blown fuse, and easily fixed. Or, if you have the endstops wired wrong, you will short out the 5V rail, preventing the board from running. The one big thing you want to avoid is unplugging the stepper wires while a stepper motor is running. This can blow a stepper driver, and the stepper drivers are not easily replaced on the Rambo board.
If you want to troubleshoot either of the two boards to see if they can be fixed, the forum is a friendly place to get ideas and feedback.
Even if the troubleshooting leads to the conclusion of a blow board, the process of figuring that out might be a good experience for your son.
Another source of blown boards is manually moving a carriage too fast. Now I hear you ask “how fast is too fast?” and the answer is when it blows the stepper driver it was too fast!
The stepper motor acts as an alternator if you manually move it and that voltage has to go somewhere!
All the above. If you don’t have one get a multimeter. It has a million uses, but the continuity feature will help you test fuses, grounds, and making sure you are wiring things correctly.
I agree with the “all of the above” comment. I did get the multimeter advice a couple years ago, and it’s so useful. Now I’m considering an oscilloscope. (I’d suggest a decent multimeter since you need to trust its readings.)
It is surprisingly easy to move a stepper fast enough to turn on an LED on a control board. If you’ve done that, you’ve moved it way too fast. Especially with belt systems, it’s very easy to induce the current.
I also check all my stepper motors so I understand the connectors for the coils (easy with the continuity function on my multimeter.)
I’d also suggest keeping a few extra stepper drivers around. If a particular motor is giving you problems, you may find that it’s just the driver that’s fried.
Since you mention you’ve had a few incidents, it might be worth checking your power supply and ensuring it’s providing the correct voltage for the board. (Again, multimeter.)
Came across this advert in my inbox today. I can’t say from a practical experience how good it is but Fnirsi is considered by many to be a decent make. It has sufficient capabilities for basic faultfinding in this environment and at $24 it is a steal!
There’s some good tips above. Another thing that might be helpful is to go back over the ‘blown’ boards with the forum and we can perhaps help figure out whether it’s destroyed or not.
Some failures- like hooking up power backwards, or shorting endstop +5V to ground are obvious major failures when they let out the magic smoke and burn a board- but many other things would have left boards still intact if they were properly troubleshot.
There’s even a forum thread about that…
The place the forum sees the issue of grounding 5V the most is in endstop wiring. Fortunately for the Rambo and the SKR Pro boards, there is protection circuitry on the endstop wiring that saves the pins. I remember one instance where the board appeared dead, and just unplugging the endstops brought the board back to life with no damage. We’ve also had instances on the forum where we’ve managed to salvage a board by reassigning a dead endstop pin to a new pin.
Coming from building Arduino projects, where every grounding mistake results in either a dead pin or a blow voltage regulator, I was blown away the first time I saw a Rambo board survive mis-wired endstops.