our team had some electrical issues during the season. suspected it was the pdp and opened it up to find a burned trace.
The one next door is looking bubbly, too.
Can you provide details of your drive train and the failure circumstances?
Or was this the climber circuit?
I’ll second Richards statement. If you could give the scenario of how this happened would be great. In theory, this shouldn’t happen because of the fuse but in reality it did happen so any detail about what lead up to this would be really, really nice.
As noticed, it looks like the trace below the burnt one looks bad, possible clue?
Interestingly, we never used that slot. We had some electrical issues at our first regional, so I looked at the driver station logs. I found that this slot was pulling large amounts of current with nothing plugged in. I suspected it was the pdp but wasn’t able to check it until after the season because the pdp wasn’t in a very accessible location.
Nothing was ever plugged into the slot for the life of the robot, and this robot was supposed to use a new pdp (with it being the competition robot), but we might have installed a used one by mistake.
Is there any circuit-circuit continuity (shorts) on the board?
When you opened it up, did you notice any metal shavings inside the casing?
No, the inside was pretty clean
Not even a breaker, I presume?
This trace looks like it’s for the negative connector on circuit 3; is this correct, or is it for the positive on circuit 12?
Snatching at straws: which adjacent/opposite circuits were in use, and did any of them show anomalously low current draw for the application?
Breaker was in at first, but I removed it when I noticed the strange current draw. Removing the breaker made no difference. It was for circuit 12.
All surrounding breakers were used. Don’t remember about the current draw of the other circuits. I can check when I’m near the driver station laptop later today. I’ll post the logs if anyone wants to see them.
When you say nothing was plugged into that slot, was there absolutely, positively no wire inserted into the BLACK Wago connector? If you are very, very certain that someone didn’t accidentally use the BLACK Wago connector on that slot then that opens it up to going down the circuit to circuit short scenario.
When it comes to the circuit to circuit short, be on the lookout for any possible debris that could have fallen into the PDP. For instance, I dropped a blob of solder into our PDP and it ever so nicely soldered itself to the fuse connector making it impossible to insert said fuse (the boss man wasn’t happy with me) . That blob of solder could have just as easily shorted something inside.
In short, make sure someone didn’t do something silly, then look for debris.
Now that I’ve got a better look at the pic, I see that the burned out area is labeled “SHNT12”. Is this the shunt for the current meter? If so, breaking the shunt might cause the current meter to report current flow just for leakage through the insulation. I haven’t found an internal schematic for the PDP.
The clue that the position had a breaker inserted, but was not used, when all the adjacent ones were in use raises my suspicion level that the PDP trace was burned out early (likely pre-season), and something was moved away from that circuit because no current was flowing.
Edit (forgot): also, on the circuit board at the lower right (which includes the CAN connectors), on IC5 (the largest chip), is there a flake of something on top of it, or is it damaged?
The broken track next to SHNT12 looks like what you would get with a short time (say under 1~2 seconds) overcurrent that quickly vaporized the copper track. Is there any copper “plated” on the plastic cover over this spot, on the vertical surfaces of the red and black Wago connectors right next to it or on the connectors for the breakers on either side? I am unable to see any sign of charring of the board material under where the track used to be or around the break in the track.
I’m gonna be “That Guy” here… This thread is fascinating and all, but if you can’t find anything that’s obviously user-error, then contacting CTRE is a great next step (if you haven’t already). Core FRC suppliers are generally pretty responsive to teams…