Has anyone run into this issue? Was testing something on our robot and realized that the radio power module was malfunctioning and melted. Didn’t trip any breakers and students claimed that power pins weren’t hot to the touch.
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Was it close to any other components that could have gotten hot? That board looks weirdly clean for a board hot enough to melt plastic. Not saying its not the RPM, it just is interesting.
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Was it plugged into a 40amp breaker? What guage wire were you using on it? If you feel the ground wire on it while on does it feel hot? That will show resistance in your loop.
Well, that’s exciting!
Naturally, Rev will ask you to send them the unit, so that they can do proper analysis. But as long as we’re here, this arouses my curiosity.
Generally, in a power supply circuit, one expects a switching element to overheat in the event of overload, or maybe a filter in certain topologies; usually this means a FET, or occasionally a small coil.
In this case, you have obvious melting on the area of the case farthest from any components. U2 there is the obvious candidate, but it’s kinda centerline on the PWA, and the melting is noticeably on one side. Okay, sure, if the module was mounted vertically, convection could play a part, but I’d still expect to see a hotspot on the bottom of the case near U2, if that were the culprit.
I feel like you’d almost need a internal trace along the side of the PWB, acting as a very localized heating element, to get this kind of signature.
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Was it near a very hot compressor by any chance?
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15 amp breaker on mini power module, I think 18 awg? Can confirm tomorrow. Didn’t feel ground wire, but the board side pin felt cool.
Near Ethernet switch that wasn’t hot, pneumatic hub that wasn’t hot, compressor that was off for the whole day
There is some melting on the plastic bracing above the capacitors(?) transistors(?). Mounted horizontal
Do remember to send an email to REV support before sending the unit… support@revrobotics.com
(And just for good measure… @Greg_Needel, just so he knows to expect the email 
)
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I agree with the assessment made by @CarlosGJ. @kellyissure please post a photo showing the radio power module where it was installed.
Do you know for certain that the compressor was never run with the RPM nearby on this machine (at any point in it’s lifetime)? Even though you just noticed it then, perhaps it had been like that for a little while.
Sounding (and looking) a lot like the RPM accidently touched the hot compressor at some point, causing the melting.
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Might be a silly question, but was someone using a heat gun nearby to bend Lexan or heat shrink some wires? It could be melted from an external source.
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In this case, the size of that switching FET vs the inductor tells me the inductor would saturate and get toasty before the FET gets so upset it radiates enough heat to melt plastic. I find it very hard to believe the melting is due to anything on this board, especially given breakers didn’t trip and the power pins weren’t hot.
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Does it still work? If any of those electronics had generated that amount of heat, it shouldn’t.
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What does the inside of the case look like in the melted area? The outside looked like it not only melted but burned a bit. If it were from internal heat, the inside face would look even worse. If external, not as bad.
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We noticed the damage once we lost comms, not sure if they would come back if plugged back in
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It also doesnt look like the melting is anywhere near most of the components i would expect to be able to generate heat. if im looking at the images correctly, its on the side of the PCB with the Rev text, away from most of the pcb components. Not to mention that amount of heat would usually show some kind of damage on the board.
Like many others in this thread we suspect that the cause of this was external to the RPM not internal. Regardless of the cause please reach out to support@revrobotics.com so we can fully understand what is going on here.
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This caught my attention because we too lost comms randomly last night and we use the RPM.
The wifi showed up, but said we were unable to connect to it.
How the event went:
- Enabled
- Programmer drove a bit to make sure nothing seemed off
- Disabled (did not turn off or change locations)
- Handed off to the driver for some practice when they got there
- Lost comms
- Tried a hard reset (waited a few minutes)
- Noticed the wifi was there but would not allow connection
- Left on while looking over the wires (no issue found there)
- Connected
- Practiced
Do you have any pictures of it wired up on the robot?
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