Somehow we managed to fry the 5v regulator on the digital sidecar, can someone take a picture of the digital sidecar showing the chips so we can try to repair ours since AM is out of stock, we would like to have a spare digital sidecar for the championships.
Kelly
Those supplies will “play dead” if their output is shorted. Sometimes the board will spring back to life once you clear the short.
If it is actually dead, do you know what caused it?
Here is the link to the design files: http://www.usfirst.org/roboticsprograms/frc/control-system-resources
It’s definitely gone, we opened the case and there’s half a chip left, I’m not sure what happened, I just know it did
Thanks for the link, the diagrams show are for Rev. 7, the 2012 sidecar has a Rev.8 pcb and the component we blew is not shown in the Rev.7 diagrams. Anyone know where we can find the layout for the Rev. 8 pcb. The component that we blew is just to the right of the smiling sun, it is a surface mount IC with 8 contacts.
Kelly
Here’s Rev 8
SideCar_v8.pdf (1.47 MB)
DSC package.zip (1.67 MB)
SideCar_v8.pdf (1.47 MB)
DSC package.zip (1.67 MB)
Thanks, I’ll post if we were successful in reviving the sidecar
They should be nearly identical, especially that circuit. You can petition FRCHQ to post the correct schematics - I’ve tried several times and failed. They were posted correctly last year, but this year’s schematic regressed a bit.
It is a TPS5431 or TSP5430 if I recall correctly. The parts are pretty much identical except for maximum input voltage, so the manufacturer selects each year based on availability.
I’d love to see a photo of what happened. I’m specifically interested to know whether Q1 or U7 were also damaged.
I’m a bit confused though - you indicated that your 5V rail was damaged, but that U3 was the one that is missing pieces of itself? That should have taken out the 6V rail instead…
There is very little smoke damage but this could have occurred with a gate to source short. It could also be a crush break. Eric, have you seen this type of damage with a voltage reversal?
Thanks Mark!
Kelly - Q1 normally provides protection against reversed power. A huge pulse of current can damage it in the way shown. This could be the result of a chassis fault (motor current returning through the DSC), or from wiring the power backwards coupled with an ESD event (ESD can blow the gate and disable the protection).
Note: This may be a mildly dangerous repair. Please test with a bench top supply limited to less than half an amp, and keep an eye on the current draw. Testing with an FRC battery runs the risk of a small fire. On occasion I’ve had parts blow off the board while testing similar faults, but that only happens when I’ve bypassed at least one more layer of protection.
Before going through the effort of desoldering Q1, try shorting around it by plugging power into the usual connector and power return into one of the PWM power return lines. If it comes up correctly, replace Q1 and throw it on a non-competition bot. Otherwise, it may be irreparable.
Yep, usually in combination with an ESD event. One of the tests I performed in the lab was to apply reverse voltage and then hit the power line with 30kV from an ESD gun. Q1 would normally pop like Kelly’s picture.
I expect us to have the Digital Sidecars in by early next week, if not this Friday. Just FYI so you know you can get a new one for champs if you need it.
