Hello Chief Delphi!
Two of our Power Distribution Boards broke, and we think there might be a problem internally (might it be a broken component or similar). Does anyone have the schematic of a Power Distribution Board? We’d like to make an attempt at fixing it (if we can) before purchasing a new one.
Thanks in advance!
Our website has some good documentation.
Click “Power Distribution Board”
in that panel there will be general info, a PDF about getting to use it, as well as a PDF with the actual schematic of the PDB.
What do you mean by broke?
Also, beware of R65:
4.1.9.11 R65
The Driver Station software, cRIO, motor controllers, relay modules, wireless bridge, and batteries shall not be
tampered with, modified, or adjusted in any way (tampering includes drilling, cutting, machining, gluing, rewiring,
disassembling, etc.), with the following exceptions:
Please note that the Driver Station application is a separate application from the
Dashboard. The Driver Station software may not be modified, while teams are expected
to customize their Dashboard code.
A. User programmable code in the cRIO may be customized.
B. Dip switches on the cRIO may be set (applies to cRIO-FRC only).
C. Motor controllers may be calibrated as described in owner’s manuals.
D. Fans may be attached to motor controllers and may be powered from the power input terminals.
E. If powering the compressor, the fuse on a Spike H-Bridge Relay may be replaced with a 20A Snap-Action
circuit breaker.
F. Wires, cables, and signal lines may be connected via the standard connection points provided on the devices.
G. Fasteners may be used to attach the device to the OPERATOR CONSOLE or ROBOT.
H. Labeling may be applied to indicate device purpose, connectivity, functional performance, etc.
I. Brake/Coast jumpers on motor controllers may be changed from their default location.
J. Limit switch jumpers may be removed from a Jaguar motor controller and a custom limit switch circuit may be
substituted.
K. If CAN-bus functionality is used, the Jaguar firmware must be updated as required by FIRST (see Rule R68-D).
L. The First Touch I/O module’s firmware may be modified.
Note that if you are using the FirstTouch I/O module as part of the OPERATOR
CONSOLE, you should not update the firmware if the manufacturer releases a new
version. The new version will wipe out the FIRST custom firmware and your FirstTouch
I/O module will no longer function with the Driver Station software. If a team does wipe
out the FIRST custom firmware, it can be restored via the most recent Driver Station
update.
M. Devices may be repaired, provided the performance and specifications of the component after the repair are
identical to those before the repair.
Please note that while repairs are permitted per the FRC Game Manual, the allowance is
independent of any manufacturer’s warranty. Teams make repairs at their own risk and
should assume that any warranty or RMA options are forfeited. Be aware that diagnosing
and repairing COMPONENTS such as these can be difficult.
While repairs aren’t illegal, you are advised that they may be difficult.
Wally,
Are these older PDs? Exactly what are the issues you are seeing?
I second the question “What do you mean by broke?”. I also find it impressive that one could destroy one board, no less two :). Either that or you guys are just the lucky ones. Is it possible that they function but are just connected incorrectly?
- Bryce
Broke means “non-functional”.
PD board 1 - measured the output on the 24V cRIO connector and it reads 0V. Indicator bulb is not lit.
PD board 2 - measured the output on the 5V radio power connection and it reads 0V. Indicator bulb is not lit.
We have had another PD board where the indicator bulb did not illuminate, but the output voltage was correct.
Well, yeah. Those sound pretty broke to me… 
Do you have any thoughts as to whether the boards may have been jostled roughly or do you think it may have been electrical overloading? The regulated connections have over-current protection so assuming that was working maybe they took hard mechanical hits. I would be interested to know what you find out.
- Bryce
Chris,
There is a reverse polarity protection device for the power supplies. It is labeled Q12 on the schematic. If that device is open, then I would bet none of the power supplies would come up. There also is a circuit breaker in series with each of the 12 and 24 volt supplies.
If these are very old PDs then there was an issue that a capacitor was too close to the edge of the board. It sometimes would get knocked off and find it’s way into another area of the board. These devices are very easy to open up and inspect. Look for missing parts or smoke damage on the board. Also look for evidence of burned circuit traces.
Oh sure. One thing to keep in mind is that electronics run on magic smoke. When you let the magic smoke out they don’t work any more…
- Bryce
Al,
We did open them both to see if there were any obvious problems. No smoke damage and the conformal coating was intact. That’s when one of the electrical mentors asked for the schematics to look at, and the question was posted. Thanks to 3992 for the datasheets and schematics. I’ve printed them and will give them to the electrical mentor for use in debugging the problems.
As for why they stopped working… that seems to be the question of the day. PD board 1 was working last week, we were using it to test the new talon motor controller. The setup was taken apart and transported to Kettering University on 1/6/13 for the Strategy Dictates Design workshop put on by the EngiNERDS 2337 and returned to our shop. It may have been dropped/jostled/mishandled at some point during this time. We may never know. I will let the mentor know that a component near the edge of the board is sometimes the culprit for a PD to go non-functional.