power distribution board 24 v output

[mryeagle]

Interesting issue... robot powered up 24 volt unplugged dhows 24 v


Plugging in the crio... results in a 20 v reading....

Checked everything pluged to the crio and have no signs of volt loss... could the power dist board have a 5v loss???


Thoughts?

[Al Skierkiewicz]

Jeff,
Are you measuring at the PD or the Crio?

[F22Rapture]

Also, the battery is charged, correct?

[Mark McLeod]

What's the measurement at the PD power studs (not the wire connectors) when the 24v output is giving you 20v?
Is the PD's 5v power LED (for the camera connection) lit or is it out?

[mryeagle]

Batt fully charged
5V on
Camera power on

Were at ramp riot today and borrowed a new power dist boart
Which solved the problem....so now... what happened inside thr pwr dist board??? And or what did we do to get so Lucky?

[Mark McLeod]

I've seen those symptoms on PD's that had shorts, both internal from swarf, and in other cases an intermittent external short (caused by movement of an arm pinching wires) connected to one of the regular wago pairs resulting in a brown out. They read 24v until a load (cRIO) was applied.
We identified the troublesome external circuit by pulling all the breakers, then reinserting them one-by-one until the voltage dipped.
The swarf we identified by opening it up and clean out loose metal shavings and dust.

[F22Rapture]

I've seen those symptoms on PD's that had shorts, both internal from swarf, and in other cases an intermittent external short (caused by movement of an arm pinching wires) connected to one of the regular wago pairs resulting in a brown out. They read 24v until a load (cRIO) was applied.
We identified the troublesome external circuit by pulling all the breakers, then reinserting them one-by-one until the voltage dipped.
The swarf we identified by opening it up and clean out loose metal shavings and dust.

I'm going to butt in for a second here because I have a related question...

About 3 weeks ago we were doing a demo for one of our corporate sponsors, and the robot spontaneously stopped responding. The other night when we were troubleshooting (none of the technical people were at the demo) we found that the cRIO was not responding to anything whatsoever (none of the status lights lit up at all, including the power light). We checked the connections, nothing. We unplugged the wires and then used direct lines (no connectors) from the PDB to the cRIO, and nothing. We checked the battery, and it was fine. And then we used a multimeter to check the voltage on the 4-pin PDB connector, and found nothing. We checked inside the case for metal shavings, and there were none.

We have a 2 year old 8-slot FRC I cRIO.

Does this suggest that the cRIO is dead, or is there something I'm missing or something we're forgetting to do? And if it is dead, does anybody know what NI's policies are regarding repair or replacement of the FRC I?

[Mark McLeod]

The cRIO warranty is for 3 years from date of shipment by NI.

Have you, carefully, opened up the cRIO and cleaned that out, too?
I'd do that first just because you should probably do that periodically anyway.
Swarf working its way inside the case is a common cause of cRIO lights out, and they're pretty tough beasts, so a cleaning usually helps.

How to Clean the cRIO-FRC and Install Gaskets.pdf (http://team358.org/files/programming/ControlSystem2009-/How%20to%20Clean%20the%20cRIO-FRC%20and%20Install%20Gaskets.pdf) (ignore the gasket part unless you have them to install)

If you aren't seeing 4-pin power at the PDB without anything connected to it, then the problem is the PDB not the cRIO.

[F22Rapture]

The cRIO warranty is for 3 years from date of shipment by NI.

Have you, carefully, opened up the cRIO and cleaned that out, too?
I'd do that first just because you should probably do that periodically anyway.
Swarf working its way inside the case is a common cause of cRIO lights out, and they're pretty tough beasts, so a cleaning usually helps.

How to Clean the cRIO-FRC and Install Gaskets.pdf (http://team358.org/files/programming/ControlSystem2009-/How%20to%20Clean%20the%20cRIO-FRC%20and%20Install%20Gaskets.pdf) (ignore the gasket part unless you have them to install)

If you aren't seeing 4-pin power at the PDB without anything connected to it, then the problem is the PDB not the cRIO.

We did open it up and blow it out with canned air, however there were no metal shavings that we saw. And we tested the voltage on the PDB and got a good 24 volt reading. The warranty is good to hear though.

[Al Skierkiewicz]

There are a few things to add here. On older PD boards, there were some components that were mounted near the edge of the board. Abuse could dislodge these devices.
The 8 slot Crios have a internal fuse that had been known to fail with other electrical issues on the robot. If you are going to open the Crio, use a DMM to check for continuity on the fuse.
There is also a breaker in the PD for the power supplies. If there was an electrical fault that continuously tripped one of the breakers, it is possible it failed permanently. Documentation on the PD is available online on the First site. I believe it is in the KOP section.

[tr6scott]

If out of warranty, there you can look at the circuit board, by the power supply connectors there is a board mounted fuse there. you can apply power, and see if you have power on one side and not the other. I think the board nomenclature made this pretty obvious too, like labeled something like "F1". We have revived two cRio's by piggy backing a second fuse on top of the blown one. Fuses were found at mouser.

I don't have the details, one of the mentors that does electronic repairs for a living, had some in his car that were close enough in size, and we used those, but I did find the right size and form factor at mouser.

If needed I could probably open one up and take a pic, we had the students do the solder job, with his oversight, so it isn't pretty.

Just know even if it is not under warranty, with very little time and expense, it can be brought back alive.

[mklinker]

What would cause the 24 v output from the power distribution board to be dead while all other outputs seem to be live. We are getting no power to the crio and the 24V indicator light is not coming on. Ideas?

[Al Skierkiewicz]

In nearly 100% of the cases, there is a whisker touching the negative and positive 24 volt leads together. Pull the connector out of the PD and see if the 24 light comes on and if you measure 24 volts at the connector. That will tell you if the PD is OK. There is some protection circuitry in the PD that could have failed if you had somehow exceeded the power supply specs. If you are using 24 volt solenoids and therefore are using the Crio power supply in two places you need to check all wiring. If the PD is good, try powering the Crio by itself (i.e. remove the power to the solenoid module). If that is OK then look to something wrong in the solenoid module wiring.