OM5P-AP radio failing... no lights

[PhilBot]

We had a harrowing practice last night. In the end we had two OM5P-AP radios that don't show any lights when they get plugged in.

We took our newly wired robot and tested it via USB. All ok.

When we switched to the new OM5P-AP radio things didn't go well.

We had configured two radios on our prototype robot without issues. NOTE: They both worked fine driving around, connected to a laptop wirelessly.


We switched the radio to the new robot and powered it up. All the lights came on and appeared to do a normal power sequence, but it wouldn't connect. Somewhat frustrated, we switched to the other radio and it connected an ran for a few minutes while they got familar with the production bot. After taking a defende, the radio dropped out.....

No problem... we assumed a loose connection was the issue. We jiggled the connector and things seemed a bit flakey, and then the lights went out and stayed out. Suspecting the barrel plug we tested the voltage and it was 12V.

We plugged the radio into the protobot and it was still dead. The first radio got plugged back in and it lit up, but still didn't connect.

So... diagnosis... radio had failed. Hmmmm.

We checked the power wiring, and there is only ONE thing connected to the Voltage regulator module... the radio. The cable is about 8" long. No real opportunity for problems.

We switched in a third radio.

This one connected,and ran for a while and then ALSO died in the same way. No lights any more when plugged in.

As a final test, we openned one of the dead radios and used a meter to probe the terminals on the power input connection. There was a solid 12V present.

The only thing we could think of was that we were getting spikes on the 12V line, but this seems very unlikely.

Anyone else have anything like this, or can think of a failure mechanism?

Phil.

[rich2202]

Originally Posted by PhilBot

The only thing we could think of was that we were getting spikes on the 12V line, but this seems very unlikely.

My first thought is that it could be your VRM. Is there a log of VRM voltage anywhere?

[Joe Ross]

Originally Posted by rich2202

Is there a log of VRM voltage anywhere?

No

[droswell]

We have the same failure - drove our bot over a defense and it shut off. We thought a loose connection as well, but looked and it was connected. Unplugged, and plugged back in.

No lights. Checked and found 12V on the barrel connector. Checked again - still no lights. We bought this second one from Andymark and put an RMA in. Hopefully this isn't a common issue.

We've wrapped our new radio in foam to protect against shock, but the airflow will be reduced. May have to get creative...

[PhilBot]

Well, we lost another radio.

The build team swapped out the VRM (in case that was the problem), and proceeded to drive for a while, until the next major bump caused the radio to lose it's lights. Now it's dead.

We're now on our 6th and final radio (I don't even know where they all came from, but they must have been a week one bulk purchase).

That's 4 dead radios (no lights) and one that won't configure properly.

Phil.

[AllenGregoryIV]

We have one radio that is died in a similar fashion during our practice last night. Haven't found a root cause.

[AllenGregoryIV]

I took apart our radio that wasn't powering on to see if there was anything I could noticeably see as a problem. There are only two screws under the front foam feet. The screws don't need to come all the way out just loosened then the top is able to pop off easily. There wasn't any heavy swarf or any noticeable burnt components. There are three antennas in the radio one along the front and two along the left side when looking at from the rear.

I had to cut/pry some adhesive off to remove one of the antenna connectors to get to the bottom of the board pair (their are two boards, one main board and daughter board in a slot). Once I did this I was going to check the voltage at the input barrel but when I plugged it in the light just came back on. Not sure what happened but it doesn't seem like dead radios are dead forever which is a good sign. I still worry about using this one on our competition robot.

In summary opened it up and after plugging it in it started working again without me intentionally fixing anything.