Tom, Mike, all,
Thanks for the suggestions. Hot glue it is. I’ll have our electrical team review the diagram in the earlier post and the ‘hot glue’ ideas. I’m putting the glue gun in my backpack now to make sure we have one tomorrow night.
We’re not in panic mode on this yet. Just don’t want to head that way.
Again, thanks for the suggestions.
-Ted
Ted,
After a few days, post an update if this worked. I’d be interested to know if this is an issue with the new radios…
Regards,
Mike
While on the subject of the DLINK radio…
<R38> B. The radio power feed must be connected via the 5V converter (model # TBJ12DK025Z) to the marked 12 Vdc supply terminals located at the end of the PD Board (i.e. the terminals located between the indicator LEDs, and not the main WAGO connectors along the sides of the PD Board). No other electrical load can be connected to these terminals (please see the 2011 Robot Power Distribution Diagram posted online at www.usfirst.org/frc/kitofparts for wiring information).
I just discovered rule this yesterday afternoon while looking for something else. Ay-yi-yi! We’ve been running ours directly off the 12Vdc terminals. It still works but I hope we haven’t somehow damaged it. Maybe everybody else but us knew this but you might want to check your robot to be sure that the converter is being used to provide the correct voltage to the radio.
I doubt if it was damaged. I think the main reason for powering from the dedicated terminals is to provide a kind of UPS function. The battery voltage can crash to very low levels when you put large demands on it (like four cim motors at near stall…).
FIRST is trying to make the communications as robust as possible.
Change the wiring to their recommendations and move on…
As long as you used the 12v-to-5v converter it’ll survive.
The real problem with using the red/black wago connections for the radio is that a significant drop in battery voltage, e.g., full-power robot pushing contest, will risk resetting your radio.
The special 12v connector (and the 24v cRIO power) are protected against voltage drops to avoid resetting either one of those devices during a competition match.
This probably isn’t your problem, but just for the record we had hellish problems last year losing connection. This persisted through two regionals. Our drivers spent more time with their hands in their pockets than on the controls.
After getting back and experiencing the same problems on a completely different robot we investigated further.
We found vigorously shaking the radio had NO effect, but gripping it lightly on the top and bottom killed it instantly! We took it apart and looked at it under a magnifying glass for aluminum shards, cracked traces, anything. Finding nothing we put it back together and it worked just fine. Go figure.
That’s why I’m a mechanical guy.
I just got through purchasing another DLink because our team wired it directly and fried it. $107.00 from Office Depot because we didn’t RTM! Please learn from our eagerness to get the robot rollin’!
If you are loosing something when you run over bumps check these things…
Any body ever heard of a converter that is bad? On our converter, when we power 12v in we get 7.3v out. That doesn’t necessarily concern me, what does concern me is that when we plug in the power to the D-Link we get nothing; we tested voltage, and we exactly get 7.3v out of the plug (as expected - the plug that came with the D-Link gives 5.2v in the same orientation) yet the D-Link is only pulling 2mA from the converter. Something seems bad here…
We do know:
If we bypass the converter, everything “works” (we accidentally did that before adding in the converter). This tells me the extra plug we bought (same size as the one that came with it) fits and works.
If we plug in the power cable that CAME with the D-Link, everything works fine (even after the fact).
With the converter in-between, voltages look fine but we’re pulling almost no current.
Does this sound fair to say the converter is possibly bad?
-Danny
That does sound suspect, I remember when we wired ours up I probed it with the multimeter before connecting the radio to confirm polarity and it was reading around the expected 5V under no load. Some SMPS don’t work well without load, but if you’re connecting it to the router and not getting anywhere, that’s weird.
Are you sure your router is good? It seems strange it wouldn’t try to pull more current. If the problem was in the converter not delivering more current the voltage should take a dive.
Matt
What about that button on the side of the D-link? (I believe it has circling arrows) Is it getting pressed when the robot hits a bump in the carpet? Could that be resetting the D-link in some way?
Last year we had a similar problem with communications. We lost it every time we went over a bump! It is still a mystery for the most part, but I am sure that it was the terminals to the battery. The few times we didn’t lose communications were matches where we cleanly redid the leads to the battery beforehand. I’m sure the battery box was also to blame. It was solid and kept a strong hold on the battery, but the whole thing swung around as the robot moved, which probably loosened the leads.
Last year we velcroed our black bridge on, kept the battery in place with surgical tubing, screwed in a bolt for the battery connector end attached to the Power Distribution Board. I don’t think we had any problems last year during a match related to communication.
Danny,
There are two things that concern me. The first is that the DAP works on 12 volts when you bypass the convertor. This should not happen, it should blow up the DAP at 12 volts. The second is that you are measuring 12 volts into the convertor but only getting 7.3 volts out.
I have to ask (even though I know the answer) is the convertor wired exactly according to the drawing. The +12 volt radio connector on the PD wired to the convertor input leads and the DAP connected to the output leads?
That’s what I thought, too, and nearly had a heart attack when I was reviewing the schematic and saw the need for the converter. Eric VanWyk looked over the components inside the DAP, and he says all of the power components should be capable of handling 12v but the manufacturer of course will not sign off on that (for good reason). After plugging in the DAP into 12v, I was concerned I may have fried something, but when we plug the DAP into the wall using the supplied transformer/cable it works flawlessly (at least as flawlessly as we can tell). I think we’re going to get a new DAP and have it stand-by just in case something turns up, but we cannot find anything wrong with the one we have.
That’s a fair question, but I wonder why you said, “only getting 7.3 volts out” - when I saw 7.3v when we first started playing with it I thought that was pretty suspect since I figured we should be seeing something around 5v since the converter is a 12v/5v converter. We absolutely have the converter’s 12v input line connected correctly to the PDB’s 12v output just to the left of the 24v line for the cRIO (and we’re correctly measuring 12.3 volts from that line), and then the supposed 5v output (from which we’re measuring 7.3 volts) from the converter is wired correctly to a connector that plugs into the DAP’s power plug (EDIT: Yes, and we have a fully-charged battery).
It’s just that when we try to power the DAP through the converter, nothing happens - no lights, no nothing, and while plugged in the multimeter says 2mA when I cut one of the wires and put the multimeter in series between the cut. But, when we unplug from the converter and use the supplied walwart (plugged into the wall, of course) everything works great on the DAP.
-Danny
Just curious, are you able to measure the current draw and the voltage at the same time? it seems odd that you’d be pulling so little current at 7.3V. Like I said before, I’d expect the voltage to dive if the converter was damaged, other than that I would agree it sounds like a faulty converter.
Worst case, you could design an elaborate mechanism to trail an extension cord to your robot 
While one multimeter was reading the 2mA with the plug trying to power the DAP, we used another multimeter to verify the voltage going INTO the converter, and saw we were still getting 12v INTO the converter - I remember saying out loud, “now we need to measure the voltage coming OUT of the converter,” but because the “other” solder joint was still heat-shrinked for the output side I think it was quickly forgotten. Thanks for the reminder, I’ll do that today.
-Danny
If the voltage is low as I suspect you may have a bad converter, or when you attached your ends and did the heatshrink you got a short, and the converter is shutting down to prevent damage. (Do we know if it has this feature?)
If it doesn’t have such a feature it might be that you have a bad converter because of a short damaging it. I’d definitely double-check all your connections in this case and make sure there are no shorts and see if that resolves your problem.
If you measure a high voltage (like 7.3V or so) at that current… I’m flabbergasted?
I wouldn’t personally be too concerned about the 7.3V, some SMPS and even linear regulators float high without load, just because it didn’t occur when I checked it doesn’t mean it won’t.
Do report back please, I’m curious how this works out,
Matt
Tis a puzzlement.
I would have guessed that the failure mode on this device would a zero volts or 12 volts. Since it is not zero, 7.3 seemed to be low. I have not found any real data on this device on the manufacturer’s website so there is no way to point at a particular type of convertor. So I am going to say it is defective but this is what I think might be the failure. If it is a switching type of regulator, the frequency might be so far from design that the output is not able to generate any current. Have you looked at the output with a scope? I am guessing there is a fair amount of AC voltage on the output and your meter is measuring that and interpreting it as 7.3 volts DC.
Of the teams that have reported that they hooked up their DAP to 12 volts and killed it, some may have reversed the voltage prior to the connection. Maybe you are just super lucky. With that kind of luck, I hope we don’t play against you this year.
Hmm, interesting theory, I hadn’t thought of that. I’m quite curious now, I wonder if they have a scope.
Matt