Problems with IR Board

[T3_1565]

We haven't tried ours yet, but perhaps your broke in shippment?? Also, what if they were meant to work (ok so its a long shot) does anyone have their's working perfectly???

I'm going to try ours tomorrow!

[keen101]

"I broke" our board today.

It was working fine, and then all of a sudden.... nothing worked. It suddenly got quiet.



I suspected the 5V 78LO5 was bad, so I asked my dad to help me diagnose the problem. Sure enough the regulator was bad. So my dad helped me find a suitable and more robust replacement. We put in a new regulator, and now it works great again!

...My advice to anyone with a quiet board, is to check the regulator.

[MrForbes]

What voltage were you sending to the board when it fried the regulator?

[keen101]

If your question was directed at me, then here's my answer...



I was using a 7.2v back-up battery.

Doesn't seem very likely that that would fry it.

Static electricity? I was being careful in regards of using it in a static free environment.

My dad said maybe it was half (over) heated when they assembled the board. But, he even had doubts about that. He seems about as bewildered as I am.

[ChuckDickerson]

Yep, that's the problem. The voltage regulator is dead. 9V battery in, nothing out. So, should I:

a) Try to repair it? Implications: We may make it worse!, Is it even legal to do this before build season or even at all?, What voltage regulator should I replace it with and where to get it?

or

b) Get it replaced? Implications: Where do we get a new board?

[Bharat Nain]

It looks like there are a few issues with this. I would HIGHLY recommend letting FIRST know about this ASAP. This way they can hopefully figure out a solution and check to see if there is a pattern with the problems. We are yet to get ours...

[MrForbes]

Originally Posted by keen101

I was using a 7.2v back-up battery.

Doesn't seem very likely that that would fry it.

Not from overvoltage, at least!

Thanks for the reply....I wonder what's going on....

[T3_1565]

my thoughts IT'S PART OF THE HINT!!!!!! Quick somebody find something out on 5v regulators!!! ()

In all seriousiness though We are going to try this

[keen101]

Yes, it does seem strange that almost everyone who has a problem with the board is an issue with the 5v regulator.

Perhaps a design flaw. I shall e-mail someone from FIRST teams, to take a look at this page.

...as for options... I say try and fix it. Mostly because It could be cheaper than shipping it off to FIRST to get fixed. and also because I have no idea where you can get a new one at this time. Maybe try e-mailing IFIROBOTICS.com. Besides, you'll probably have access to order a new one from ifirobotics later.

We used something like a L809h. Maybe not a perfect match, but it fixed the board, so I'm not complaining. So, you should probably try and get an L805, otherwise improvise.

Usually I would not recommend trying to fix electronics from FIRST (ie. camera board), but in this case... I have no idea if there any kind of warranty that could be void. I would assume there is no warranty. That's the problem with releasing cool electronics as a game hint. You virtually have no knowledge about the device.

[Mark McLeod]

IFI isn't in the production or supply loop on this IR board yet.

For technical assistance I'd talk to Ben Wrightsman at Diversified Systems Inc. the manufacturers of the board.

For a replacement we'll probably have to go through FIRST.
I have a message in to FIRST and will let you know what I discover.

So far the reported failures are quite small in regards to the 1500+ boards produced, so I'm hopeful it's a less than 1% failure rate. Ben told me they sampled boards coming off the production line and the samples all passed, but not every board was tested due to the time constraints of the Christmas rush.

P.S. Based on keen101's experience it does sound as though teams should run these for some time to make sure they catch any marginal failures early.

[Kevin Sevcik]

EDIT: Disregard the next paragraph...

I'm thinking this might be an oversight in the circuit design. The 78L05 series of regulators are rated for 100mA max output current. And the IR manual claims the circuit draws 100mA when an LED is on. Granted, that's a transient draw and the things are rated for occasional current peaks above that, but if it's been derated from overheating during the soldering process, then it could be marginal.

Of course, something could have just been shorted while you were testing it or something. At any rate, you should be able to find a 78L05 regulator of some brand at a local electronics shop that actualy carries things like resistors and caps and such. If you can find a 7805 or 78M05 regulator in a TO-220 package it'd probably be hardier, but you'd have to really try to jam it in to the same footprint, and heaven knows if any of this will be legal come kickoff.

EDIT: Whoops! I must have misread the IR manual, current draw is certainly not close to 100mA....

[keen101]

as far as how mine died... It shall probably always be a mystery.

Maybe something shorted, but I think overheating is more likely. I had been playing with it for over an hour. Enough time to overheat?

Besides... I didn't think anything could short out on an anti-static bag. Who knows, maybe my finger slipped and shorted something. seems dubious though.

[MrForbes]

beeing over 40, I had to take a picture of the part to be able to read the writing on it!

[Daniel_LaFleur]

Originally Posted by squirrel

beeing over 40, I had to take a picture of the part to be able to read the writing on it!

Looking at your picture, the part is made by National Semiconductor (thats the funky looking 'N' as the first letter) .

A quick search found a data sheet here ( http://www.national.com/ds/LM/LM78L05.pdf )

While they are ESD sensitive devices, they tend to be rather robust so a little handling should not hurt them very much.

There are a number of things that these little guys dont like:
1: Input power and ground reversed. So watch your polarity when applying power.
2: Voltage on the output being driven higher than the input voltage. This typically only happends with some sort of inductive kick, but ...
3: Applying more than 35 Volts at the input. Some power supplies (especially older ones) may spike when turning on. Check your power supply with an o'scope to see if it spikes (DMMs don't read fast enough).

They can be bought here http://search.digikey.com/scripts/Dk...M78L05ACZNS-ND

[Ed Sparks]

Originally Posted by Daniel_LaFleur

Looking at your picture, the part is made by National Semiconductor (thats the funky looking 'N' as the first letter) .

A quick search found a data sheet here ( http://www.national.com/ds/LM/LM78L05.pdf )

While they are ESD sensitive devices, they tend to be rather robust so a little handling should not hurt them very much.

There are a number of things that these little guys dont like:
1: Input power and ground reversed. So watch your polarity when applying power.
2: Voltage on the output being driven higher than the input voltage. This typically only happends with some sort of inductive kick, but ...
3: Applying more than 35 Volts at the input. Some power supplies (especially older ones) may spike when turning on. Check your power supply with an o'scope to see if it spikes (DMMs don't read fast enough).

They can be bought here http://search.digikey.com/scripts/Dk...M78L05ACZNS-ND

Hmmm.....

Says in the data sheet that these regulators have short circuit and thermal protection built in. In other words, given that the power source is within spec, you should not be able to destroy them (no matter what the load). Maybe some were accidently powered up with reverse polarity at some point. I'm leaning toward the explanations in Daniel's list.