AV switch light not working

[Molina00]

I got everything wired up and it all worked perfectly during several tests but I fired it up tonight and the light on the AV switch didn't illuminate. The light was a little bit dim but it still worked, up until now. I have included my wiring and diagram in case there is a problem with it somewhere. Sorry if the wires are kind of tangled. I didn't realize it until I had finished wiring, and can't fix it without undoing the connections. Also is it normal for the resistor going to the LED to be really hot while it's running?

http://img.photobucket.com/albums/v233/molina00/IMAG0149.jpg

http://img.photobucket.com/albums/v233/molina00/sketch1428807158151.png

[Silver Serpent]

I don't see any issues with the wiring, and your diagram looks correct. Have you tried charging the battery?

[DarthMace]

Correct me if I'm wrong, but I believe the dynaohm resistor has a very low wattage rating, and is usually used to cut current/voltage from 3.3v pads on Plector boards. If you are using a red AV switch, the problem may be that the ~2V that the resistor has to dissipate from the battery caused a resistor burn-out...or a LED burn-out if the resistor failed.
I'm just guessing here, so take this with a grain of salt.

[Silver Serpent]

According to the spec sheet on the DynaOhm, the 20mA version supports a 30v drop. They're designed to work well at much higher voltages than we deal with, so I don't think the 3.7v from his battery pack is the issue.

The resistor going to the main LED is going to get hot when the saber is on. Standard resistors dissipate the extra current as heat. If you can still touch it without burning yourself, it's probably not too hot.

[Molina00]

I don't see any issues with the wiring, and your diagram looks correct. Have you tried charging the battery?

Yes, sir. That was on a full charge. Maybe the switch just had a bad LED? It worked fine up until last night when it stopped coming on at all. Is it normal for the LED to be somewhat dim? When I first fired it up it was bright but dimmed as I left it running.


Correct me if I'm wrong, but I believe the dynaohm resistor has a very low wattage rating, and is usually used to cut current/voltage from 3.3v pads on Plector boards. If you are using a red AV switch, the problem may be that the ~2V that the resistor has to dissipate from the battery caused a resistor burn-out...or a LED burn-out if the resistor failed.
I'm just guessing here, so take this with a grain of salt.

I wondered about that myself, maybe I had blown out the LED in the switch, but from what Silver Serpent says it sounds like the resistor should have handled the voltage. So I guess it's just a mystery. I will be wiring another setup with a green AV switch so I'll see if I get the same result with that one.



The resistor going to the main LED is going to get hot when the saber is on. Standard resistors dissipate the extra current as heat. If you can still touch it without burning yourself, it's probably not too hot.

I thought that was probably the case but wanted to ask anyway. The resistor was getting pretty hot, wouldn't want to touch it for more than a second. I will assume it's fine though unless I find out differently.

Thanks for the input, both of you.

[Silver Serpent]

It's possible that either the switch LED was bad, or the DynaOhm was defective. Neither are particularly likely, but I don't see any other probable causes.

[Molina00]

It's possible that either the switch LED was bad, or the DynaOhm was defective. Neither are particularly likely, but I don't see any other probable causes.

Okay, thanks. I guess I'll order another switch and resistor and see what happens.
One more quick question. The resistors all come with attached wires longer than I need them to be. It doesn't hurt anything to cut them down to a shorter length does it?

[Silver Serpent]

Not a bit. You should really shorten the wires for your setup so you don't have as much to cram into your hilt. Long wires are fine for testing, but they just get in the way when you're trying to close up the saber.

[Molina00]

Not a bit. You should really shorten the wires for your setup so you don't have as much to cram into your hilt. Long wires are fine for testing, but they just get in the way when you're trying to close up the saber.

Thanks again. Your input is most appreciated. :cool:

[Lobezno]

Have you tried the LED with the multimeter? I promise you it won't burn... That way you can check if the LED works...

[Molina00]

Have you tried the LED with the multimeter? I promise you it won't burn... That way you can check if the LED works...

I didn't think of that. I'll give it a try when I get home.

[Lobezno]

Hey, you tried that LED? Is it fried or it's OK?

[Molina00]

I wasn't sure how to check it since the posts are covered in heat shrink but it just occurred to me I could strip the wire and try that.

I'm not really sure what's going on with these red switches. I ordered a second one and, while it works, it dims and flickers and goes off and comes back on. It's weird but I'm just going to go with it. The green one I wired in another setup works just fine, it stays on nice and bright.

[Lobezno]

The green one behaviour is the desired... The red one is really weird.

Try the red getting the power from the 3.3v accent pad in the nano B, and let the LED wire straight to the LED. I did that in my CF 6.5 and 0 problems.

[Molina00]

I already have everything installed in my saber so I'm just going to go with it as is. The sound and LED work properly so that is the important thing. I will keep that in mind for any future builds though. Thanks for the suggestion.

[Bark]

While resistors can go on facing either direction, the DynaOhm requires more. It needs to be on the Positive(+) side of the LED. You're diagram shows this, good. Also, the DynaOhm's posts are specific too. The battery(+) must connect to the IN post on the DynaOhm, and the LED(+) must connect to the OUT post on the DynaOhm.

Since no one else has asked yet and you didn't specify, did you put the DynaOhm on correctly with the IN post going to the battery and the OUT post going to the LED?

[Molina00]

While resistors can go on facing either direction, the DynaOhm requires more. It needs to be on the Positive(+) side of the LED. You're diagram shows this, good. Also, the DynaOhm's posts are specific too. The battery(+) must connect to the IN post on the DynaOhm, and the LED(+) must connect to the OUT post on the DynaOhm.

Since no one else has asked yet and you didn't specify, did you put the DynaOhm on correctly with the IN post going to the battery and the OUT post going to the LED?

I didn't know that. I'll have to pull the switch out and check when I get home. Thanks for the suggestion. It would be nice if it could be something that simple.

[MedicineMan]

why not run the LED from the switch to the accent LED pad?

[Forgetful Jedi Knight]

why not run the LED from the switch to the accent LED pad?

He probably wants it to come on when the LED does.

[Molina00]

While resistors can go on facing either direction, the DynaOhm requires more. It needs to be on the Positive(+) side of the LED. You're diagram shows this, good. Also, the DynaOhm's posts are specific too. The battery(+) must connect to the IN post on the DynaOhm, and the LED(+) must connect to the OUT post on the DynaOhm.

Since no one else has asked yet and you didn't specify, did you put the DynaOhm on correctly with the IN post going to the battery and the OUT post going to the LED?

Thank you so much for that information. Turns out I did have the resistor backwards and the AV switch is now working normally. If this site had reputation points I would give you some. Since it doesn't, I'll just have to say thanks. :D

[Lobezno]

Awesome, mate! Glad to hear, fixed!

[Molina00]

Thanks. I'm going to guess the first switch I tried is fine too as I also had the resistor backwards on that one. So I have an extra red switch and resistor for future upgrades. :cool:

[Bark]

Thank you so much for that information. Turns out I did have the resistor backwards and the AV switch is now working normally. If this site had reputation points I would give you some. Since it doesn't, I'll just have to say thanks. :D

I'll take the thanks. I'm glad it was an easy fix. The more you know... :)