AV switch light not working

**Molina00** · 04-14-2015, 08:47 PM

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?

**Silver Serpent** · 04-15-2015, 07:17 AM

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

**DarthMace** · 04-15-2015, 07:25 AM

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** · 04-15-2015, 07:43 AM

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** · 04-15-2015, 08:12 AM

Originally Posted by Silver Serpent

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.

Originally Posted by 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.

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.

Originally Posted by Silver Serpent

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** · 04-15-2015, 08:19 AM

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** · 04-15-2015, 08:44 AM

Originally Posted by 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.

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** · 04-15-2015, 08:57 AM

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** · 04-15-2015, 08:59 AM

Originally Posted by 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.

Thanks again. Your input is most appreciated.