Ok, what did I do wrong? (Exploding Driver) (Probable false alarm)

[LLCoolBeans]

My knowledge of electronics and electricity in general is pretty basic, so please forgive my ignorance.

Modding the dome light of my Subaru. I machined a beautiful brass heat sink that fits perfectly into the housing and am planning to use two SSC P4s in series.

Before assembling everything and attaching emitters to the heat sink, I decided to do a quick test to make sure everything was going to work. Wired up a driver (luxdrive 350ma buck puck) with an expendable emitter on a test heat sink.

Hooked it up, flipped the switch on, and the driver immediately EXPLODES.

I may have gotten the polarity reversed as there are no black or red wires or maybe there is just too much current on that circuit for the driver to handle?

How do I measure the current on that circuit? I tried using my multimeter with the red lead on the current side, but all that does is blow the fuse.

If there is too much current, how do I limit it? A resistor?

Thanks

 

[Mr Happy]

Re: Ok, what did I do wrong? (Exploding Driver)

My knowledge of electronics and electricity in general is pretty basic, so please forgive my ignorance.

We might forgive you, but BuckPucks and multimeters are not that forgiving.

Hooked it up, flipped the switch on, and the driver immediately EXPLODES.

Ah, you made a mistake and you will learn from it.

I may have gotten the polarity reversed as there are no black or red wires or maybe there is just too much current on that circuit for the driver to handle?

"Maybe" getting the polarity reversed is not an option. You must make sure you have every connection correctly made, no mistakes.

How do I measure the current on that circuit? I tried using my multimeter with the red lead on the current side, but all that does is blow the fuse.

If there is too much current, how do I limit it? A resistor?

You are using the wrong word "current" here, and maybe that is part of your problem. You need to consider voltage mainly, and polarity, and connecting the right wires to the right terminals.

Which exact model BuckPuck did you use? Did you use the optional wiring harness with color coded wires? What supply did you try to power it from when you did the test?

 

[ambientmind]

Re: Ok, what did I do wrong? (Exploding Driver)

did you electronically isolate the leds from the heatsink? the slug on the led is tied in with the positive with seouls so if your heatsink was grounded, that might explain why things blew up. But check, double check, and triple check your connections are correct before applying power. maybe post some pics of your setup so we can help you further. its all just part of learning...

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

You are using the wrong word "current" here, and maybe that is part of your problem. You need to consider voltage mainly, and polarity, and connecting the right wires to the right terminals.

Voltage shouldn't be an issue, I tested that, multimeter reads about 12.5 volts coming from the socket, buck puck should handle that no problem.

Ah, you made a mistake and you will learn from it.

Yup, unfortunately this is how I tend to do most of my learning. The hard way. That said, I generally learn pretty fast this way.

Which exact model BuckPuck did you use? Did you use the optional wiring harness with color coded wires? What supply did you try to power it from when you did the test?

This is the wired buck puck, the one I used to test was the 350ma "E" model (E model uses a pot for dimming).

I've tested these many times before in my shop with a variable PS and built lights with them in the past, never had a problem before. This is the first time I've used one in an automotive setting.

The "power supply" I used when the driver exploded was a Subaru Outback.

When I say the polarity is not immediately apparent, I mean the leads in the dome light socket, the buck puck is color coded and labeled so that there can be no confusion.

So, maybe all I did was reverse the polarity? I want to make sure that's the issue, before I repeat this little experiment, buck pucks are not cheap.

Thanks for the quick reply Mr. Happy.

P.S. I enjoyed reading your books as a small child.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

did you electronically isolate the leds from the heatsink? the slug on the led is tied in with the positive with seouls so if your heatsink was grounded, that might explain why things blew up.

I am 100% certain, this is not the issue.

But check, double check, and triple check your connections are correct before applying power. maybe post some pics of your setup so we can help you further. its all just part of learning...

I think I must have reversed the polarity of the Vin leads on the buck puck. Everything else was fine and I tested with my variable PS at the same voltage, before bringing everything out to the car to test.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

So, if I use my multimeter to test and it reads negative voltage, that means I have + connected to - and - to +, or the other way around?

 

[Mr Happy]

Re: Ok, what did I do wrong? (Exploding Driver)

You can check the polarity of the wires in the car using the DMM on volts. It will show a minus sign in front of the voltage if the polarity is reversed. [Edit: That means if you have the red lead connected to minus and the black lead connected to plus, you will see a negative voltage.]

Since I can't see your setup, and you may be aware of this anyway, I will mention about the chassis of a car being grounded directly to one pole of the battery. It is therefore very important to make sure the right bits are isolated and insulated when working with automotive electrics to prevent a catastrophic short. This might not be a problem for you, but when you make mention of a "beautiful brass heat sink" it becomes a consideration.

Another point about the BuckPuck blowing up is to ask about fuses. It would not hurt to put a low value inline fuse in your supply wire -- you may be connecting to a circuit where the central fuse is shared by other circuits and has a relatively high value like 20 A. A small value inline fuse of about 1 A might save you from further explosions.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

Since I can't see your setup, and you may be aware of this anyway, I will mention about the chassis of a car being grounded directly to one pole of the battery. It is therefore very important to make sure the right bits are isolated and insulated when working with automotive electrics to prevent a catastrophic short. This might not be a problem for you, but when you make mention of a "beautiful brass heat sink" it becomes a consideration.

The new brass heat sink was not in the mix during the mishap. I used a scrap heat sink that I use specifically for testing, and yes everything was isolated and I have used this setup many times before.

Another point about the BuckPuck blowing up is to ask about fuses. It would not hurt to put a low value inline fuse in your supply wire -- you may be connecting to a circuit where the central fuse is shared by other circuits and has a relatively high value like 20 A. A small value inline fuse of about 1 A might save you from further explosions.

The only other devices on the circuit are the other interior lights. It uses a 15A fuse.

I like your inline fuse idea, I'll definitely do that before I test again. Maybe I'll even build a replaceable one into the housing.

Thanks for the help.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

Dang! Closest DC fuse to 1A that I have is a 5A. I don't suppose that's low enough, is it?

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

Ok, just verified for sure that I connected the input leads backwards.

So, I'm going to try again.

Just for the record: Buck Puck + Reverse polarity input + 13V =

EDIT: Just repeated the test with a new driver and correct polarity. Everything works fine. Tested on the bench, then in the car, no problems.

Positive lead is blue negative lead is white with a red stripe, go figure.

 

[VidPro]

Re: Ok, what did I do wrong? (Exploding Driver)

what you did wrong was to not buy 2 one to learn one to burn.
hey you had a 50-50 chance , thats good odds if you ask me.

i find that even a cheap bench power supply helps a LOT on checking stuff prior to connecting it to things where you dont have enough control.
with a bench power supply (that can control amps) you can drop the (supply) voltage and current to 0, then work your way up slowly.
by doing that even if you dont know the polarity, you can (most often) keep the current so low, that it doesnt destroy everything when its wrong.

so if your going to do a lot of this stuff, a cheap bench supply can save more dollers than it costs.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

what you did wrong was to not buy 2 one to learn one to burn.

I have several of these. I ended up using the 500ma version in the final product.

i find that even a cheap bench power supply helps a LOT on checking stuff prior to connecting it to things where you dont have enough control.
with a bench power supply (that can control amps) you can drop the (supply) voltage and current to 0, then work your way up slowly.
by doing that even if you dont know the polarity, you can (most often) keep the current so low, that it doesnt destroy everything when its wrong.

so if your going to do a lot of this stuff, a cheap bench supply can save more dollers than it costs.

I do have a bench power supply and I tested first with it. The problem was that I got the leads in the dome light socket mixed up.

 

[VidPro]

Re: Ok, what did I do wrong? (Exploding Driver)

see now that couldnt even happen 30 years ago, if you wanted power in a Car, you had one wire and the metal (ground) , never any doubt about which was which.
now you got plastic and 2 wires , nothing good can come of it

 

[VegasF6]

Re: Ok, what did I do wrong? (Exploding Driver)

How exploded is it? Pics

Does anyone know if the wired buck puck is encapsulated? Maybe you just poofed a diode.

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

How exploded is it? Pics

Does anyone know if the wired buck puck is encapsulated? Maybe you just poofed a diode.

It wasn't as impressive as it sounds. It made a pop, there was a flash and then a horrible stench. My hand was near it when it popped and I felt heat, not enough to burn, but almost.

It didn't explode into pieces but the epoxy is split on one side.

Not sure what you mean by encapsulated, but it's a PC board potted in epoxy.

 

[Mr Happy]

Re: Ok, what did I do wrong? (Exploding Driver)

Somewhat like the household mains, a car battery can for all practical purposes supply unlimited current. Where a bench power supply might stop at 5 amps or so, a car battery will just be warming up at 100 amps. That's more than enough to blow up circuit boards, wires, connectors, and anything else that happens to get in the way. So when working with car electrics it is doubly important to check all connections before applying power. As LLCoolBeans found, a 15 amp fuse might be enough to stop the wiring harness catching fire, but it is not enough to save a little electronic circuit from going pop...

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

AARG! Update and more problems.

Got a disturbing phone call from the wife today. She said that when she unlocked the car and opened the door this morning that there was a horrible smell.

I did not take into account that the remote door lock flashes the interior lights. It must be reversing the polarity or something else weird, when that happens.

Dang, why didn't i think to test what happens to the voltage in the dome light socket when you lock the doors?!

I won't know for sure until later this evening.

I have to assume the door lock reverses the freaking polarity, how do I set up some sort of reverse polarity protection?

Thanks

 

[VegasF6]

Re: Ok, what did I do wrong? (Exploding Driver)

Oh man you are having a terrible time with this. I haven't seen a case where polarity is reversed to the dome light, but cars now days do strange things. In my car for instance a lot of things controlled by the BCM are ground switched.

I am no electronics expert either, so I am sure you will get better suggestions following mine. But, for in the meantime, I am thinking you need a diode on the input which is what I was hoping what blew in the original disaster. Let's wait till someone else chimes in but I am thinking to be safe you might need to have a diode on both the positive and negative side. There will be some voltage drop, ~.7v for each diode.

Just to make sure we are on the same page, you are using buckpuck 3023-d-e-500?
http://www.ledsupply.com/03023-d-e-500.php

If not reverse polarity, be sure no shorts are taking place of course. And triple check your wiring. Are you using this as a simple on off? Does your car have a "theater style dimming light?" (the dome light fades off after ~30 seconds instead of a hard cut off)

I am not doubting your ability but maybe you could tell us exactly which color wires are hooked up to what?

 

[VidPro]

Re: Ok, what did I do wrong? (Exploding Driver)

bridge rectify the WHOLE thing , so polarity doesnt mater at all, some buck driver things HAD that in it, it wastes lots of voltage and power, but it made it fool proof.
and stuff in at least a resettable breaker while your at it, they make little TINY self resetable heat breakers that will click on and off, on and off, instead of hosing everything. and blade fuses for small cars, they are cheap and you can solder to the legs easily. or just use very small wire to connect, it will fuse itself, and burn up quikly dropping on the driver

but lets just hope that the stench of fried components , that lingers like dead fish in the hot sun was the only thing she smelled, and everything is peachy keno.

3amp bridge rectifyers at the radioshack are cheap, small and will fit in almost anything like this.
you just wire up the CAR side, on the "AC" and the buck driver with the correct polarity on the + and -.
a bridge is just a set of 4 diodes, that direct the power only one way.

and just in case i am wrong , test it on the bench , or get verification from some EE (electrical expert) on the forum here. but i am pretty sure that would fix it, even though they are designed for "AC" the same thing would always direct the power through the diodes in only one direction , even with the DC.

if the item you are making was "manufactured" and power wasting was not such a big deal, they would toss in the 4 cheap diodes into the product, so stuff like this didnt happen. because stuff like this DOES happen

AARG! Update and more problems.

Got a disturbing phone call from the wife today. She said that when she unlocked the car and opened the door this morning that there was a horrible smell.

I did not take into account that the remote door lock flashes the interior lights. It must be reversing the polarity or something else weird, when that happens.

Dang, why didn't i think to test what happens to the voltage in the dome light socket when you lock the doors?!

I won't know for sure until later this evening.

I have to assume the door lock reverses the freaking polarity, how do I set up some sort of reverse polarity protection?

Thanks

 

[LLCoolBeans]

Re: Ok, what did I do wrong? (Exploding Driver)

Oh man you are having a terrible time with this. I haven't seen a case where polarity is reversed to the dome light, but cars now days do strange things. In my car for instance a lot of things controlled by the BCM are ground switched.

I am no electronics expert either, so I am sure you will get better suggestions following mine. But, for in the meantime, I am thinking you need a diode on the input which is what I was hoping what blew in the original disaster. Let's wait till someone else chimes in but I am thinking to be safe you might need to have a diode on both the positive and negative side. There will be some voltage drop, ~.7v for each diode.

Just to make sure we are on the same page, you are using buckpuck 3023-d-e-500?
http://www.ledsupply.com/03023-d-e-500.php

If not reverse polarity, be sure no shorts are taking place of course. And triple check your wiring. Are you using this as a simple on off? Does your car have a "theater style dimming light?" (the dome light fades off after ~30 seconds instead of a hard cut off)

I am not doubting your ability but maybe you could tell us exactly which color wires are hooked up to what?

I'll have to use my multimeter to see what is going on when the door lock is activated.

I triple checked all my connections before installing, nothing is grounding out. All solder connections are shrink wrapped except for the ones on the star boards, but those aren't near anything so I can't imagine anything is shorting.

Wife had no problem with it, until she tried locking the door. Then .

I won't know for sure until I can test it, but common sense tells me the socket must be reversing the polarity when it blinks the interior lights.

If the diodes reduce the voltage coming from the socket, that will be no problem. Buck Puck only needs something like 5.25V to operate, but will accept up to 30 or something.

No, dome light does not do the theater dimming.

Wired Buck Puck 500ma "E" model using a low power Pot for dimming. 2xSSC P4 S2 bin emitters on star boards wired in series.

I'm positive all leads are now properly attached.

Thanks

EDIT: It works great BTW, this is a major improvement. Assuming you don't lock the doors.