Previous Thread
Next Thread
New Reply
Print Thread
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 12:30am - #269139 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Electrical Experts...

Ok, I think I soldered in my LED's in backwards, and before I go in and reverse the polarity, answer me this question...

In the picture below, is a crude drawing of the "T" symbol on the back of a surface mount light emitting diode. I'm having some trouble intreperting it.
1870217179-ssss.jpg

Aqua Teen Hunger Force...number one in the hood, G
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 12:56am - #269140 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Bastards...

Aqua Teen Hunger Force...number one in the hood, G
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 12:58am - #269141 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Sons a bitches...

Aqua Teen Hunger Force...number one in the hood, G
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 1:31am - #269142 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
frown

Aqua Teen Hunger Force...number one in the hood, G
Joined: Jul 2004
Posts: 23
brianhaman
Member
brianhaman Sep 8, 1:57pm - #269143 
2003 White Toyota Celica
Member
2003 Toyota Celica

Joined: Jul 2004
Posts: 23
Florida
If you have access to a volt meter you can use the diode checker function to test the LED for polarity.
Joined: Sep 2004
Posts: 126
Teknikal
Member
Teknikal Sep 8, 2:13pm - #269144 
2000 Silver Toyota Celica
Member
2000 Toyota Celica

Joined: Sep 2004
Posts: 126
Louisville, KY
Well generally your Anode is your "longer" terminal of your LED also the positive.

Also from your drawing I would assume that it is anode->cathode because a typical diode symbol is --|>|--
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 5:03pm - #269145 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Originally Posted by Teknikal
Well generally your Anode is your "longer" terminal of your LED also the positive.

Also from your drawing I would assume that it is anode->cathode because a typical diode symbol is --|>|--
It's a surface mount LED meaning that it doesn't have prongs as terminals.


And yeah, I did do a test with a voltmeter, and found out that I did have them on backwards.

But I still have a problem...


I changed a few around to the correct way that they should be mounted, and went back and tested it in my car expecting to see only those few light up.

Wrong. None of them are lighting up still.


I wonder if it's because they are all along the same circuit, and they have to all have the same polarity, or perhaps it's because at the bottom of the board, I'm missing two LED's due to the fact that on the board on one side, one of the mounting pads is missing, so I just left out the LED on that side, along with the LED on the other side so it would look like it's supposed to be that way.


Anyone know if this is perhaps why none of them are lighting up? Because two LEDs are missing?

Aqua Teen Hunger Force...number one in the hood, G
Joined: Jun 2004
Posts: 22
s71ck
Member
s71ck Sep 8, 8:22pm - #269146 
2000 White Toyota Celica GT
Member
2000 Toyota Celica GT

Joined: Jun 2004
Posts: 22
CO, USA
Yes the LED's are connected in series of 2 or 3 so if one is reverse polarized the other 2 or 3 on that circuit wont work. So what i did to test this was only unsolder 1 LED and replace it with 1 new blue LED, if it didnt work i had it in backwards. I just found this out last night because i was doing the same thing. What i found to be the easiest is to look at the front of the surface mount LED and make sure the little square in the clear part, called the die, is pointing to the bottom of the gauge circuit board. This is of course if you are using blue LEDs, if they are red however the die should be at the top.

PS: This is what part of the alphabet would look like if Q and R were eliminated.
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 8, 8:58pm - #269147 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Originally Posted by s71ck
Yes the LED's are connected in series of 2 or 3 so if one is reverse polarized the other 2 or 3 on that circuit wont work. So what i did to test this was only unsolder 1 LED and replace it with 1 new blue LED, if it didnt work i had it in backwards. I just found this out last night because i was doing the same thing. What i found to be the easiest is to look at the front of the surface mount LED and make sure the little square in the clear part, called the die, is pointing to the bottom of the gauge circuit board. This is of course if you are using blue LEDs, if they are red however the die should be at the top.
Gotcha, thanks.


Even when I reversed the direction on some of the LEDs, they still won't light up. Could it be the fact that I'm missing two LED's on the very bottom of the board?

I believe those two light up the hole in the tape deck.

Aqua Teen Hunger Force...number one in the hood, G
Joined: Jun 2004
Posts: 22
s71ck
Member
s71ck Sep 8, 10:38pm - #269148 
2000 White Toyota Celica GT
Member
2000 Toyota Celica GT

Joined: Jun 2004
Posts: 22
CO, USA
If the LED's weren't there from the factory, dont add extra ones, but if you de-soldered some and didn't re-solder in a new LED it would be the same as having one reverse polarized, the rest of the LED's in that series wont turn on.

PS: This is what part of the alphabet would look like if Q and R were eliminated.
Joined: Sep 2003
Posts: 3,077
slidr
Specialist
slidr Sep 9, 12:25am - #269149 

Specialist
2000 Toyota Celica

Joined: Sep 2003
Posts: 3,077
Saint Louis, MO
Originally Posted by s71ck
If the LED's weren't there from the factory, dont add extra ones, but if you de-soldered some and didn't re-solder in a new LED it would be the same as having one reverse polarized, the rest of the LED's in that series wont turn on.
There were two LEDs there from the factory. The reason I didn't put them in is because I damaged one of the mounting pads, and I left the other one out because it was coupled with the other one.


And none of the LEDs light up, so I guess this is near the source of the power, and I broke up the circuit?

Aqua Teen Hunger Force...number one in the hood, G
Joined: Jul 2004
Posts: 1,003
Sancho
SD Syndicate
Sancho Sep 9, 5:13am - #269150 

SD Syndicate
2004 Toyota Celica GT

Joined: Jul 2004
Posts: 1,003
San Diego, CA
Like I said in another post, theres many pathways in the circuit they could go. I'll assume that all the LEDs are on the same pathway.

Simple circuits, rule of thumb is if you have an open cicuit, nothing will happen. If there were LEDs in the two open ones, you should replace those or replace them with equally impendent resistors (keep the current the same). Make sure they are all polarized and check you solder connections. It took me a long time to realize that I needed flux with the solder I purchased.

If anything else, you could have burned one of the LEDs out. They're strong buggers, but it happens sometimes. idunnoGood luck and keep us informed.

[Linked Image]
2004 Toyota Celica GT
***Blue Batmobile sponsored vehicle***

Join the conversation - Register now or Sign in to add your comment


Moderated by  isaac 

Customize Your Toyota CelicaPrivacy Policy · About · Contact
CelicaHobby.com is an independent Toyota Celica enthusiast website. CelicaHobby.com is not sponsored by or affiliated with Toyota Motor Sales, USA, Inc. in any way. The Toyota and Celica names and logos are trademarks owned by Toyota Motor Sales, USA, Inc.
© CelicaHobby.com, 2001-2016