PeachParts Mercedes-Benz Forum - View Single Post - 82 300TD I want my window switches to light up!!!!

nibiru · #14 10-16-2003, 05:00 PM

TomJ:

Nice work - I understand the quest for answers.

I applied the 9 volt to the post outside bottom of switch case

I figured that this was the positive current line to the Anode + because there is a band of copper running from post ( short connection of LED- non resistor) to other LED on Passangers switch.

But yes as you say - power should go thru the resistor first

But>>>>.......... when I hooked up a 4.5 volt connect I put the + to the non resistor and the neg to the resistor and it lit up - so I though it was the way - due to LED's are completely polorized - so if the power travels the wrong way they dont light up

So I quess I have to bone up on the LED thing in the Benz applique. N

Now - I have to replace the LED's cause I wanted to test with a 9 volt.

Wait a MO.... I just tried the same pattern again
with a 4.5 volt I placed positive probe to the LED - Drivers switch directly to the short side without resistor and Neg ( - ) to the side with the resistor and it works. So perhaps whoever tried to fix it - if in fact they were tried to fix soldered them wrong or I do not understand the circuit

Tell me what you think?

I agree with you on the RADIO SHack- they dont have great LED's- I hear their best one have to be ordered on line or from catalog ( You can do this at the store and pay 2.50$ to ship directly to you)

I ordered a bunch or LED's for dash and fixtures because over the years I cant tell you how many 2721 bulbs I have had to replace. P I T A to pull a dash 2-3 times a year

Even ordered these really cool 12 V wedge but I have to return them cause polarity is on same side- must be for other than automotive

i am wondering if I can just wire 12 V LED's in place of these little 2.75mm LED ( Mercedes choice ) and do away with resistor. probably had to do thaht way when in the early 80's LED were so new no one saw a reason to have 12 V LED's

Gotta get a Digi Cam so I can post my finding as well

I am thinking Blue to replace the orange Hmmmmmmmmm.....

Peace