The only place I ever put LEDs in my 300D were the two that light up the cluster at night. It might have been because of a problem with the rheostat, but the old incandescents just didn't have enough same candle power.

It was a recommendation by Chad300DT. I must say, it was the best mod that I ever did.

My ultimate goal was the use clear glow in the dark nail polish on the cluster and then put in a blacklight LED to make it all glow. I never did it mostly because of my painting inabilities.

Now that would have looked cool!

Well cost for one, and also all the stuff required to get them to work in systems designed around incandescent bulbs as has been touched upon already in this thread is another. Want an LED in the W126/124/201 reading light? The socket is wired in reverse polarity. Have to disassemble the LED and resolder the leads. Whether the cost and effort is worth it is up to the user, but the incandescents do the job just fine cheaper with no thought involved.



Many unrestored cars from the '50s on up have original bulbs in the idiot lights. I highly doubt the current slew of Chinese LED bulbs will last that long.

Hey would you mind posting a picture of the paint you used? I know you mentioned the brand and color but I'm seeing a few results when I Google "Testors Tangerine Orange."

Your needles came out excellent and just the right color. I've seen many people use the wrong color and I'd like for mine to look exactly like yours. Thanks

- Sonny

I can send it to you. PM me

Alternator Charging
 

The 3W bulb for the battery idiot light provides DC excitation (12V is provided to the alternator's field windings - this excites, or "jump-starts" the alternator). Without it, the alternator will not charge.

I changed the two instrument lighting bulbs on mine to LED's but didn't go any further. I like it. The light is "whiter" and the bulbs work with the rheostat. The paint was Testors Fluorescent Red. It all works. I also got mad at Mercedes for making the combo gauge all metric on a U.S. ONLY car so I got one of their earlier gauges in SAE, removed the decorative silver center button and stuck a black disc in its place to match the rest of the gauges. Sorry but between a reading of 2 bar vs 30 psi, 2 bar sucks.

Thanks, Wusha, for sending me the supplies to repaint my needles.

Before:

https://i.imgur.com/aabkcXLl.jpg

After:
https://i.imgur.com/y6zlInZl.jpg


For the record anyone researching about painting their needles, Testors "Gloss Tangerine" is the way to go for older Mercedes. Make sure to thin it a bit as not to leave brush strokes.

Also, save yourself the extra step and extra product there is no need to thin. That's not how this or any ready to use paint works.

FOund this on a different car forum, Not a merc, but looks like it might be a solution... The wiring colors are incorrect so dont go by them.

"
Start with the "normal" warning lamp configuration where a white wire goes from the ignition switch, to the lamp, out the lamp via a brown/yellow wire and finally off to the alternator. Replace the warning lamp with a 40 Ohm power resistor (something rated for at least 1 Watt). NOW get your LED lamp assembly. A plain LED will need a "dropping resistor", typically 1000 Ohms. A pre-configured LED warning lamp will already have this resistor inside. Take your LED lamp (or LED with dropping resistor) and wire it in PARALLEL with the 40 Ohm power resistor. Pay attention to the polarity or the LED will not light. With the LED wired in parallel to the 40 Watt resistor... the LED will turn on and off just like a normal incandescent light. However, the current required to power the alternator field coils on startup will pass through the 40 Watt resistor."

Anyways, I'm attempting this myself, I'll report if I have any luck.