Improved dash lighting 300E, 1986 - PeachParts Mercedes-Benz Forum

300holst · #1 12-03-2006, 08:35 PM

I finally couldn't take the dim dash lighting in my '86 300e. I could only see the top half of the speedometer and gas guage. This was even after installing new 3W bilbs and cleaning the light prism faces.

Using an idea I got either from this forum or from the Brickboard (can't remember which), I removed all the original plastic prisms and installed LEDs. The results are really great. Now I can see even the numbers on the trip odometer. The posted photo below shows the new lighting fairly well although the lighting is actually even better than you see in the photo. Upon examining the plastic prisms, I could see that the 'capture area' where light from the bulb enters the prism is quite small. The efficiency of this system has to be low.

If there is interest, I'll go into more detail with pictures. That is assuming I learn how to attach pictures.

Briefly, I pulled the cluster out, used a Dremel to grind out the plastic welds holding the two prism covers, removed the old yellowed prisms, painted flat white around the slots where the prisms had reflected light back to the guages, and mounted two, white, LEDs in each slot. The LEDs are powered by a 9v regulated supply which draws 12v from the dash light dimmer supply. I also painted the guage needles with a fluorescent orange model paint which I bought at a toy store. The total cost was under $5.00.

Battlecat714 · #2 12-03-2006, 08:53 PM

Quote:

Originally Posted by 300holst

If there is interest, I'll go into more detail with pictures. That is assuming I learn how to attach pictures.

Please do, I have a burnt bulb in the cluster so I might as well go all the way in replacing it.

dkveuro · #3 12-03-2006, 08:56 PM

Wow...conciderable improvement....say...where do I get those new 3w 'bilbs' from ?

.

pwogaman · #4 12-03-2006, 09:34 PM

Impressive! Please show us the pictures. Does the dimmer work with the LED's?

cjlipps · #5 12-03-2006, 11:21 PM

Hey, that looks cool but definitely not for me. I always run with my dash lights as low as I can get them and still read the gauges at a glance. Learned that trick while flying, the bright dash lights inhibit your vision outside.

300holst · #6 12-04-2006, 12:29 PM

Quote:

Originally Posted by dkveuro

Wow...conciderable improvement....say...where do I get those new 3w 'bilbs' from ?

.

I wasn't clear enough. The improved lighting is from replacing the original 3W bulbs with an LED lighting system. The original bulbs are 3W and sometimes these get darkened with age. New bulbs help but still don't really give enough light. You can put in 5W bulbs but these are much hotter and will eventually melt or warp the plastic near the bulbs. I used LEDs because they put out practically no heat.

300holst · #7 12-04-2006, 12:41 PM

Quote:

Originally Posted by pwogaman

Impressive! Please show us the pictures. Does the dimmer work with the LED's?

No, the dimmer does not control the LEDs. I was satisfied with the lighting just as it is. However, if your night vision is better than mine or possibly on a long night drive (which I avoid as I get more senior), you might wan't to be able to dim the dash lights. I have thoughts on how to do this but it would require more electronics.

An LED is essentially an ON-OFF device. You can control the light a small amount by controlling the current through the LED but this isn"t really enough control. The LED output can be controlled by turning it on and off rapidly and varying the duty cycle, i.e. the time the LED is pulsed compared to the time it is off. Much like setting the idle mixture control in my MB. If this is done fast enough, the eye doesn't see any flickering of the light.

I'm still waiting to see the interest in posting the pictures showing how I did this. We'll see.

300holst · #8 12-04-2006, 12:48 PM

Quote:

Originally Posted by cjlipps

Hey, that looks cool but definitely not for me. I always run with my dash lights as low as I can get them and still read the gauges at a glance. Learned that trick while flying, the bright dash lights inhibit your vision outside.

You are absolutely right. I seem to remember that aircraft use red lights in their instrument panels in order to save the blue-green photo receptors in the eye for detecting lights outside the cockpit. Is this right?

I tried using red LEDs but the visibility of the guages wasn't good. Same with blue lights which were 'bloddy awful' as the Brits might say.

Most of my night driving is in the city where you get bright lights all around and the dash needs to be well lighted to compete.

As you can see in my answer to the previous post, there may be a way to include a dimmer control feature. Perhaps I'll try that although I'm a bit tired of pulling out the cluster for now.

cjlipps · #9 12-04-2006, 01:48 PM

The panel lights are typically white but there can also be a red "dome" light that can be brought into use to read charts, etc. Also a red lens flashlight is highly recommended.
Good point about the ambient light. Most, if not all of my night driving is a 40 mile commute through rural NW Oklahoma on two-lane roads. I can definitely see where brighter dash lights would enhance visibility in city night-driving.
Another thought, and I have absolutely no facts to back this, but a guy might be careful about switching the led off and on rapidly. Even though the flashing isn't consciously detectable, it might be like the subliminal advertising in days gone by and it seems I read something somewhere about flashing lights inducing nausea. And for another aviation reference, flying with the propeller arc passing over the sun is known to cause nausea from the rapid flashing even though it's virtually undetectable (2 blade prop at 2400 rpm is 80 flashes per second). It's been quite a while since ground school and training so I might be delusional on this. Anybody else?

Battlecat714 · #10 12-04-2006, 09:51 PM

hey how long did the whole mod take?

neanderthal · #11 12-05-2006, 01:40 AM

im intrested in this as well, but only if i still have the capacity to dim the lights when needed.

i generally turn off the lights as much as possible when driving at night, especially when im driving long distances. my eyes get "tired" from the glare. ill even put on sunglasses to reduce glare from oncoming traffic.

SootyPast · #12 12-05-2006, 09:42 AM

I would be very interested in detailed photos/part #'s etc. I was going to pull the cluster out of one of my 126's and think I will give it a shot. The brighter lights have never bothered me. Thanks for the post. PM me if you would prefer. Steve

300holst · #13 12-06-2006, 10:50 AM

Quote:

Originally Posted by Battlecat714

hey how long did the whole mod take?

It would be hard to estimate how long this job might take. I experimented around with different lights, etc. I also was working on modifying a Volvo 240 cluster too.

Not counting the time to R&R the cluster, and if you had all parts on hand, I'd think a person could get this done in an afternoon. I'm assuming you know how to solder a bit.

300holst · #14 12-06-2006, 10:54 AM

Quote:

Originally Posted by SootyPast

I would be very interested in detailed photos/part #'s etc. I was going to pull the cluster out of one of my 126's and think I will give it a shot. The brighter lights have never bothered me. Thanks for the post. PM me if you would prefer. Steve

There seems to be some interest in this dash modification so I'll post a "how to do it" thread as soon as I can. Got to get going on Christmas shopping or I'll find it's too late. (Typical male)