Light sockets and lights for VDO gauges - now LED instrument bulbs

[camron at worldaccessnet.com (Camron D. Crouse)]

Jim Jarrett wrote:

>On 7/22/05 9:35 AM, "Don Walter" <dswalterwi@gmail.com> wrote:
>
>  
>
>>I looked in Etka and they are:
>>437 919 039 for the socket
>>N 017 751 2 for the bulbs which are the standard dash bulbs incidentally.
>>Thanks for eveyones help. and those who suggested the dealer. who would
>>have thought.
>>    
>>
>
>Did you actually get some at the dealer, that worked?
>
>On a related note, didn't someone replace the backlighting for the dash
>cluster with LEDs?  Anyone got details on that procedure?
>
>/===============================================================\
>| Jim Jarrett,McFarland, WI      '94 Passat GLX                 |
>| mailto:jarrett@rpa.net         '86 Scirocco                   |
>|                                '81 Rabbit Convertible 16v     |
>|    Any problem can be solved with the proper application of   |
>|   Force, Heat, Chemicals, or Money.                           |
>\===============================================================/
>
>  
>

I have done the LED instrument cluster mod.  I got my LEDs from 
www.superbrightleds.com, lots of cool  stuff, including hard-to-find 
fixtures that actually fit out cars.  Prices are great, too.

Unfortunately, there are a few tricks to replacing instrument cluster 
the bulbs with LEDs, especially if you wish to change the color of 
illumination (half the point of doing the mod in the first place, no?)

1.  "T 1 1/2 (#73/74) miniature LED bulb installed in a twist-lock 
socket base"  These are the type I originally purchased.  It should be 
noted, that they don't quite "twist-lock" into place. Seems the LED 
socket base isn't exactly the same design as the Osram OEM bulbs. When 
they are installed into the cluster, watch the contacts on the LED base 
to verify they are connecting the contacts on the circuit board.  I 
found that if I turned the bulbs all the way to "lock", they ceased to 
connect on the circuit board.  Un-twist 1/8 turn or so... then they 
should make good contact, and be nice and snug in the cluster. 

2. LED Bulb polarity. - The bulbs need to be oriented properly in the 
cluster.  If the contacts are 180 degrees off, they will not 
illuminate.  Might take a couple tries to get all three bulbs to light 
up!  Hint - do this at night or in a darkened garage... otherwise is is 
impossible to see if they are lit up or not.

3. The LED bulbs with bases that I received have a convex (rounded) lens 
- the light is basically projected out the end of the bulb in a fairly 
narrow beam.  This is problematic, particularly with the digital clock 
bulb.  Since the OEM bulbs' filaments causes the light to be emitted 
from the bulb in all directions,  there is a nice, even source of light. 
When putting the LEDs in, they require substantial diffusion.  I used 
the Patrick's ATS "Change Your Instrument Cluster Illumination Color" 
Tech Note as a guide to take apart my instrument cluster to replace the 
OEM green diffusers.
<http://www.vintagewatercooleds.com/tech/Techtips/ATStechnotes/clusterlights/clusterlights.htm>
 Make a template of the original diffuser on a white frosted sheet of 
drafting mylar, found at a graphic arts supply shop.  Cut it with a 
nice, sharp X-Acto.  Paint any "light chambers" a nice bright silver to 
help reflect stray light onto your instruments.

4. superbrightleds.com now sells a concave-end, baseless LED cluster 
bulb.  Its beam is quite a bit wider, but still does not really emit 
from the sides very much.  It may be an improvement, though, when added 
with all the other aids.  However, it too is tricky to fit to the 
cluster. . I don't know if this bulb now also comes in a twist-lock 
base... I recommend sending them an email to find out  If not, for best 
results (if you are willing to put out a few extra bucks) order one set 
(3 bulbs) of  the twist-lock convex . Order an additional set of 3 
baseless, concave instrument LEDs in the color of  your choice ( I used 
blue).  Now, carefully remove the glass bulbs from your old Osram 
twist-lock bases.  All that is left is the plastic holder; the metal 
contacts are soldered to the glass bulbs, so they are of no use.  Now 
carefully remove the convex LED from their twist-lock bases.  There are 
two copper contacts in each twist-lock... carefully recover each pair, 
and then install them into the old Osram bases.  Now, place your new 
baseless concave LED bulb into this old Osram base and, Voila!  Now you 
have LED performance in an OEM true twist-lock base.

5. Even with the diffusion, the silver paint, etc., the output of a dark 
colored LED (such as my blue) onto black-face gauge may still be too 
low, so now is the perfect time to convert to white-face gauges.

Jeez, I forgot how much work it really was!

Is it worth it?  Well, once you are happy with your setup and your 
color, with the long life of LEDs you will likely never have to replace 
one of those damn bulbs again!

- Camron from Vancouver, WA USA
   '86.5 Black 16V 2.0L


*****************
 From the archives:

8/12/2004 11:02 PM

Instrument Cluster Lamps - Blue Twist Lock Single-LED T1 1/2 (#73/74) 
(these are tricky to make practical. First of all, the Twist Lock is a 
different design than the stock OSRAM  unit, so these will install, but 
the fit won't be as secure. If you are changing the color of your 
instrument cluster illumination, you'll want to remove the stock green 
color filter/diffuser and replace with white frosted drafting mylar...if 
you don't use a diffuser, then at night your instruments will be bright 
at the top and unreadable at the bottom.  Since the fixtures I bought 
were end-emitting LED lenses, you'll also want to make the light box of 
the instrument cluster more reflective; I painted the inside of mine 
silver.  The Digital clock is especially tricky because it is not 
back-illuminated as it appears.  It uses a clear plastic light guide to 
direct illumination onto the face of the clock via its sides.  This 
design depends on the radial illumination of a standard incandescent 
bulb.  Since the LED units are end-emitting only, you'll need to come up 
with a way for the LED illumination to reach the Light Guide... I 
created a cheesy foil  "box" that reflects the light so that it reaches 
the guide, and it seems to do the trick.  It looks like 
superbrightleds.com now sells a squared, side emitting LED bulb without 
the twist-lock; I may try fitting one of these bulbs into the original 
OSRAM sockets to see if  this improves the setup.)