INSTRUMENTS ILLUMINATION
The following were modified to provide LED illumination:
Main instrument cluster
HVAC control unit,
Clock, and
Instrument pod buttons.
Light Sources
The following are the two sources which have the best bulbs selection:
supprbrightleds.com (best prices), and
Superlumination (better technical data).
I have used bulbs #74, #194 and Festoon bulbs for this project.
Bulb #74
Bulb #194 (Matrix 5 LEDs)
Festoon bulb (9 LEDs)
Bulbs #94 replace main three filament bulbs in instrument cluster. Bulbs #74 can be used for all other illuminations. Festoon Dome LED Light Bulbs, available from both sources, may be used for the floor and roof illuminations. I have used blue for the entire interior.
Main Instrument Cluster
The cluster is illuminated with five #74 LED bulbs and three #194 LED bulbs. This results in uniform illumination across entire cluster. The cluster LED illumination is completely reversible and it may be returned to the filament bulb illumination if needed:
#194 LED Matrix bulbs are used in place of filament bulbs.
#74s are evenly distributed across three plastic light diffusers.
To house LEDs inside plastic diffusers. I have drilled holes into them so that LED is inserted towards the cluster (two holed in outboard diffusers and one in the middle of center diffuser).
When installed in the pod, there is very small clearance between steering wheel tube and plastic diffusers. Therefore LED bubs need to be shortened by removing colored resistor/diode housing (can be removed with pliers by twisting and pulling).
LED leads are soldered to resistor and diode leads very close to the LED. Resistor/diode leads need to be bent, at 90° angle, right above solder joint to shorten the bulb. If joint brakes it needs to be re-soldered.
Ideally, the hole in plastic diffuser should be deep enough so that LED may be inserted and resistor/diode lead wires, bent at 90° angle, are touching surface of the plastic diffuser (this is needed to achieve very small protrusion above plastic diffusers due to very small clearance available, when installed in the pod, between diffusers and steering wheel rod)
Each LED resistor/diode leads need to be connected in parallel by soldering them to wires (+12V and GND). Solder points are established by the position of the LED holes drilled in the plastic diffusers.
This light bar needs to be tested before is sealed to the instrument cluster housing, on the top of plastic diffusers. This light bar may be removed if needed, or just disconnected, and #194 Matrix LED bulbs replaced with filament bulbs to return cluster to original illumination.
5 #74 LED bulbs inserted into the holes drilled into the existing Plexiglas diffusers
5 #74 LED bulbs and 3 #194 Matrix bulbs installed
LED bulbs light bar secured on top of Plexiglas diffusers
HVAC Control Unit
This project included use of three blue LEDs. Light box filament bulbs was replaced with #74 LED bulb. Other two bulbs were used to feed 5 fiber optic conduits to illuminate the knob, sliders and Plexiglas base for the knob back illuminated bezel. This project included the following:
new bezels
new fiber optics,
new illumination for the fan Knob (provision provided - the knob has a diffuser - but no illumination done by VDO),
new bezels for knob surround made using Duratrans technology and ACAD drawings), and
deepening of the sliding knob diffuser hole depth.
My bezel with LO-FAN-HI marking was cracked. Many rebuilds I have seen have problems with them. I have spent a lot of time trying to find how to fix that. The answer is Duratrans!
Duratrans process for back illuminated bezels
Duratrans are backlit display graphics produced from color negatives. They are typically used in the display and tradeshow industries by installing the graphics in light boxes. The material has a translucent white base that diffuses the light source producing brilliant colors and allows for pure white areas in the image, such as knockout type. Duratrans prints from digital files are typically up to 50x96 with using LightJet-5000 digital printer for large format photo printing:
LightJet can print on Type C photographic paper as well as Duratrans translucent films for backlighting.
Knob bezels
I have reproduced, in 1:1 scale, bezels using ACAD and converted DWG files to metafile and then saved them as TIFF. That process results in the best resolution. TIFF format used by Duratrans process. Normal print is 150 DPI, but when asked, they may set printers to 300 DPI (normally not done for large size jobs they do). After Duratrans was printed, the entire sheet was laminated in non-gloss material to closely reflect original surface. Individual bezels were cut out then.
At the end I have used white larger fonts (one on the right side below) on the knob bezel (see illuminated bezel). These are example of the bezels I have created (TIFF files):
Knob bezels in few fonts and colors
Actual prints
Since some light can be still seen through the black bezel when illuminated by fiberptics. To eliminate this additional black film may be added on the back. I have printed my to-scale bezel on a B&W Ink Jet Laser printer using viewgraph film. I have cut out rectangular around LO FAN HI letters to assure no overlapping and maximum letter visibility when illuminated.
Secondary light filter
Climate control bezels
Duratrans prints orange as lighter red and over-all, this bezel is very close to VDO's original. Blue LED light is completely filtered by red 80 and 85 numbers. I have tried some of my bezels (these are TIFF files - actual Duratrans prints are shown below):
These bezels I played with to see if I can get better 80...85 illumination with blue LED (original red numbers filter blue light completely).
As printed on red diffuser
I have found that the last bezel shown above filters less of the blue LED light then VDO bezel. However, the only way to make those red numbers a bit visible was to add a orange filter behind them. I have tried all stage filter films - none worked. Only simple "Stick It" note pad paper, of dark orange color, resulted in passing of some red light (shown below).
New fiber optics
Five new runs were needed for illuminating:
- Fan speed knob (1 run) - new illumination not provided by VDO.
- HI - FAN - LO letters on knob bezel (2 runs)
- sliding knobs illumination (2 runs).
LED Feed For Fiberoptics
To use only 2 led bulb light sources, fiber optic runs need to be terminated into two groups of multiple runs. My local fiber optics shop terminated for me groups of 3 and 2 runs, using single bushing for each group. Bushings are epoxy filled and fiber optic runs are sanded to be flat with bushing's end. Bushing ends are attached to flat LED bulb lens and kept together with aluminum tape shaped so that both pieces remain attached (sorry about not taking any pictures):
Fiberoptic runs with bushing
Knob illumination
In the example above, 3rd run is for fan knob illumination. This is difficult to implement since 1/4 turn rotation of the fiberoptic run is required. I cut mine with a Dremel, in position such that fiberoptic cable would not interfere with gear teeth when OFF position (clearance as shown). The 1/4 turn opening will allow for fiberoptic cable being fed through in while still clearing housing of the fan speed switch. Hole must be drilled through the knob, as close to the center as possible, in correct knob position as determined by the key on the fan speed switch shaft.
Being tested
Clock
I have replaced filament bulb with blue T1.5 LED bulb (not available any more from the sources I have quoted). Bulb #74 is slightly too large. However, it may be used after Dremel-ing LED bulb base a bit to be small enough to allow insertion into the clock bulb socket. One must be careful not to damage embedded in the bulb diode and resistor.
Instrument Pod Buttons
With exception to mail light switch, and trip rest switch, remaining switches have two brightness levels - dimmer for non selected functions and brighter for selected one. Per some tests, nominal brightness @ ~20mA, can be visibly reduce when current is limited to ~10mA. After considering already inserted ~420 Ohms resistance inside LED bulb, I have used this resistance calculator to arrive at 1000 Ohm additional resistance required to reduce LED current to less that 10mA:
Above 10mA current, LED bulb brightness remains at very close level (from "tests" site linked above).
For all pod and center console instruments, except for the main light switch in the pod, illumination level is controlled by the rotary potentiometer with maximum resistance of only ~ 40 Ohms. When de-fogger, fog light or hazard light button is depresses, maximum brightness for these buttons is obtained by bypassing rotary potentiometer and feeding lamps directly from the power bus. When LEDs are used, resistor should be 1500 Ohms max. This would not resolve the requirement for dim level of illumination for dual dim requirement, therefore I did n0pot pursue this path. Therefore, I chose to implement dim feature and delay over-all system brightness level control for later.
LED bulbs are already equipped with ~420 Ohm current limiting resistor. After testing few resistors, from 800 Ohms to 1500 Ohms, I have found that in addition to LED bulb internal resistor, an additional 1000 Ohm resistor provides very clearly visible dimming, whereas 1500 Ohm resistor (total LED resistance of ~ 2000 Ohms) dims LED completely. New 1000 Ohm resistor needs to be inserted in series with LED bulb to dim brightness level as shown below for three applicable circuits.
1K Ohms resistor testing
Future upgrade to over all brightness level control may include multiple channel PWM controller which may independently control brightness levels in up to four different circuits. For now, I have opted not to do this since overall illumination is just right.
Hazard Button Circuit Modification
The mod for Hazard button (red) illumination: (Lamps USA Wiring Diagram, Page 2, zone L3) - dim light when lights are ON - bright light when Hazard button is depressed. I have soldered resistor into open circuit, crimped together two 0.5 SW/BL wires with resistor circuit wire, and heat shrunk that section of harness.
Fog Lamp Switch Button Circuit Modification
The mod for Fog Lamp Switch (green) illumination: (Lamps USA Wiring Diagram, Page 2, zone D 3/4) - dim light when lights are ON - bright light when Fog Switch button is depressed. I have soldered resistor into open circuit and heat shrunk that section of wire.
Rear Window Defogger Switch Button Circuit Modification
The mod for Fog Lamp Switch (green) illumination: (Ventilation, Heating, AC Wiring Diagram, Page 2, zone H 32/33) - dim light when lights are ON - bright light when Fog Switch button is depressed. I have soldered resistor into open circuit and heat shrunk that section of wire.
Warm temperature numbers are the brightest, but the best I could get with blue light source.
Defog button is at dimmed LED level. When rotated, it illuminates brighter.
