Re: [Amc-list] Inst. cluster lights

[Tom Jennings <tomj@xxxxxxx>]

Keith Evenson wrote:
> Hey, does anyone know if there is a modern replacement light bulb for 
> an early AMX instrument cluster? I have a 70 Javelin and a 68 AMX On 
> the 70 the entire instrument cluster is lit up very well but on the AMX 
> I am lucky to see most of the speed O.  There are bulbs in all of the 
> wholes and they work but they all seem so dim it is hard to see 
> anything. Has anyone come up with a fix for this? Any help would be 
> great.

Have you taken the bulbs out to look at them? I've found two things that 
over the years contributes to the candle-in-a-dark-cave dash effect.

* The bulbs themselves get silvered on the inside! The filament metal 
evaporates and deposits on the inside glass. The lamps still "work" but 
are super dim. Replacement time.

* The heat from the bulbs discolors the white plastic in the dash 
assembly to a greyish yellow. Requires disassembly and cosmetic surgery, 
usually flat white paint.

* The heat from the bulbs causes convective air flow and pumps dust and 
smoke through the gauge assembly, giving everything a dirty film. 
Cigar/cigarette smoke is ruinous here! It's really noticable!

* Heat and age warps the other plastics in there, like the little tubes 
and guides that separate TEMP OIL ALT GEN etc from each other, causing 
light to leak in and out.

I've renovated the dash cluster on my Hornet and American. If you're 
good at plastic car models, or model railroad type work, it's easy and 
fun, once you get the miserable thing out of the car. On warped parts, 
you have to improvise, but a lot of the parts are not seen once 
assembled, so buildups with epoxy and plastic and paint work fine.



I've used LED lamp replacements, but there's problems with those that 
I've used.

One, LEDs are very directional, so they're really bright in a narrow 
beam. However, if you look inside them carefully you'll see that they 
are almost entirely clear plastic, with the LED down near the base. 
Hacksaw the tip off, and leave it rough. This diffuses the light and 
mostly does the trick (they look like crap in your hand though :-). You 
can also run rough (100, 220) grit sandpaper over the "bulb" and get 
sort of the same effect.

For dash illumination, the lamps need to put out a lot of light 
SIDEWAYS, eg. 90 degrees from the socket direction. LEDs put out light 
straight out of the socket. Not compatible.


Two, for some applications they don't draw ENOUGH curent! Alternators 
and oil idiot lights. As I discovered, even modern 3-wire GM style 
alternators need "some" current through the idiot light to turn on. An 
old fashioned lamp draws like 100mA - 300mA, and the LED lamp is like 
25mA. My alternator won't start (light is on) until I rev it, just once, 
past 2000 rpm. Then it works great. One of these days I'll put it back...

The oil idiot light, this seems silly, but is very annoying... the LED 
draws SO LITTLE CURRENT that water on top of the sender screwed into the 
block makes the light come on dim.
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