From: Patrick Jankowiak (eccm@swbell.net)
Date: Sat May 17 2003 - 21:02:29 PDT
In the quest for brighter instrument lighting in the diesel M35A2, I
have done some experimenting with several 28V instrument lamps. All
plug right in.
In the data below, "MSC" is Mean Spherical Candela, a measure of
average intensity the lamp delivers to the inside of a test fixture
composed of a spherical surface of a standard area.
As to bulb sizes, the "T" number is the diameter of a Tubular bulb in
1/8's of an inch, that is, a T3 1/4 is 13/32" diameter, and the T4 1/2
is 18/32" diameter. The T4 1/2 lamps mentioned are slightly longer
than the original lamp, but do fit in the fixture.
Information about the lamps specifications was found in the Chicago
Miniature Lamp catalog online at:
(http://www.chml.com/electric/index.cfm)
Nortex Electronics in Fort Worth, Texas has the 1873's and 1495's for
50 cents each:
(http://www.montagar.com/~patj/nortex.htm)
original:
number: 1829
MSC: 1
current: 0.07 A
comment: T3 1/4 bulb. baseline for comparison. Original lamp. 1000
hours.
number: 1873
MSC: 3
current: 0.2A
comment: T3 1/4 bulb. 7000 hours. (Roughly equivalent light output to
the 28V 0.17A type 1864 but with longer life than the 1864's 1500
hours.)
number: 1495
MSC: 6
current: 0.3A
comment: T4 1/4 bulb. clear. 500 hours.
number: LTX1495R
MSC: 6
current: 0.3A
comment: T4 1/4 bulb. translucent red coating. 500 hours.
number: GE1495R
MSC: 6
current: 0.3A
comment: T4 1/4 bulb. opaque red heat-resistant coating, diffuse
light. 500 hours.
Results:
The 1873 lamp gave noticeably more brightness than the 1829 and did
not seem to harm the screw-in lamp covers (the red plexiglass filter
thingies with blank curved fronts that screw into the dash over the
lamps).
The type 1495 lamps gave exceptionally nice brightness. There was not
very much difference in brightness between the red and clear versions.
However they are a very close fit to the screw-in red lamp covers.
They generated much heat. It was found after about an hour, that the
1495 series caused some micro-blistering of the red plexiglass part of
the scew-in lamp covers. One of the covers had stuck to the lamp bulb
after it cooled, and the lamp had to be turned back on until the
assembly was hot enough again to remove the bulb from the screw-in
lamp cover.
Conclusion:
Substitute the 1873 for the 1829 safely for more brightness. In
applications other than the M35's dash panel where lamp heat is not an
issue, the 1495 is exceptional.
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