[Farmall] Repairing IH "flat back" lamps

[szabelsk at gdls.com]

Mike,

Been reading the posts responding to your original e-mail. Repairing the 
"sealed beam" shouldn't be difficult using any standard automotive style 
bulb designed for use in a headlight application.

Once you remove the crimped in bulb, measure the distance from the crimp 
to were the filament is (was). This is the location were you want the new 
filament to wind up. Too far back and you'll lose candlepower due to 
possibly being beyond the reflective surface or down into the neck of the 
reflector. Too far forward and again you lose candlepower since you're not 
making use of all the reflective surface behind the filament. Location of 
the filament is important when it comes to lights.

Take any standard headlight bulb and solder two wires to it. One should be 
on the brass base of the bulb and one on the center contact. The center 
contact is your normal power connection, and the brass base is your normal 
ground. When attaching the wire to the brass base, make sure you don't 
unsolder the small wire which comes out of the bulb near the glass. When 
attaching the wire to the center contact don't worry too much about 
screwing up the small solder point, just make sure you don't create a 
solder bridge to the brass base.

Some bulbs will have a glass insulator between the center contact and the 
brass base, some will have plastic. If you have plastic and melt the 
plastic away, that's OK. Just slide some insulation sleeving down the wire 
and into the brass base. Test the bulb too make sure it works, than fill 
the brass base with RTV, silicon, or even JB weld. You don' have to worry 
about breaking the vacuum on the bulb since it's actually a glass seal at 
the base of the glass bulb (the wires are crimped in the glass when its 
still hot and the vacuum is being drawn. The brass base is essentially 
glued onto the glass bulb  and held in place by the wires. You've probably 
seen working bulbs that would rotate in their base. That's because 
whatever was used to attach the base to the bulb let go and the wires 
weren't twisted off of internally shorted together.

Once you have the wires attached and have verified the bulb works, make an 
adapter out of plastic or some other handy material that will secure the 
bulb into the sealed beam such that the new filament is were the old 
filament sat. Glue it in and you should be good to go. Making the adapter 
out of metal won't hurt, it should actually give you a better ground 
connection between the new bulb base and the old sealed beam.

As another thought, an old style headlight socket from an older car should 
fit into the sealed beam (???). Attach a second wire to the old style 
socket base if necessary and install the bulb into the socket in the 
normal manner. Again, affix the old style socket base into the sealed 
beam.using a home made adapter. Now you should be able to pull the old 
style socket out and do a simple bulb swap if the new bulb burns out.

Carl Szabelski



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