TU56 lamp replacement

Tony Duell ard at p850ug1.demon.co.uk
Tue Oct 27 16:06:20 CDT 2009

> Personally, I'm surprised that you haven't repaired incandescent light 
> bulbs...  or maybe you have?

I have -- sort of :-)

More seriously, I was repairing an HP59306 relay actuator. This unit has 
some 'midget flange' bulbs in the pushbutton switches, and I couldn't 
find a supplier who woul sell 1-offs in the UK (a couple had failed). 
However, I did have some wire-ended bulbs of suitable voltage and 

So I took the old midget flange bulb and cracked the glass part out with 
pliers. Desoldered the wires from the side of the cap and the base 
contact, and cleaned out the inside of the cap.. Then inserted a 
wire-ended bulb and soldered it in place. 

The result is a 'repaired' midget flange bulb that fits the HP switchbank 
with no modifications.


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