HP 2100A Restoration

Glen Slick glen.slick at gmail.com
Sat Jul 17 18:27:23 CDT 2021

On Sat, Jul 17, 2021 at 2:28 PM johnr at grebnesor via cctalk
<cctalk at classiccmp.org> wrote:
> Hello,
> I came across a web article in which you discussed restoring an HP2100A. I spent many years working on this computer and have the front panel. I am doing some work on it to produce a display for fun. I am replacing the incandescent globes with LEDs and using a Raspberry Pi to control them.
> The question I have is, do you know an easy way to remove and insert globes in the front panel switches please?

The HP 2100A front panel uses T-1.75 Bi-Pin base miniature lamps. The
last time I replaced some, if I remember correctly, I used Chicago
Miniature CM7361 lamps for replacement. I forget if I was able to get
a grip on them at all with needle-nose pliers to pull them out, or if
I used something else.

If you look for purpose built tools it appears that there are a couple
of common styles.

One style uses some sort of flexible plastic or rubber tube that is
just the right diameter and wall thickness that it can be pushed on to
the lamp, and then maintain enough friction on the lamp to pull it out
when the tube is pulled out.

Another style uses a metal tube that is split along its length that
can be pushed on to the lamp when the halves of the tube are
separated, then the halves of the tube can be pressed together to grip
the lamp so it can be pulled out when the tube is pulled out.

An example of the second style that shows up in a lot of lamp
extractor searches is the Jonard


At somewhere around $30 for those tools I haven't been curious enough
about buying one to see if it is suitable for removing and inserting
HP 2100A front panel lamps.

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