Replaced the display in a 15c - comments and quesitons

[vaklaff]

Hello

The old 15c that's permanently on my desk was hit by a display bleed. Although very slow - maybe 5 years of progress and still not reaching any segment, I decided to try to replace the display. A couple of days ago I bought a cheap and beaten 12c of similar vintage. For the record, it's the second generation Voyager per the informal classification created by Randy Sloyer in this thread. (Randy, wherever you are, thanks! It was not the first time I learned from you.)

I spent today's rainy afternoon on it. Disassembled both the calculators, shaved the heat stakes, removed the displays, cleaned the contacts, put the 12c's display on the 15c's board. Easy enough, except some segment didn't catch up. On closer inspections, one zebra of the 12c was deformed so I replaced it with one taken from the bad display. Now the display worked flawlessly.

OK, I cleaned everything I could, the board, keys, rubber pad and so on and so forth and assembled everything back. The absolutely worst part was, as expected, the heat stakes. Using a pointy soldering iron, I first melted the remnants of the stakes. That created a basic "grip" on the board. Then I tried to strengthen them by adding the original shavings. That was very slow and very messy job. This is the results:

(The old leaking display is on the picture as well)

Despite the mess, the keyboard feels firm, well supported, with uniform action, passes the test:
.
Still I'm considering putting a sheet of foam between the board and the case. First, to minimize possible movements, second, to keep the improvized "heads" in place, in case they break off. I sure don't want them to wander around, eventually ending up in the keyboard or the display. Unfortunately I cannot find a suitable foam at home right now.

For the sake of completeness, the display test:

It's sort of a success but nobody should look inside!

Anyway. I was impressed by the looks of the internals. Exactly 40 years old but seemed like made yesterday. A beautiful piece of technology. Until I laid my hands on it, that is :-)

When I was washing the keys, they resembled some other model's keys that I washed some time ago, maybe the 65? It was more than "resembled", it felt like rewinding my memory. Is it possible that HP was using the very same shape and size of the keys for several generations? Just curious, not that's important.

What I really need to ask are these questions:

I forgot to put back the see-through plastic flap that partly covers the battery compartment. What's its purpose? Now it's too late to anchor it below the board but if the flap is important I'll think something up.

Also, there was a strip of adhesive tape on the lowest part of the board. Actually, adhesive it was no more and I didn't put it back. Again, what was it for?

Thanks!