HP27 : decimal dot and question on keyboard

[albertofenini]

Hi everyone,
today we worked on one of our collection unit, an HP27.
It had some oxidation and we wanted to be sure to store it clean.
By doing so, we also tested some spare parts we had purchased many years ago,
these were LED display for the Woodstock serie.
To our surprise, and we wanted to share it, the decimal dot, is not a dot, but is a small triangle.
Anyone knows which kind of display is this ?

We also noticed some oxidation underneath the keyboard, we injected from the keys some
drops of Deoxit, and it worked in a way, but we are afraid the sooner or later, we will have some
bad surprises (look at the upper right corner and you will see the shadow of some oxidation).

Question is : being this completely sealed, how can we clean this type of keyboard without opening it ?
Thanks for help !!!


               

[Massimo Gnerucci]

(02-16-2019 08:41 PM)albertofenini Wrote:  By doing so, we also tested some spare parts we had purchased many years ago,
these were LED display for the Woodstock serie.
To our surprise, and we wanted to share it, the decimal dot, is not a dot, but is a small triangle.
Anyone knows which kind of display is this ?

Here's an old thread about this feature.

[rprosperi]

Interesting observation and post alberto, thanks for asking about this.

Looking at all my Woodstock machines, I've found 2 with the lower, triangular radix point.

HP-21, s/n 1604A01066
HP-22, s/n 1601A06395

Both have original LED modules as far as I know; I did not own them since new so I can't be 100% sure, but very likely these are original.

[Geoff Quickfall]

Presentation at HHC:

See page 11for displays:

http://www.panamatik.de/HHC2015Presentation.pdf

Geoff

[PANAMATIK]

In 1976 my teacher gave me his newly acquired HP-25 for learning RPN programming, it had a wonderful bright display with triangle dots. He also convinced my mother to buy an HP-25 for me and we ordered one. When it arrived I was disappointed, because it was different, the display had the square dots and had not exactly the same brightness or color. Also the pouch was darker and not the same shade of brown. I think I was very sensible and childish at this age. But anyway I loved it and it started my programming career.

Today I have several HP-25s, some with triangles, others with squares, also the one of my teacher, which he left to me many years later.

Bernhard

[Thomas Klemm]

(02-17-2019 07:50 AM)PANAMATIK Wrote:  Today I have several HP-25s, some with triangles, others with squares, …

What about those having the HP-logo:



Were they only used with the HP-29C/19C?

Kind regards
Thomas

[rprosperi]

(02-17-2019 09:27 AM)Thomas Klemm Wrote:  Were they only used with the HP-29C/19C?

I believe only the 19C (not the 29C) and even then, not all 19C's have the special decimal point; sadly, my 19C does not. This is arguably enough justification to add another 19C that does have it to my collection, but 19Cs that are fully working and in great shape are hard enough (and not cheap) to find, so it may remain elusive...

[PANAMATIK]

Another nice find when I repaired my HP-19C: The Woodstock LED displays are pin compatible to the HP-19C, but have one digit less.

Bernhard