HP-25 Co-luminous segments

[Tom Flatterhand]

In the meantime, I was able to perform a few measurements. I measured the pins 1 to 9. Except for pin 5, I could detect a signal everywhere, which also repeated after about 3.8 ms. I took pictures of pin 1 while my daughter pressed button 9. I have attached 2 pictures of pin 1, one with the button pressed and one without.

   

   

Conclusion: I am not getting anywhere and will probably give up looking for a solution. Because except for the problem with the upper segments, the computer seems to work fine. And since the inside also looks very good, I will (probably) never try to unsolder any of the IC's there. Because this would end with my old equipment probably rather in a permanent damage.

Therefore many thanks to all helpers for your help! And of course especially to you Tony, you really made a lot of effort!

Now I need an old HP-25, one that is really damaged, so I can put in such a Panamatik chip. :-)

Background anecdote:

After 16 years I once again opened the case to my, at that time bought used, Scopemeter 123 and found out, that I have a second measuring line, as well as still small clamps. :-) And there was a cable for a COM port, which theoretically allows to establish a connection with the scopemeter via a purely optical connection. In the case is even the appropriate software for Windows 3.11!

I thought, great, then I can take pictures directly from the scopemeter display on the PC. That was also the idea. Because fortunately I even have extra interface cards installed in my Ryzen 3950! But unfortunately no floppy drive. OK, I thought, I'm sure I'll find something on the Internet and indeed I found it at Fluke:

https://www.fluke.com/en-us/support/soft...test-tools

I downloaded various versions and installed them under Windows 10. The software then tried various baud rates automatically, but unfortunately did not find a scopemeter. Finally I gave up and asked my daughter to take pictures of the screen with her smartphone. :-)