Woodstock Low Power

[PANAMATIK]

(01-09-2018 10:39 PM)Harald Wrote:  Any idea what the problem might be?

Some questions and suggestions:

1.) First I do not recommend to solder the LP circuit without sockets, because you can never remove it without misaligning or loosing all these pins. It is a lot of work to solder them again properly aligned. The LP should work with low profile sockets. I made two units, which can be closed nicely.

2.) I assume the keyboard connector is plugged in the right way, because the "div" key is working. If it is plugged in the wrong way, this doesn't harm anything, but keyboard rows and PRGM/RUN switch are in wrong order.

3.) Does the PRGM/RUN switch work?

4.) Did you remove the original ACT chip? I never tried with it, because both of my units had it already removed. Perhaps it pulls some keyboard lines low?

5.) Does it make a difference if you disconnect the Bat+ from the GPS supply?

6.) If the display shows "HP-25 LP" at startup, this proves that the PIC is OK and all socket pins (9+3+3+3+3+1) display driver pins are connected properly.

7.) The problem must be located at the 5 keyboard lines. Perhaps there is a short in one of the keyboard lines?

8.) Can you double check, that you did not exchanged the GPS /SHDL and GPS data signals inadvertently? But this would not explain the keyboard issue.

Bernhard