Woodstock Low Power

[Harald]

(01-09-2018 11:42 PM)PANAMATIK Wrote:  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.

I needed to remove half of the sockets because the spacing between the anode and cathode driver was different on my PCB. I then inserted your PCB and realised it didn't sit low enough. maybe the pins on this late 25c are a bit shorter. I couldn't get the LED module to make proper contact. So I removed the remaining sockets and soldered the pins directly to the PCB.

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

Yes, I double checked that.

Quote:3.) Does the PRGM/RUN switch work?

Yes it does.

Quote: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?

I removed all the components except the charge resistor and diode and one resistor below the display.

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

No, it makes no difference.

Quote: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.

Yes, it does.

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

I will have to check this more carefully again.
Edit: I checked all 6 lines on the keyboard connector against each other. The lowes resistance I could find was 80kOhm. Most of them are above 1MOhm.

Quote: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.

That was what I was trying to achieve by measuring the /SHDL signal and then turning on an off the GPS. Unfortunately this doesn't work anymore, as I can't type anything but zeros :-| I'll have to solve that problem first.

Quote:Bernhard

Thanks for your support!
Harald