HP-67 1705A01234 [erase other's cards, writes and sometime read back its own cards]

[albertofenini]

Hi everyone

This is quite a weird one ..
Any card previously written is erased when read by this HP-67
This happens also with what it should be a write protected corner clipped card
It is however a blank card, recorded and than corner clipped

I have checked what was obvious to me i.e. :
the W/PRGM switch really switches from one state to the other as it should
PGMSW pin at CPU board connector only goes to GND only when W/PRGM switch is moved

I still have to try if the HDS and WPS sequence is correct when a card write protected and one not write protected are inserted

I have written a simple program (math operations) recorded it with this HP-67 and while it is
not read by any other HP67, it is sometimes read back by this unit

This happens since I have slightly adjusted the pressure of the wheel

While I have not been able to record CA and CB, I have successfully recorded RA and RB when reading a card
and WA and WB when writing a card.

As always, any help will be greatly appreciated!
Take care !!!

Pictures here : HP-67 1705A01234