MLDL2000 stopped working

[hth]

I got an MLDL2000 way back, but never got around to use it, until now.

It started out quite nice. I am testing some software I develop, but after a while I ran into trouble in that from time to time the whole machine goes totally unreliable. As I am fiddling with poll vectors and the key sequence parser, I thought my code was the problem, but after turning off these vectors, it is still not reliable.

It can work for a while, then it just decides that it do random crazy things with my key presses and sometimes scroll the LCD sideways a bit.

Looking at the MLDL2000 pages, I noticed that some few devices had a bug described as "In some cases the MLDL2000 may become unstable, especially after key presses.", which sounded spot on to me.

Fixed in a 1.51 firmware, I was running 1.00, so it was time to upgrade. I upgraded to 1.70 and everything seemed fine on the PC side, I could upload images and configuration.

On the HP41 side, nothing worked, it does not even want to wake up when the MLDL2000 is enabled, either using flash or SRAM configuration. Nothing, it is totally dead. If I disable the MLDL2000 using the DIP switches, I can get the HP41 to wake up, after some backarrow-ON presses.

I tried the SRAM self test and it worked fine.

Is there something else I should do to get it to work? I take the same steps as before, it looked good when flashing firmware, it reads back version number properly.

Håkan