[41] Odd display problem

[emece67]

(04-27-2015 09:13 AM)Frido Bohn Wrote:  Do you have any ideas why this could have happened, e.g. moisture or discharges during manipulation?

When fixing the broken posts problem, I used a Dremel in some places to remove some plastic. Not wanting the plastic dust to enter inside the display or key domes, I covered both keyboard and display PCBs with an adhesive tape. I've made such thing many times before but, who knows, perhaps this time some electrostatic charge managed to built up in the tape.

In any case, the datasheet of the display drivers claims that the on chip oscillator is controlled by a flag, called IAF from "I Am First", whose state can be altered by high loads on the DATA line. Apparently, the first one of the 2 driver chips, that tasked to start the oscillator, is not really aware that it is the first in the chain.

I'm studying ways to overcome such behavior, perhaps with an external oscillator.

Regards.

p.s. I do not know why, but I'm having a bad time with electronic glitches. Two days ago I managed to get the (almost) impossible: I bricked a hp30b when upgrading it to a wp34s. My last attempt will be to use a JTAG probe to try to revive it.