Hi everyone,
Gilles here (male name in France).
I have a model 200 which shows an all black LCD screen.
I replaced the battery and fully charged it, no change.
I checked the voltage at the battery when the model 200 is unplugged and it’s
about 3.4-3.5v.
I can hear a click noise in the speaker when I switch the 200 on and also when
I press the reset button.
But, appart from that, nothing seems to occur.
I checked the CPU clock and it is fine.
I also checked the buses and nothing seems stuck.
Power supply for all the chips seems to be correct.
On the LCD connector, I also have some AC voltages of various frequencies.
On very rare occasions (2-3 times not in a raw), the M200 LCD screen is greyish
and the contrast pot adjustment seems to work.
But when the M200 is black from the start, the contrast pot does nothing.
I disconnected and reconnected both the keyboard and the LCD flex cables
without any change and the symptoms.
I don’t see any traces of corrosion nor breakage on the PCBs.
There is no option ROM inserted in the memory board and if I put the switch on
the OFF position, the LCD screen does nothing and I also hear no click noise in
the speaker.
If I switch it ON, the LCD goes black again.
I’ve read the mails related to the same symptoms and used them to check things
here and there but, well, no joy !
I have a multimeter and an oscilloscope but don’t know what else I could check.
Any suggestions ?
Thanks in advance for your help !
Gilles
