[41] Odd display problem

[jebem]

I would recommend the Service Guide, in case you haven't got copy yet.
It is available from here (MoHPC).
I really recommend it, as it contains very detailed instructions for diagnosing and troubleshooting the 41.

From what I understand, when the CPU is running, the signal PWO is at high level and then the lcd driver uses the SYNC signal as a timing reference. When PWO goes off and the stby mode is active the cpu DPWO signal is high to allow the internal driver clock to run for a period of 10 minutes.

Besides that, the CPU controls the source voltage to be applied to the circuits and LCD.
When the LCD is in active state (in run mode or in stby mode), the power supply should feed a stabilized 6V supply to +Vcc.
However, when it goes off (sleep mode) the supply voltage goes below the battery level.

I would start by checking for the proper +Vcc voltage, probably the power supply IC is damaged, or the battery supply is insufficient.
You may also check capacitors C9 and transistor Q1 and Q2, as it are related to the cpu stby mode switching.