LCD Display Related Problem

[desmond1310]

Hi, This problem occurs somewhat randomly. I have done my project on a PCB and upon powering on my device, my 16x2 LCD displays nothing but 2 long black bars.
I decided to press my wired connections made through molex connections to ensure contact points. After that action, I finally got my display working properly.

I then turn my power off (all switches off) and turn them all on again without touching ANY wired connections, and suddenly my 16x2 LCD displays nothing but 2 long black bars AGAIN!

I tried to find the root of the problem, but it happens too randomly. Sometimes it displays black bars, sometimes it displays correctly. I checked the connections between my wired connections and I ensure you they are connected and no short circuits! Is this a grounding problem? My PCB ground area covers the majority PCB area though. Please advice thank you!

[yonghui]

hi,

the contrast preset got problem?
try to check tat.



regards,
yh

[desmond1310]

@yonghui,

you mean the potentiometer connected to pin 3 of my 16x2 LCD screen? i doubt the problem lies there. Checked already and it seems to work fine. What sort of problems should i be seeing from the contrast preset?

[ABSF]

I decided to press my wired connections made through molex connections to ensure contact points. After that action, I finally got my display working properly.

I then turn my power off (all switches off) and turn them all on again without touching ANY wired connections, and suddenly my 16x2 LCD displays nothing but 2 long black bars AGAIN!

Intermittent faults are usually the most difficult to troubleshoot. from your description, i'd suspect a bad joint in the molex connector, or one of the wires is almost broken due to carelessness when stripping the insulation. Did you buzz the wires one by one shaking the molex while buzzing?

Allen