Problem with a strange output on LCD

[sardarg]

I've used the Circuit from the website
Shift1-LCD Projects

But getting junk value on display.. Sometimes the circuits works fine for 5-10 mins and then displays random characters mostly " w ? w? : w?" and sometime the second line of LCD disappears..

Kindly help me finding the problem.. I have checked the codes on a prototype circuit and it is working fine but when i converted this to a final PCB now getting this result.. I have checked the circuit layout, the schematics each and everything possible mistake that could have been there but no improvement..

Can anyone suggest me what to do?

 

[horace1]

Re: LCD Strange Output??

the timing of writing to LCDs can be critical (they are very slow in computer terms). Try putting a few millisecond delay after writing a character.
does it work if you write a single character? if not it is possible you gave the data lines incorrect - put it in a loop and check the bits with an oscillosocope

 

[sardarg]

Re: LCD Strange Output??

Thank U "Horace1" i'll try these steps but i've added some delays of 20msec after writing each line..
One more thing i have noticed is that display changes by changing value of Capacitor on the Regulator Output.. Currently value is 0.1uF as mentioned in Datasheet but when i change it the randomness varies time by time say for 10uF cap error occurs after 9mins but not fixed at 9mins sometimes it occurs between 3-5mins..
Is this a power supply problem thats creating LCD junk data..??

 

[horace1]

Re: LCD Strange Output??

could be - the 5V power supply I used is

 

[sardarg]

Re: LCD Strange Output??

Thanks Let me Check this also..

 

[qwertyuiop415263]

use 10uf capacitor with the supply