> Not to avoid the invoice

Only joking,of course.

> My question was because some of the feeders (1 out of 40~50) stops
> working and in most cases the problem is the DS1307 that is damaged. 
> If I
> replace it, everything is up and working again.
>
> My theory is that ESD is being generated and when the user approach
> the machine a discharge is produced trough the 7 segment displays 
> that you
> can see on the pictures in the OP links.

Is there any conductive path from the outside to the inside. Frame 
around display, switches, other controls?

If the PCB was at ESD potentials is the DS1307 in the obvious path?

Can you introduce system ground into the area that users touch? (ie 
grounding something conductive that may be floating at present.)

Can you kill it with a spark discharge gun or by charging up people 
and zapping it with a finger?


        RM

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