exactly, pcb fault caused the problem and
very hard to locate it.

I met such situation twice recently. 
It seems even for home made pcb,
quality assuarance is still needed!

Such as via quality. I think of
using metal cotten at bottom been
connected to one pole, and another
pole of meter goes through every via.
Any body has same thought?

BR,

Paul

----- Original Message ----- 
From: "Russell McMahon" <apptech@paradise.net.nz>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, April 26, 2005 8:09 AM
Subject: Re: [EE] my led driver messed up.


> Designed by protell99se,
> made double-sided pcb by myself,
> but my led dot mitrix diver didn't work
> as hope. It seems has interfering
> from some where.
> 
> Can you
> 
> 1.    describe the nature of the interference and
> 
> 2.    provide a circuit diagram. It is MOST unlikely that a PCB layout 
> problem would cause LED problems unles syou have very significant 
> energies being routed nearby. It is more likely that there is a 
> circuit fault bewteen the final and prototype versions. The above is 
> if there are mainly LEDs involved. If you have extra transistors etc 
> then it is possible for interference to cause problems BUT this is 
> most likely to be caused by a desif=gn error. eg transistor base not 
> pulled down when off etc.
> 
> Providing us with the above infoprmation will greatly help us to help 
> you.
> 
> 
> 
> 
>         Russell McMahon 
> 
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