> All what I did was change the cap on the reset pin,

>From what value to what value?

> and put another cap on the spare
> voltage input of the pic.

which changed it from what value to what value?

> By now, every thing works fine.
> Thanks a lot for all your comments.

BUT it sounds like you MAY have changed it from marginally unstable to
marginally stable.
ie, you should have adequate capacitors there BUT a small value should
be enough.

It seems likely that a spike was getting into you power supply and
that you have damped it down enough "for now". Understanding what was
happening (and probably still is) is essential if you want good
reliability.

An oscilloscope on the 7805 input and output should prove of value.
IF you are getting a significant spike there then the diode
arrangement you are using (on the PCB) is probably acting like you'd
expect that it might.

Trying changing the caps back and putting diodes across the actual
relay coils (if they are not there already as well as where they are
shown on the PCB) may be educational.

Fixing something is good. Knowing what was wrong and how the 'fix'
worked is better.



 Russell
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