Thanks for the quick replies and confirming my suspicion on the 5vdc.=20
The input is 24 VDC, through a LM317 from 24 VAC. There might be more to=20
that circuit, but haven't looked further since it's OK. The original PCB=20
is 2 months old, had other issues, possibly a failing CPU or memory. The=20
2nd a warranty replacement has the 5 VDC came from a local distributor,=20
and might have had the damage before, or early life failure. I requested=20
the contractor to order replacement from the manufacturer to ensure a=20
different batch, and not shop worn.

And to answer a recent question. Don't know specifically. The first=20
board failed in use, the middle of the night, the 2nd was just installed=20
with power down, on power up, the problem was there, at least shortly=20
after power up, was checking out other operations first.

On 12/11/13 5:13 PM, RussellMc wrote:
> On 12 December 2013 10:56, David VanHorn <microbrix@gmail.com> wrote:
>
>> Where are the snubbers?   I suspect you need them at the coils, and at t=
he
>> chip through the common diode into a zener to ground.
>>
> Plus the ULN2803 has on board "catch diodes" - all connected to pin 9 if =
I
> have the mental image correct - diagonally opposite pin 1. Connect this t=
o
> Vdd or to Vdd via a resistor or to ground via a zener or ... .
>
> What you are doing sounds OK.
> What is the Vin drive voltage?
> Various members of the family have different input circuits and it is
> possible to destroy some by overvoltage input.
>
>
>             Russell

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.