DIYbanter - View Single Post - Dirty connector update-more info

Jon Elson[_3_]

wrote:

Thanks so far Cydrome, Matt, and Jon for reading and replying with
suggestions for finding the board problem. Last night I identified
every device on the board and made a list.

OK, not an opto anywhere, so my idea is toast! So, is it clear that
powering off doesn't fix it, but reseating the board DOES, at least
temporarily? If so, that pretty much indicates a connection problem.
Most of this stuff was wave soldered, so it is not real likely there
are bad solder joints on the chip-board connection. What type of
connectors are on the board-backplane connection? If Elco Vari-lock
or similar contact, they need to be squeezed. My old Allen-Bradley 7320
control was all Elco Vari-Lock contacts without the plastic housings
on the board contacts. This allows them to get bent apart when the board
is wiggled out. Elco vari-Lock contacts are hermaphroditic, and sort of
a narrow fork. The close faces of the tines are angled, and wipe against
the other contact, assuming the tines are parallel.

So, I have no idea whether your control uses this type contact, but I
definitely ran into this on that old A-B. Card edge contacts can get dirty
or sprung after many insert/remove cycles.

Jon