[time-nuts] 5370a manual

Chuck Harris cfharris at erols.com
Wed Mar 7 17:50:33 EST 2007



Didier Juges wrote:
> Well, one thing for sure, in both my units, the chips are not anywhere near ready to fall off. I need a crow bar to
> take them out...
> 
> Same thing with the PWBs themselves, the card edge connectors are extremely tight, that's one reason I am puzzled by
> the problems, there seems to be plenty of contact pressure.
> 
> However, the sockets really look like the cheap type, tin plated, not the gold plated, machined contacts type.

Oh, Oh!  One problem with the cheapy tin plated sockets is they develop tin
whiskers that make minuscule little short circuits between the pins.  Bump
the board, and they come and go.

I have solved this problem on some units by blowing high pressure compressed
air all around the sockets.  Apple used to tell their service technicians to
remove the circuit cards, and smack them hard edgewise on one edge.  Same for
the mother board.

The only long term solution is to replace the sockets with something that doesn't
have any tin plated sharp edges.

-Chuck Harris



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