resoldering circuit boards

About a year ago my '92 960 started a wierd deal. It would die while
driving but then restart after 10 or 20 attempts, then run fine. This
would happen infrequently, maybe once a month or sometimes several
times a day.

I couldn't find anything wrong. No codes and of course it never acted
up while I was working on it. After getting advice from this group I
resoldered the circuit board in the fuel pump relay. The car ran fine
for about a month, then started the same thing again.

After a few months it got worse. It would die almost every time I
drove it, usually 2 or 3 times in a row, then run fine.

I took the fuel pump relay apart again and found cracks in the
soldered connections that I had previously resoldered. The first time
I did it I didn't add any solder to the connections, just melted the
solder. I guess that was a mistake. The solder connections were
paper-thin and recracked. This time I added a drop of solder to each
connection. So far, so good.

So, if you resolder a circuit board, add a little solder to each
connection. Of course, don't use acid-core solder and be sure to get
the connections hot enough for the solder to flow freely but not hot
enough to burn the circuit board.

Steve Elms

 

That is a common problem and a solution. Do not be shy on solder. The relay
armature carries current and its mounting pins often fail. When I do this I
also clean the contact lightly with fine grit abrasive paper. You can glue
two pieces of abrasive back to back and cut a stiff sliver which will work
like a small file.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

Yes, you should always add a bit of solder, the flux cleans things up
and allows the solder to flow. If the old stuff is really crusty, remove
it with some desoldering braid or a sucker and flow new stuff.