resoldering circuit boards

[stevee]

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

 

[Boris Mohar]

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

 

[James Sweet]

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

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.