On 2016/12/17 12:25 AM, N_Cook wrote:
On 16/12/2016 23:29, amdx wrote:
On 12/16/2016 1:11 PM, wrote:
On Friday, December 16, 2016 at 12:07:12 PM UTC-5, N_Cook wrote:
Third time in as many months, usual PbF phantom problems, solder looks
fine but no wetting between eyelet and pin and grey (tinpest?) pin,
even
after desoldring.

I will render an opinion here based on my experiences with
conventional lead-containing solder of differing natures.

a) Non-Eutectic solders will solidify in a non-linear fashion as it
cools.
b) My experience with 60/40 and 50/50 solders with wires is that the
cooling is often based on the wire as it is a heat-sink.
c) Dynaco equipment uses a lot of eyelets set in circuit boards.
d) Using solders as described above, on more than one occasion I have
gotten visually excellent connections that simply twirl in the eyelet,
as the solder cooled (dumped heat into the wire) so fast that the
shrinkage pulled it away from the eyelet before it was actually solid.

This is purely anecdotal.

Today, I use only truly eutectic solders on my electronics (37/63
lead/tin) - with a very few exceptions, when for one reason or another
I need to use silver bearing solder. In those cases, I use 96/4
tin/silver, and great care not to move anything as it cools.

Peter Wieck
Melrose Park, PA


I had an eyelet problem 30 years ago on my Philips CD player.
I couldn't fix it, so I sent it to Philips Repair. I worked at an
authorized service center at the time.
The sent it back saying they could not fix it.
I mentioned it to a fellow tech and he said, "let me look at it".
He put a wire through each eyelet and soldered both sides.
That corrected the problem.
Mikek

If you can thread wire through, I'd call those vias.

Some boards from the 70s used eyelets for their vias. They would be
pressed into place, and over the years corrode enough to become
intermittent.

Speaking of vias: the first coin operated video game - Computer Space -
had a buss style motherboard (with sub-boards that held the logic) that
was double-sided but they didn't plate the holes through so they put in
tiny wires and soldered those top and bottom! I've also seen other early
game boards that had plated through vias, but the holes were offset
top/bottom and sometimes there was just a tiny bit of copper actually
carrying the signal/current. Those were fun to troubleshoot when the
copper corroded and several connections were lost.

John :-#)#
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