PbF and eyelets

[N_Cook]

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. Other repairers regularly finding this failure
mechanism also?
This time 2009 Revera Fandango valve amp . Needless to say problem is
with one of the combined pot and pull-switch , awkward to desolder.
So what is the function of eyelets other than to bridge gaps in pcb
holes, for resourced components with smaller pins than original source ,
and so incompatible with pcb drillings otherwise , for stuctural solder
integrity.
Perhaps with proper solder they made more robust joints but for RoHS times ?

[N_Cook]

8 of 9 eyelets stayed on the component on desoldering, the duff one
stayed in the pcb, its pin neatly sliding out of the eyelet.

[pf...@aol.com]

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

[amdx]

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

[M Philbrook]

In article <o31tao$52n$1...@dont-email.me>, noj...@knology.net says...

a via ?

[amdx]

Well, it's been over 30 years so it could have been vias,
but I recall it as eyelets. I still have it I guess I could open it up.
Naw, to much trouble to get it out of the closet.
Mikek

[N_Cook]

I suppose part of the problem, the pins are square cross-section , not
round. Then localised stressing edges for tinpest to develop.
Remedial action will start by grinding back to an axial surface on all
such pot pins, on the solder side of the pcb before resoldering. Then
what other components will be eyeleted as well will need such attention,
the main electros yes, minor electros will they be eyeleted , 1W and
above Rs also, difficult to visually tell. I suppose the rule is
anything big is likely to be eyeleted, plus any component resource with
smaller pins.

[N_Cook]

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

[ohg...@gmail.com]

Motorola had their "famous" Placir printed circuits in the 60s, and they were notorious for connection problems between the top and bottom layers. The only solution to permanently repair these was to hard wire the top to bottom.

GE in the 70s had a line of TVs that used double sided boards with hollow griplets crimped through the board and covered with a thin layer of solder, and these would develop a dozen or more gimpy connections. Flexing the main board would cause all sorts of color, sync, brightness, video, sound issues etc. Resoldering them was difficult because the boards would out-gas badly when the griplets were heated causing cold joints. Instead of hand wiring the 50 or more griplets, I solder one side thoroughly feeding in lots of solder, turn the board over and remove the excess solder that came through, resolder that side thoroughly, and turn it over again and reflow a third time. The outgassing usually stopped by the second pass. They never came back after that.

[jurb...@gmail.com]

>" 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. "

I am not straight on this eyelet thing. Does that mean the plated through holes ? If it is like a rivet type thing they used to be called griplets.

They used them in some TVs with two sided boards that were not plated through holes. They used to break free and wreak havoc.

Then we got the plated through holes without anything in them. What your buddy did might be called "pinning". Turns out some of the Dolby boards on the Sansui 9090DB went bad this way some audiophiles consider this pinning to be an essential part of the restoration process.

It seems that on some boards the eyelets or griplets simply forestall the problem, not prevent it.

[N_Cook]

A good dialect word for the appearance of PbF - claggy, a conflation of
clumpy and slaggy

[jurb...@gmail.com]

>"Resoldering them was difficult because the boards would out-gas badly when the griplets were heated causing cold joints."

We learned to cookem. Seriously, lay the iron on it and watch it bubble for a while. Some of them eventually stopped bubbling but some didn't. Those that didn't were usually sufficiently cooked to work.

I remember those AB chassis'. Now, they wouldn't even be considered for repair or anything like them. Even a flat screen that size today, if it is not fixed in five minutes it goes into the dumpster.

But that was then.

[John Robertson]

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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[Benderthe.evilrobot]

"N_Cook" <div...@tcp.co.uk> wrote in message
news:o316t8$f1i$1...@dont-email.me...

Eyelets are a PITA whatever solder you use.

A couple of monitor manufacturers used them for the flyback transformer pins
to prevent dodgy soldering resulting in a fierce arc that burns a hole in
the board.

Solder wetting round the edges of the eyelets was often worse than the dodgy
soldering, and tended to cause the very problem it was supposed to prevent.