In the end, when it was all back together, it was silent, so I have to
conclude that it *was* a bad joint. But what makes it so frustrating from
a
commercial 'let's make some money from this repair' point of view, is
that
unlike conventional leaded solder joints when they go bad, you just can't
provoke lead-free bad joints to show themselves by any of the time-tested
and trusted methods.

I hate the stuff with a passion :-(

Arfa


Is one of your inducers an engraving tool with an insert of a nylon bolt
with "sharpened" end/tip? to pcb only , no direct contact to any SMD of
course as likely to flip them off.
Unfortunately you have to monitor the o/p with phones because of the noise
of the engraver. So what sort of solder do you think it was ? high Cu and
tin ? at those sorts of temp very high probability of temp induced Si
failures. Manufacture date?



I tend to use a Biro pen, a hot air rework station (turned down to 100 deg
or so), a can of freezer, and the butt end of a bloody great screwdy. Oh
yes. And a lump hammer ... :-)

Seriously though, with normal leaded joints, I've never found it necessary
to use anything other than 'gentle' methods to pin a bad joint down to
within a square cm of board, which is what makes lead-free joint problems so
incredibly frustrating. I get them all the time where you've only got to
look sideways at the board, and the joint will go bad, and yet no amount of
provocation will bring it on when it's right, nor get it back when it's
wrong. And when you do eventually find it, the component is often hanging
out of the board - except you can't actually see that it is until you tug on
it, or come to re-solder it, when the solder flies away from the component
leg to form a ring on the pad, leaving the leg looking as though it's never
been soldered in its life ... And how many times do these lead-free bad
joint jobs bounce a couple of weeks later ? Can you imagine the implications
if the rotten stuff ever does find its way into avionics and other
life-preserving areas ? New programme on Discovery ? "Aircrash
Investigation - The Lead-Free Years" ?

As to the Quad. It was from their "Lite" series. The owner's user guide says
"03 - 05 Issue 1" inside its front cover so I'm guessing maybe 2005 ?? which
is before the 'official' lead-free introduction cut off point of June 2006,
but a number of manufacturers - notably Sony for instance - were
manufacturing with the stuff well in advance of that date. There is also a
note in the back cover about EC compliance requirements that it conforms to,
but they are about EMC and voltage safety. No mention of lead-free.

I suppose it's possible that the thing was not built with lead-free, but it
certainly looked and behaved like the stuff. Which brings us back to a point
often made by Mr Cook. How do you tell for sure when the board isn't
categorically marked ?

I really don't know what alloy had been used on this. Only that it had
trouble melting on the end of my normal continuous-use
temperature-controlled bench iron, even when set at max. It did melt ok with
the 140 watt Weller gun on it, but even with that, it only 'flowed' fairly
normally. Anyone who has ever used one of these beasts, will know that under
normal circumstances, a small joint will be pretty much boiled on the tip
....

Arfa