[sdiy] New eBay score: Yamaha FL100: why do solder joints fail?

[Roy J. Tellason]

On Thursday 08 May 2008 16:14, anthony wrote:
> I like the way the way this Yamaha is built and they use primo parts all
> through: NJM4559L op amps (I'm a sucker for SIL op amps...). The only bad
> thing about it it would seem is the use of PC board mounted 1/4" jacks
> because even though there is plenty of support for them on each side of the
> box is looks like every single solder joint has jimmied loose. Same deal
> for the power supply jack. (Already fixed - no worries...) I was wondering
> if the conditions when the unit was soldered played a big part or maybe
> even the kind of solder they used? I always use 63/37 solder because it is
> eutectic: that is it doesn't super-cool so it is far less likely to form
> cold joints. (Much less headaches when I'm soldering wire to broken-off
> pins on IC's for sure...)

There are definitely issues when it comes to Yamaha gear and soldering 
connectors...

If you look at the solder joints around the power connector,  for example (and 
I'm assuming here that it's one of those with a pin in the middle like you'd 
have for a lot of the common wall warts) there will be _way_ more solder mask 
around those pins than I can see as being necessary or desirable.  This was a 
real common repair for a lot of those portasound keyboards back when we had 
the shop,  they'd have it on a table,  connector plugged in there,  something 
would bump it,  and it'd rip the foil right off the board.

Cleaning a bunch of that solder-mask off,  putting a bit of wire across any 
breaks,  and building up a nice blob of solder on there usually took care of 
the problem.

I don't know if it's because they *really* want to use less solder,  or 
because they underestimate the stresses being placed on those connections by 
abusive musicians <g>,  but I did notice that later units had a different 
connector,  one that attached to the case itself with two small screws rather 
than relying on only the solder joints to hold it in place.

But yeah,  it's a real common thing with them for some reason.

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