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

[anthony]

I got a a Yamaha FL100 flanger (the one that uses an MN3208) for a good 
price on eBay. I don't recall what condition the description said the unit 
was in because I didn't care when I bid on it. I always open up and give 
effects the once- or twice-over whenever I buy them. Usually to check for 
any obviously bad things and often to plan for modifications.

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...)

I was also alarmed that the unit came to me with a battery installed, but 
fortunately it doesn't look like it has been stored in a closet this way for 
10 years. And Yamaha's method of opening the battery compartment beats even 
Digitech with the ease with which it is done.

So you find me on the verge of trying this baby out for the first time. But 
I'm already fond of the atrocious magenta color of the trim & print on this 
thing; even the typical huge YAMAHA brand painted in big magenta letters on 
the back of the unit. I think I may just seak out other Yamaha stompboxes in 
the future and I've decided this before I've even fired it up.

I'm curious to see what putting an MN3205 (is there a BL3205 yet?) in place 
of the MN3208 would sound like. But for now, I'm more curious to see how a 
flanger is pulled off using such a huge BBD. I already have to modulated 
MN3005 delays anyway (albeit in rack units...).

I'd love to have 2 of these remounted in a rack for my MKS-50 (there that's 
how I'm tying it into synth-DIY...). I'd still deck it out with the magenta 
pointer knobs of course...


Cheers,
Anthony