[sdiy] SH-101 repair question

[Michael Bacich]

On Apr 2, 2006, at 11:15 PM, Mikael Mørup wrote:

> Maybe i should just reflow all solderpionts like Rude66 did with  
> he's :-)

Yes, that is exactly what you should do.  Just do it.  It's easy,  
cheap, and painless.  While you're at it, resolder every connection  
on the whole board.  What have you got to lose?  Think of it as  
insurance against future failures.  Really.

Your instrument was soldered in the factory on a crappy wave  
soldering machine, which left just barely enough solder on the  
connections to hold the parts in place and allow the circuit to work,  
but certainly not enough solder to withstand 10 to 20 years of  
rocking and rolling.

When are people going to finally start getting it that 90% of  
electronic problems are electromechanical problems?  When things stop  
working, the first thing people suspect is some sort of major chip  
failure.  After that, some kind of mysterious, inexplicable passive  
component failure.  In most cases, both of these are very, very  
unlikely.

Compared to cold solders, broken wires, dirty contacts, etc. --  
actual failed components are extremely rare.  Even the mythical  
electrolytic capacitors that are "so old that they're ready to  
fail".  Naturally, there are plenty of anecdotal stories to the  
effect of "I replaced the capacitor and the LFO started working  
again!"  Guess what, newbies?  It wasn't the new capacitor that fixed  
that LFO, it was the simple act of soldering another one in!  You  
would have most likely gotten the same result by simply reflowing  
solder on the old capacitor.

Yes, I know that components do fail, sometimes even unlikely passives  
such as resistors (Harry B. claims to have had to replace many  
mysteriously failed resistors in his Prophet V at one time, and he  
definitely knows the difference between a cold solder and a bad  
part).  Remember, I did say 90%.  But anyone who has done a LOT of  
repairs knows exactly what I'm talking about, and though they may  
quibble about the exact percentage, they wouldn't argue my basic point.

One more thing while I'm still perched on this soapbox -- There is  
something to be said about NOT replacing old parts with new ones in  
an old unit (unless they are definitely proven bad).  That is, the  
old parts have a History of Reliability, the new ones don't.  Think  
about it.

Anyway, good luck with the repair, Mikael.  If you determine that you  
really, really do have a bad capacitor in there, congratulations.  I  
will still stand by my rant, and by the 90% statistic that I,  
admittedly, pulled from my ass.  Keep in mind, though, that it's a  
very experienced ass.  Wait a minute, that didn't sound right....


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