[sdiy] Re:Need Some Advice

[Brown David]

Very sad to hear of Jonathan's lack of success despite having spent so much
time and money.  Other DIYers have made many useful suggestions; such as
finding a someone more knowledgeable than you who can help, and building
high quality kits rather than your own designs.  Regarding the second point,
you didn't actually make clear whether your synth was your own design or a
collection of modules designed by others.  It is certainly advisable to
start with the latter, preferably kits that have ready made PCBs and front
panels, all the electronic components, and adequate instructions for
building, testing and fault finding, and calibration.

The other thought that came to mind was that you have either been very
unlucky, or are doing something wrong.  I expect most of us found the first
few things we built didn't work first time.  But as we gained experience, we
became more successful.  Without knowing more about how you went about
building circuits, it's difficult to diagnose the source of your problems.
However I would make the following suggestions, based on many years of
sometimes painful experience.

Faulty electronic components are rarely the problem, assuming you've got
them from a reliable supplier and haven't damaged them inadvertently
yourself.

Most problems are the result of (not in any particular order):
1.  Wiring errors (always double check before you first switch on).
2.  PCB errors (broken tracks, bridged tracks, errors in the track layout
(less likely) ).
3.  Components having the wrong orientation, i.e. diodes, transistors, ICs
and polarised capacitors inserted the wrong way round.
4.  Dry joints (solder joints that look OK but don't actually make an
electrical connection).
5.  Solder bridges (where you've inadvertently joined two things with a blob
of solder that shouldn't be joined).

To help avoid such problems you should:
1.  Check the PCB for cracks and errors.
2.  Check the PCB for solder bridges.
3.  Always double check all wiring before you first switch on.
4.  Always double check component orientations before you first switch on.
5.  Ensure solder joints are bright and shiny (a dull joint is sometimes a
dry one).
6.  Use sockets for ICs and the more expensive transistors.  This will
greatly aid fault diagnoses and avoid the possibility of overheating
components when soldering.
7.  Handle ESDs (electro-static sensitive devices) correctly.
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