[sdiy] problematic sh101

[Rude 66]

well, no luck so far. i think i can say with a bit of certainty that it
isn't the power supply board, because this seems to be the only thing that's
wedged in firmly. i resoldered the various connections there, and a visual
inspection didn't show anything.
i took the whole synth apart and inspected all the boards by eye and
maginfying glass, resoldering various bits (all right, john,
'reflowing'..;-) especially those involved with the power distribution and
on/off switch. completely removed that sequencer board too. the result? it
stays on a bit longer than before.. but touching it in any way, especially
the now empty sequencer/arpeggio part, and where the 'vco' and 'env' are
written on top of the panel, makes it go on/off. pushing it down a bit on
the left botton and right top corners makes it come on again..

funny thing is, it didn't have this on/off problem when the seqencer board
was in, only when it was laying open. but then, as soon as any of the lights
there came on, it would stop playing.. then pushing on the synth would make
these lights go on and off randomly. grumpf.

diagnosis so far would be that it either is the controller board holding all
the knobs and sliders, since that screws right on to the case where you push
it. and it only takes a light, gentle touch to make it go on/off. or it's
those multicables that connect the 2 boards together, they're white almost
like flatcables in a computer and very stiff. problem with the boards is
also that there's a layer of shiny goop on top of everything (like flux?)
that makes bad traces almost impossible to see.. i'll try dave's
led-solution tomorrow, but i don't have time to spend days on this thing..

thanks for all the tips so far!

r./




----- Original Message -----
From: "Scott Gravenhorst" <music.maker at gte.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, November 06, 2004 6:24 PM
Subject: Re: [sdiy] problematic sh101


> "john mahoney" <jmahoney at gate.net> wrote:
> >> there goes another quiet saturday night..;-)
> >
> >Party on, Rude! ;-)
> >
> >I have a comment on what you said about "before i start on resoldering
> >all connections"...
> >
> >Maybe this isn't what you meant, but you don't have to actually
> >*re*solder them. That is, you don't have to remove the old solder and
> >add new solder. All you've got to do is touch them with a hot iron for
> >a few seconds to melt the existing solder. "Reflow" is the term, I
> >think. This shouldn't take all that long, even for a whole board or
> >two. I mean, yeah, there are a lot of connections, but you can move
> >pretty quickly from one to the next. Could be easier than trying to
> >find that one cracked joint.
>
> This is what I do as well.  Sometimes seeing a crack in solder, even
> with a magnifier, is difficult or impossible, especially if the crack
> is tight around a component lead.
>
> As was mentioned before, I'd start with the power supply and it's
> connections to the various boards.
>
>
>
>
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