Re: [AH] Fwd: Moog Voyager elusive problem, asking for your advice

From System 100
Sent Fri, May 10th 2013, 14:50

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Yes, I do synth repairs. The problem with finding a cold solder joint is
that there are way too many parts to resolder...
I can try starting with the power supply first. Somehow I have the feeling
that it starts there... but not sure (I know these chinese PS from other
product which have failed more than once). It there any trick finding a
cold solder without resoldering a suspicious area ? when I tap the
components I can't recreate the problem, it just comes and goes.

How do I check for it's correct operation, other than just monitoring the
output DC voltages ? I have a friend who is an engineer so I can use his
help monitoring it...

Thanks!


2013/5/10 cheater00 . <cheater00@gmail.com>

> sounds like a cold solder. are you a tech?
> try disconnecting the power supply and connect a soupy linear bench
> power supply.
>
> try to trigger the bug while observing the voltage rails on the scope
> with the original psu.
>
> On Fri, May 10, 2013 at 2:11 PM, System 100 <system100m@gmail.com> wrote:
> > Hi all !
> >
> > I bought a second hand Voyager a while ago and just found it has a severe
> > issue... Once I power it on, after a few minutes the overall pitch can
> > change dramatically and intermittently for a fraction of a moment and
> than
> > return to normal. I can happen after a few minutes or after half an hours
> > after powering it, and it can come and go spontaneously. It can be heard
> > when using MIDI or the keyboard, and it happens also when the pitch
> wheel is
> > disabled.
> >
> > Please take a look at this video, of an RME acting exactly the same as
> mine:
> >
> > http://www.youtube.com/watch?v=Ew5DQXc-xko
> >
> > The guy there says it was sent to moog for repair a few times and it
> still
> > acts the same... Can anyone think of any idea what causes it ?
> >
> > The voltages are stable and when the pitch changes no change in the main
> > voltages is observed. All connectors and ICs are tightened in place...
> All
> > functions performs well and all pots are in good contact...
> >
> > The only irregular thing I notices was that the 4 transistors on the
> small
> > powersupply board (not the main PS board) are very (very) hot. No
> heatsink
> > was built around them, just thought one of them might have gone bad but
> > again, all voltages are pretty accurate.
> >
> > Will appreciate any help.
>

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<div dir=3D"rtl"><div dir=3D"ltr">Yes, I do synth repairs. The problem with=
 finding a cold solder joint is that there are way too many parts to resold=
er...<br></div><div dir=3D"ltr">I can try starting with the power supply fi=
rst. Somehow I have the feeling that it starts there... but not sure (I kno=
w these chinese PS from other product which have failed more than once). It=
 there any trick finding a cold solder without resoldering a suspicious are=
a ? when I tap the components I can&#39;t recreate the problem, it just com=
es and goes.<br>
<br></div><div dir=3D"ltr">How do I check for it&#39;s correct operation, o=
ther than just monitoring the output DC voltages ? I have a friend who is a=
n engineer so I can use his help monitoring it...<br><br>Thanks!<br></div>
</div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote"><div di=
r=3D"ltr">2013/5/10 cheater00 . <span dir=3D"ltr">&lt;<a href=3D"mailto:che=
ater00@gmail.com" target=3D"_blank">cheater00@gmail.com</a>&gt;</span></div=
><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1=
px #ccc solid;padding-left:1ex">
sounds like a cold solder. are you a tech?<br>
try disconnecting the power supply and connect a soupy linear bench<br>
power supply.<br>
<br>
try to trigger the bug while observing the voltage rails on the scope<br>
with the original psu.<br>
<div class=3D"HOEnZb"><div class=3D"h5"><br>
On Fri, May 10, 2013 at 2:11 PM, System 100 &lt;<a href=3D"mailto:system100=
m@gmail.com">system100m@gmail.com</a>&gt; wrote:<br>
&gt; Hi all !<br>
&gt;<br>
&gt; I bought a second hand Voyager a while ago and just found it has a sev=
ere<br>
&gt; issue... Once I power it on, after a few minutes the overall pitch can=
<br>
&gt; change dramatically and intermittently for a fraction of a moment and =
than<br>
&gt; return to normal. I can happen after a few minutes or after half an ho=
urs<br>
&gt; after powering it, and it can come and go spontaneously. It can be hea=
rd<br>
&gt; when using MIDI or the keyboard, and it happens also when the pitch wh=
eel is<br>
&gt; disabled.<br>
&gt;<br>
&gt; Please take a look at this video, of an RME acting exactly the same as=
 mine:<br>
&gt;<br>
&gt; <a href=3D"http://www.youtube.com/watch?v=3DEw5DQXc-xko" target=3D"_bl=
ank">http://www.youtube.com/watch?v=3DEw5DQXc-xko</a><br>
&gt;<br>
&gt; The guy there says it was sent to moog for repair a few times and it s=
till<br>
&gt; acts the same... Can anyone think of any idea what causes it ?<br>
&gt;<br>
&gt; The voltages are stable and when the pitch changes no change in the ma=
in<br>
&gt; voltages is observed. All connectors and ICs are tightened in place...=
 All<br>
&gt; functions performs well and all pots are in good contact...<br>
&gt;<br>
&gt; The only irregular thing I notices was that the 4 transistors on the s=
mall<br>
&gt; powersupply board (not the main PS board) are very (very) hot. No heat=
sink<br>
&gt; was built around them, just thought one of them might have gone bad bu=
t<br>
&gt; again, all voltages are pretty accurate.<br>
&gt;<br>
&gt; Will appreciate any help.<br>
</div></div></blockquote></div><br></div>

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