Vintage Synth Repair

Hi,

I recently purchased a Moog Source from the US, which I now got 
rewired for 240V(thanks to Peter M. Blacket for the schematics!). To 
my relief the membrane switch panel seems to be intact, but there's 
another annoying problem: 

When I turn it on it's working fine for about 10-15 minutes, 
suddenly the keyboard goes crazy. It keeps playing the wrong notes 
from the wrong keys, and sometimes it can re-trigger the envelopes 
several times while pressing a key. Funnily this doesn't seem to 
affect the lowest octave. Sometimes it may start to work properly 
again after a couple of minutes. 

I wonder if this has something to do with the power supply 
generating heat, after a while it gets so hot that i almost burn my 
fingers on the back panel.

Please reply if anybody has a clue what may be the cause(and cure) 
of this problem. Somehow I got the feeling this is not the 
famous "crazy source" syndrome, since it looks like the previous 
owner did something to the digital regulators on the PSU board.

Thanks in advance,
Einar Ekstrom

--- In vintagesynthrepair@y..., "einarekstrom" <einarekstrom@y...> 
wrote:
> Hi,
> 
> I recently purchased a Moog Source from the US, which I now got 
> rewired for 240V(thanks to Peter M. Blacket for the schematics!). 
To 

> my relief the membrane switch panel seems to be intact, but there's 
> another annoying problem: 
> 
> When I turn it on it's working fine for about 10-15 minutes, 
> suddenly the keyboard goes crazy. It keeps playing the wrong notes 
> from the wrong keys, and sometimes it can re-trigger the envelopes 
> several times while pressing a key. Funnily this doesn't seem to 
> affect the lowest octave. Sometimes it may start to work properly 
> again after a couple of minutes. 
> 
> I wonder if this has something to do with the power supply 
> generating heat, after a while it gets so hot that i almost burn my 
> fingers on the back panel.
> 
> Please reply if anybody has a clue what may be the cause(and cure) 
> of this problem. Somehow I got the feeling this is not the 
> famous "crazy source" syndrome, since it looks like the previous 
> owner did something to the digital regulators on the PSU board.
> 
> Thanks in advance,
> Einar Ekstrom

Hi "Kanaguvnor",

It seems you tried to reply to my post, but your reply only contained
 my original message, strange...
Well, Kanaguvnor (or anyone else for that matter), please try to reply
again if you had some thoughts of the subject.

Einar




--- In vintagesynthrepair@y..., "kanaguvnor" <guvnor@r...> wrote:

> --- In vintagesynthrepair@y..., "einarekstrom" <einarekstrom@y...> 
> wrote:
> > Hi,
> > 
> > I recently purchased a Moog Source from the US, which I now got 
> > rewired for 240V(thanks to Peter M. Blacket for the schematics!). 
> To 
> > my relief the membrane switch panel seems to be intact, but there's 
> > another annoying problem: 
> > 
> > When I turn it on it's working fine for about 10-15 minutes, 
> > suddenly the keyboard goes crazy. It keeps playing the wrong notes 
> > from the wrong keys, and sometimes it can re-trigger the envelopes 
> > several times while pressing a key. Funnily this doesn't seem to 
> > affect the lowest octave. Sometimes it may start to work properly 
> > again after a couple of minutes. 
> > 
> > I wonder if this has something to do with the power supply 
> > generating heat, after a while it gets so hot that i almost burn my 
> > fingers on the back panel.
> > 
> > Please reply if anybody has a clue what may be the cause(and cure) 
> > of this problem. Somehow I got the feeling this is not the 
> > famous "crazy source" syndrome, since it looks like the previous 
> > owner did something to the digital regulators on the PSU board.
> > 
> > Thanks in advance,
> > Einar Ekstrom

OK. Lets Try this again ;)

I dug this one up from one of the newsgroups quite a while ago that 
may be of use:

"

The cause of the "Crazy Source" problem seems to be the following:
- The power supply board is attached to the top control surface.
- The voltage regulators are mounted to the back wall of the synth.
- The sockets connecting these voltage regulators to the power supply 
  board are at located the "hinge point".

Every time the control surface is pressed, it moves the power supply 
board. Since the regulator pins and sockets corrode over time, this 
movement causes intermittent fluctuations in load resistance thus 
causing voltage drops. This inturn causes grief for the CPU and logic 
circuitry.

Note: Moog had issued technical bulletins on how to resolve this 
problem through the use of special plastic regulator holders however 
these parts are not necessary.

The easy way to repair the problem is to essentially desolder and 
remove the troublesome sockets and "extend" the voltage regulator 
leads through the now empty socket's through-holes.  Resistor leads 
or 20 to 22 awg wire make great "extensions".

Simply push the "extensions" through the pc board's through-holes and 
solder these to the legs of the corresponding regulators. Since the 
regulators are attached to the big aluminum block, soldering is easy 
and there is no need to remove the regulators. 

Steps:

1.  Open synth. (with power off and UNPLUGGED!!)

2.  Unplug all connectors to the power supply board (note their 
position and orientation)

3.  Remove two screws holding the power supply board to synth's 
control surface

4.  Remove two screws holding the power supply board and aluminum 
heat sink assembly to the synth's back panel

5.  Remove the power supply board and aluminum heat sink assembly 
from the synth (watch out for the messy heat sink compound!!)

6.  Desolder all regulator sockets.

7.  Unscrew two screws holding the power supply board to aluminum 
heat sink.

8.  Remove the regulator sockets from the power supply circuit board.

9.  Reassemble the power supply board and aluminum heat sink assembly.

10. Push wire or lead through each of the socket's through-holes and 
solder to the voltage regulator leads. Do one at a time. Don't solder 
leads to circuit board yet.

11. When all leads are soldered, inspect for poor joints, shorts, 
solder balls and solder bridges.

12. Solder "extended" leads to circuit board solder pads.

13. When all leads are soldered, inspect for poor joints, shorts and 
solder bridges.

13. Install the power supply board assembly in the synth then 
reassemble synth.

Note: The aluminum heat sink has lots of heat sink paste on it. This 
is very messy stuff.  You may wish to put wax paper or a plastic bag 
on the work surface.

If you get mixed up with the connectors P-13...P-16 They are labeled. 
Simply match the label to the silk screened text on the circuit 
board. All edge black wires for each connector are on the right hand 
side. (Missing pins on the sockect match missing wires on the 
connector)

"


Hope this helps!!!

Guvnor




--- In vintagesynthrepair@y..., "einarekstrom" <einarekstrom@y...> 
wrote:
> Hi "Kanaguvnor",
> 
> It seems you tried to reply to my post, but your reply only 
contained
>  my original message, strange...
> Well, Kanaguvnor (or anyone else for that matter), please try to 
reply
> again if you had some thoughts of the subject.
> 
> Einar
> 
> 
> 
> 
> --- In vintagesynthrepair@y..., "kanaguvnor" <guvnor@r...> wrote:
> > --- In vintagesynthrepair@y..., "einarekstrom" 
<einarekstrom@y...> 
> > wrote:
> > > Hi,
> > > 
> > > I recently purchased a Moog Source from the US, which I now got 
> > > rewired for 240V(thanks to Peter M. Blacket for the 
schematics!). 
> > To 
> > > my relief the membrane switch panel seems to be intact, but 
there's 
> > > another annoying problem: 
> > > 
> > > When I turn it on it's working fine for about 10-15 minutes, 
> > > suddenly the keyboard goes crazy. It keeps playing the wrong 
notes 
> > > from the wrong keys, and sometimes it can re-trigger the 
envelopes 
> > > several times while pressing a key. Funnily this doesn't seem 
to 
> > > affect the lowest octave. Sometimes it may start to work 
properly 
> > > again after a couple of minutes. 
> > > 
> > > I wonder if this has something to do with the power supply 
> > > generating heat, after a while it gets so hot that i almost 
burn my 
> > > fingers on the back panel.
> > > 
> > > Please reply if anybody has a clue what may be the cause(and 
cure) 
> > > of this problem. Somehow I got the feeling this is not the 
> > > famous "crazy source" syndrome, since it looks like the 
previous 

> > > owner did something to the digital regulators on the PSU board.
> > > 
> > > Thanks in advance,
> > > Einar Ekstrom

--- In vintagesynthrepair@y..., "kanaguvnor" <guvnor@r...> wrote:

> The easy way to repair the problem is to essentially desolder and 
> remove the troublesome sockets and "extend" the voltage regulator 
> leads through the now empty socket's through-holes.  Resistor leads 
> or 20 to 22 awg wire make great "extensions".
 


Thanks Guvnor,

One question, is this to be done on ALL 3 (or was it 4) voltage
regulators? When I opened up the synth I could see that this
convertion has been done by the previous owner to only ONE of the
regulators.

Anyway, I'm not totally convinced this is a "Crazy Source" problem.
Yesterday when I was playing with the synth i realised that the
problem is probably not caused by the heat of the PSU, instead I think
it's caused by vibrations. When I hold down a key and give the synth a
bang in the side panel it usually changes the pitch by a semitone or two. 
Further investigation proved that when a note shift occurs, it shifts
all notes of the two highest octaves equally much. The lowest octave
seem to be unaffected by the problem. 
Somehow I think the problem could be in the keyboard itself, a bad
connection, dirty contacts or something.

Well, I'll try to clean all the contacts(again!) and check for bad
connections. I'll return for help if the problem prevails.

Oh, one more thing. Is the powersupply really supposed to become so
hot that I burn my fingers on the back panel??  

Thanks,
Einar

You can pretty much fry an egg on the back of my Source...

--- In vintagesynthrepair@y..., "einarekstrom" <einarekstrom@y...> 
wrote:
> --- In vintagesynthrepair@y..., "kanaguvnor" <guvnor@r...> wrote:
> 
> > The easy way to repair the problem is to essentially desolder and 
> > remove the troublesome sockets and "extend" the voltage regulator 
> > leads through the now empty socket's through-holes.  Resistor 
leads 
> > or 20 to 22 awg wire make great "extensions".
>  
> 
> 
> Thanks Guvnor,
> 
> One question, is this to be done on ALL 3 (or was it 4) voltage
> regulators? When I opened up the synth I could see that this
> convertion has been done by the previous owner to only ONE of the
> regulators.
> 
> Anyway, I'm not totally convinced this is a "Crazy Source" problem.
> Yesterday when I was playing with the synth i realised that the
> problem is probably not caused by the heat of the PSU, instead I 
think
> it's caused by vibrations. When I hold down a key and give the 
synth a
> bang in the side panel it usually changes the pitch by a semitone 
or two. 
> Further investigation proved that when a note shift occurs, it 
shifts

> all notes of the two highest octaves equally much. The lowest octave
> seem to be unaffected by the problem. 
> Somehow I think the problem could be in the keyboard itself, a bad
> connection, dirty contacts or something.
> 
> Well, I'll try to clean all the contacts(again!) and check for bad
> connections. I'll return for help if the problem prevails.
> 
> Oh, one more thing. Is the powersupply really supposed to become so
> hot that I burn my fingers on the back panel??  
> 
> Thanks,
> Einar