Vintage Synth Repair

howdy folks:
longtime Juno 106 user (first keyboard i ever bought in 1984 - still use the same one). i use 
the keyboard on stage a lot and i've been experiencing something new that i can't say is 
enjoyable:
basically, in the middle of playing, the synth will turn itself off, most  of the lights 
("save/load/write" included) will blink on unison for about 3 seconds, and then the keyboard 
will usually remain off until i turn the power switch off and on again... sometimes this won't 
turn the keyboard back on again and waiting time is required - not the greatest thing in the 
middle of a song on stage!
has anyone else experience this before? anybody heard of this? any suggestions on how to fix 
it?
any help would be greatly appreciated,
thank you
-Jamie

Jamie,

I just repaired a Roland A-90 MIDI controller with a similar problem.
 Unit would shut off and restart without warning.  Sometimes I had to
power off/on to recover.

Check the soldering connections on the power supply circuit board of
the Juno 106.  The PS board on the A90 had bad (cold) solder joints
near the linear voltage regulators (black 'transistor' with 3 leads).
The heat generated by the regulators appears to have weakened the
solder and made it brittle - giving intermittent conductivity.

All I had to do was reheat the connections, apply some more solder and
the problem was fixed.  I also applied some heat sink 'grease' (zinc
oxide + silicone) to the devices to better conduct the heat into the
heat sink.  Available at any Radio Shack.

Others reported similar PS problems with Roland A90 controllers.

It may apply to your Juno 106 also, if the power supply design is similar.

Best regards,

Mike

--- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
<jamie@...> wrote:
>
> howdy folks:
> longtime Juno 106 user (first keyboard i ever bought in 1984 - still
use the same one). i use 
> the keyboard on stage a lot and i've been experiencing something new
that i can't say is 
> enjoyable:
> basically, in the middle of playing, the synth will turn itself off,
most  of the lights 
> ("save/load/write" included) will blink on unison for about 3
seconds, and then the keyboard 
> will usually remain off until i turn the power switch off and on
again... sometimes this won't 
> turn the keyboard back on again and waiting time is required - not
the greatest thing in the 
> middle of a song on stage!
> has anyone else experience this before? anybody heard of this? any
suggestions on how to fix 

> it?
> any help would be greatly appreciated,
> thank you
> -Jamie
>

jamie,
mike's advice is good- this is the same problem that caused the
infamous "insane" behaviour in early/unmodified moog source units; in
that case, the series regs were not soldered at all, but sat loosely
in a connector. removing this & soldering them in place would cure the
moog but meant exercising extra care when removing the case for other
surgery.
it's possible you may have CPU problems though- I have had a 106 in
bits that lost it's mind after "liquid ingress"; the board around the
CPU is quite sensitive & it may just need a clean to remove something
that's deposited there & is "C-shunting" across some CPU connections;
anything that can be carried in the air can settle on a pcb & cause
this, especially if there's dry-ice or smoke involved... :-)

duncan.

thank you mike and duncan...
i indeed had the problem of "crap on my CPU" (to use a technical term) thanks to an 
overzealous confetti operator at a new year's show at hammerstein ballroom a couple 
years back. i thought i had cleaned it all out. maybe i hadn't... i will recheck the options 
you guys have given me.
-J

--- In vintagesynthrepair@yahoogroups.com, "duncan" <ferrograph@...> wrote:

>
> jamie,
> mike's advice is good- this is the same problem that caused the
> infamous "insane" behaviour in early/unmodified moog source units; in
> that case, the series regs were not soldered at all, but sat loosely
> in a connector. removing this & soldering them in place would cure the
> moog but meant exercising extra care when removing the case for other
> surgery.
> it's possible you may have CPU problems though- I have had a 106 in
> bits that lost it's mind after "liquid ingress"; the board around the
> CPU is quite sensitive & it may just need a clean to remove something
> that's deposited there & is "C-shunting" across some CPU connections;
> anything that can be carried in the air can settle on a pcb & cause
> this, especially if there's dry-ice or smoke involved... :-)
> 
> duncan.
>

Hi, if you decide you want to replace the whole CPU board with a
working one, I have one.

Doug
www.synthparts.com

--- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
<jamie@...> wrote:
>
> thank you mike and duncan...
> i indeed had the problem of "crap on my CPU" (to use a technical
term) thanks to an 
> overzealous confetti operator at a new year's show at hammerstein
ballroom a couple 
> years back. i thought i had cleaned it all out. maybe i hadn't... i
will recheck the options 

> you guys have given me.
> -J
> 
> --- In vintagesynthrepair@yahoogroups.com, "duncan" <ferrograph@> wrote:
> >
> > jamie,
> > mike's advice is good- this is the same problem that caused the
> > infamous "insane" behaviour in early/unmodified moog source units; in
> > that case, the series regs were not soldered at all, but sat loosely
> > in a connector. removing this & soldering them in place would cure the
> > moog but meant exercising extra care when removing the case for other
> > surgery.
> > it's possible you may have CPU problems though- I have had a 106 in
> > bits that lost it's mind after "liquid ingress"; the board around the
> > CPU is quite sensitive & it may just need a clean to remove something
> > that's deposited there & is "C-shunting" across some CPU connections;
> > anything that can be carried in the air can settle on a pcb & cause
> > this, especially if there's dry-ice or smoke involved... :-)
> > 
> > duncan.
> >
>

thanks, that's great to know.
-J

--- In vintagesynthrepair@yahoogroups.com, "synthparts" <synthparts@...> wrote:

>
> Hi, if you decide you want to replace the whole CPU board with a
> working one, I have one.
> 
> Doug
> www.synthparts.com
> 
> --- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
> <jamie@> wrote:
> >
> > thank you mike and duncan...
> > i indeed had the problem of "crap on my CPU" (to use a technical
> term) thanks to an 
> > overzealous confetti operator at a new year's show at hammerstein
> ballroom a couple 
> > years back. i thought i had cleaned it all out. maybe i hadn't... i
> will recheck the options 
> > you guys have given me.
> > -J
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "duncan" <ferrograph@> wrote:
> > >
> > > jamie,
> > > mike's advice is good- this is the same problem that caused the
> > > infamous "insane" behaviour in early/unmodified moog source units; in
> > > that case, the series regs were not soldered at all, but sat loosely
> > > in a connector. removing this & soldering them in place would cure the
> > > moog but meant exercising extra care when removing the case for other
> > > surgery.
> > > it's possible you may have CPU problems though- I have had a 106 in
> > > bits that lost it's mind after "liquid ingress"; the board around the
> > > CPU is quite sensitive & it may just need a clean to remove something
> > > that's deposited there & is "C-shunting" across some CPU connections;
> > > anything that can be carried in the air can settle on a pcb & cause
> > > this, especially if there's dry-ice or smoke involved... :-)
> > > 
> > > duncan.
> > >
> >
>

hey doug:
looks like i'm interested in that CPU board after all. my board is exhibiting signs of 
complete cpu breakdown... losing certain voices (only temporarily), certain keys are 
quieter than others, extremely resonant sounds (even with the res turned off), weird pitch 
anomalies, 
let me know what i need to do to get that board from you as quickly as possible. i have to 
install it before my next tour... i am reachable at jamieshields (at) rogers (dot) com
thank you,
-J

--- In vintagesynthrepair@yahoogroups.com, "synthparts" <synthparts@...> wrote:

>
> Hi, if you decide you want to replace the whole CPU board with a
> working one, I have one.
> 
> Doug
> www.synthparts.com
> 
> --- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
> <jamie@> wrote:
> >
> > thank you mike and duncan...
> > i indeed had the problem of "crap on my CPU" (to use a technical
> term) thanks to an 
> > overzealous confetti operator at a new year's show at hammerstein
> ballroom a couple 
> > years back. i thought i had cleaned it all out. maybe i hadn't... i
> will recheck the options 
> > you guys have given me.
> > -J
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "duncan" <ferrograph@> wrote:
> > >
> > > jamie,
> > > mike's advice is good- this is the same problem that caused the
> > > infamous "insane" behaviour in early/unmodified moog source units; in
> > > that case, the series regs were not soldered at all, but sat loosely
> > > in a connector. removing this & soldering them in place would cure the
> > > moog but meant exercising extra care when removing the case for other
> > > surgery.
> > > it's possible you may have CPU problems though- I have had a 106 in
> > > bits that lost it's mind after "liquid ingress"; the board around the
> > > CPU is quite sensitive & it may just need a clean to remove something
> > > that's deposited there & is "C-shunting" across some CPU connections;
> > > anything that can be carried in the air can settle on a pcb & cause
> > > this, especially if there's dry-ice or smoke involved... :-)
> > > 
> > > duncan.
> > >
> >
>

Hi, while I could sell you a CPU board all those probs you mentioned
are most likely due to bad 80017A VCF/VCA voice chips. :(

--- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
<jamie@...> wrote:
>
> hey doug:
> looks like i'm interested in that CPU board after all. my board is
exhibiting signs of 
> complete cpu breakdown... losing certain voices (only temporarily),
certain keys are 
> quieter than others, extremely resonant sounds (even with the res
turned off), weird pitch 
> anomalies, 
> let me know what i need to do to get that board from you as quickly
as possible. i have to 
> install it before my next tour... i am reachable at jamieshields
(at) rogers (dot) com
> thank you,
> -J
> 
> --- In vintagesynthrepair@yahoogroups.com, "synthparts"
<synthparts@> wrote:
> >
> > Hi, if you decide you want to replace the whole CPU board with a
> > working one, I have one.
> > 
> > Doug
> > www.synthparts.com
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "jamesguitar2000"
> > <jamie@> wrote:
> > >
> > > thank you mike and duncan...
> > > i indeed had the problem of "crap on my CPU" (to use a technical
> > term) thanks to an 
> > > overzealous confetti operator at a new year's show at hammerstein
> > ballroom a couple 
> > > years back. i thought i had cleaned it all out. maybe i hadn't... i
> > will recheck the options 
> > > you guys have given me.
> > > -J
> > > 
> > > --- In vintagesynthrepair@yahoogroups.com, "duncan"
<ferrograph@> wrote:
> > > >
> > > > jamie,
> > > > mike's advice is good- this is the same problem that caused the
> > > > infamous "insane" behaviour in early/unmodified moog source
units; in
> > > > that case, the series regs were not soldered at all, but sat
loosely
> > > > in a connector. removing this & soldering them in place would
cure the
> > > > moog but meant exercising extra care when removing the case
for other
> > > > surgery.
> > > > it's possible you may have CPU problems though- I have had a
106 in
> > > > bits that lost it's mind after "liquid ingress"; the board
around the
> > > > CPU is quite sensitive & it may just need a clean to remove
something
> > > > that's deposited there & is "C-shunting" across some CPU
connections;
> > > > anything that can be carried in the air can settle on a pcb &
cause

> > > > this, especially if there's dry-ice or smoke involved... :-)
> > > > 
> > > > duncan.
> > > >
> > >
> >
>

I just had a kurzweil with most of the keys out.
Turned out that I had to resolder most of the leads on the uProcessor and the peripheral ICs
All better now.
Get a tech to try that before you buy a processor board.

Scott  Frye
AudioFixation
Consumer / Pro Audio Repair
Southern VT 

"Resistance is futile but.....
Impedance is much more complex"