Vintage Synth Repair

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
>