I am posting this for fellow Cort Curbow owners,
should they encounter this problem - and save them
some grief!
My adorable fretless CC developed a strange problem...
The volume would fade down, and a tweak of the
volume pot would bring it crackling back to "loud".
"Hmmm, dirty pot" I thought, so I cleaned it with
Cramolin Pot Cleaner...Soon after the problem
happened again - volume faded, and a tiny tweak
of the vol pot came crackling back. So, I ordered
a replacement 25k A taper mini pot! After it was installed
I was jamming with my regulars when - once AGAIN
the volume faded down, to return with a tweak of the
volume pot
Being an electrotech guy for a living, I checked the
pot to see if DC was showing up there from the preamp
ckt - hmmm none... But....After waiting it out and
leaving it on for a while on my bench, the volume
faded, and I looked at the input leg of the pot
from the preamp - there was a 3 megahertz oscillation
!
Turns out the FET front ended IC they use in this
preamp (four of them) - the final output op amp
had become unstable (as FETs can do - ) Cort uses
a TL062 surface mount package, which can be
sub' d by many other similar chips. They use that one
for its middling noise level, but super low current drain.
If you don't mind getting somewhat less battery life
you can change these out for the quieter TL072
or the very nice TLE2072.
So sometimes "a dirty pot" is not just a dirty pot!
should they encounter this problem - and save them
some grief!
My adorable fretless CC developed a strange problem...
The volume would fade down, and a tweak of the
volume pot would bring it crackling back to "loud".
"Hmmm, dirty pot" I thought, so I cleaned it with
Cramolin Pot Cleaner...Soon after the problem
happened again - volume faded, and a tiny tweak
of the vol pot came crackling back. So, I ordered
a replacement 25k A taper mini pot! After it was installed
I was jamming with my regulars when - once AGAIN
the volume faded down, to return with a tweak of the
volume pot
Being an electrotech guy for a living, I checked the
pot to see if DC was showing up there from the preamp
ckt - hmmm none... But....After waiting it out and
leaving it on for a while on my bench, the volume
faded, and I looked at the input leg of the pot
from the preamp - there was a 3 megahertz oscillation
!
Turns out the FET front ended IC they use in this
preamp (four of them) - the final output op amp
had become unstable (as FETs can do - ) Cort uses
a TL062 surface mount package, which can be
sub' d by many other similar chips. They use that one
for its middling noise level, but super low current drain.
If you don't mind getting somewhat less battery life
you can change these out for the quieter TL072
or the very nice TLE2072.
So sometimes "a dirty pot" is not just a dirty pot!
