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Roand JC-77
The following symptoms appear only when
the Chrous switch is set to Chorus OFF.
Crackling, popping,rumbling noise
This noise is not affected by either a
input volume increase (instrutment) or
an increase of the JC-77 volume control.
It is also not affected by any other
control i.e. treble, bass, middle reverb
etc. This noise also modulates from nearly
non existent to annoyingly loud. If the
amp is set out in a cold envoirnment the
noise will not be present until the amp
warms up. Obviously heat related yet the
amp must be at below normal room temperature
to indicate the heat issue.
In other words when the amp is in either
Chorus "Manual" or Chorus "Fixed mode there
is no problem whatsoever. As a matter of
fact this is a very quiet amp other than
this Chorus OFF mode noise. The amp had a
bit of hiss and hum but I went through the
amp and or re-solder every connection
to see if a bad connection was the issue.
Well it was not but it sure made the rest of
the amp quiet when I put it back together.
Cleaning the chorus switch had no impact
on the issue.
I will venture to guess that this issue
has something to do with one of the delay
(Chorus) IC's as the clean signal passes
through it. But to be honest I am not able
to read the schematic to the level that I
can understand the actual path of the clean
signal.
Thanks for you consideration.
The following symptoms appear only when
the Chrous switch is set to Chorus OFF.
Crackling, popping,rumbling noise
This noise is not affected by either a
input volume increase (instrutment) or
an increase of the JC-77 volume control.
It is also not affected by any other
control i.e. treble, bass, middle reverb
etc. This noise also modulates from nearly
non existent to annoyingly loud. If the
amp is set out in a cold envoirnment the
noise will not be present until the amp
warms up. Obviously heat related yet the
amp must be at below normal room temperature
to indicate the heat issue.
In other words when the amp is in either
Chorus "Manual" or Chorus "Fixed mode there
is no problem whatsoever. As a matter of
fact this is a very quiet amp other than
this Chorus OFF mode noise. The amp had a
bit of hiss and hum but I went through the
amp and or re-solder every connection
to see if a bad connection was the issue.
Well it was not but it sure made the rest of
the amp quiet when I put it back together.
Cleaning the chorus switch had no impact
on the issue.
I will venture to guess that this issue
has something to do with one of the delay
(Chorus) IC's as the clean signal passes
through it. But to be honest I am not able
to read the schematic to the level that I
can understand the actual path of the clean
signal.
Thanks for you consideration.