Vintage Synth Repair

Hi
 
I have just repaired a Yamaha Clavinova with exactly this fault and the
problem proved to be a broken solder joint on the PCB.  Anytime you have a
fault that can be triggered by thumping the instrument I would always
suspect a faulty solder joint.  Such a problem can be difficult to see.  It
can be narrowed down by gently tapping components with the back of a
screwdriver, not the metal bit, the plastic handle bit.  Alternatively
gently pressing on a component so as to flex the PCB.  All of this while the
unit is powered up.
 
Regards
Brian G3OYU
www.g3oyu.co.uk
 
  _____  

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of scituate_mass
Sent: Tuesday, 10 June 2008 05:32
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Casio CZ-1 output problem
 
Hello. I just purchased a CZ-1 only to discover that it has a very annoying
problem. I was 
only able to try it out with headphones - which emitted a loud, intermittent
crackling sound 
that diminished in frequency (fewer occurrences of the crackling and
steadier output) the 
longer the synth was on. The crackle is accompanied by near loss in volume
of both crackle 
and the intended output signal. I thought at the time that there was
something wrong with 
the headphone output or jack, but when I got home, I discovered that the
exact same thing 
happens via the line out jack. After playing around with the unit, I noticed
that hitting the 
keys hard often triggers a very loud instance of the crackle followed by a
period of non-
crackly, full-volumed output. Has anyone else had this issue? I can imagine
(and I know 
very very little about electronics) that the sound I am hearing is more like
that of a dying 
capacitor or faulty resistor than of a bad jack (I put some Deoxit DL-100 in
the jacks to no 
avail). If anyone can point me in the right direction of some components to
test and possibly 
a schematic to accompany, I would be very thankful.

Thanks in advance!
 



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