Hi,

Does anyone have troubleshooting experience with the filter final amp =
section of the PSN circuit?  After 2 1/2 years of operation I began to =
notice strange signals in my records.  Now I can only get a full scale =
reading either + or - with a very small change of the centering 50K pot. =
 I removed the pot thinking it was bad but I can't detect any shorts or =
bad spots over the range of adjustment.  If I remove the OP27 from its =
socket the AD reads a steady 2 and responds properly to various voltages =
applied directly to the output pin of the OP27 socket.  I have the input =
shorted to ground and I have tried removeing the LF 353 with no change.  =
I have also swapped the OP27 with another with the same result.=20








Hi,
 
Does anyone have troubleshooting =
experience with=20
the filter final amp section of the PSN circuit?  After 2 1/2 years =
of=20
operation I began to notice strange signals in my records.  Now I =
can only=20
get a full scale reading either + or - with a very small change of the =
centering=20
50K pot.  I removed the pot thinking it was bad but I can't detect =
any=20
shorts or bad spots over the range of adjustment.  If I remove the =
OP27=20
from its socket the AD reads a steady 2 and responds properly to=20
various voltages applied directly to the output pin of the OP27=20
socket.  I have the input shorted to ground and I have tried =
removeing the=20
LF 353 with no change.  I have also swapped the OP27 with another =
with the=20
same result. 
 
Randy