MS9-29A Green Gain Help

[narf]

got a Nanao MS9-29A that the Green Gain does not work for some reason (no change even with full rotation to stops of G-GAIN pot)

Green cut off on chassis works fine

Green gain seems to be stuck a little above center position and tends to bleed through a little

Note the following has been done to troubleshoot but issue remains:

Hot, large and main joints reflowed on chassis and neck boards

full recap on neck board and chassis

tried spare known good remote board and ribbon cable, still get same issue

even tested G-GAIN pot on multimeter and replaced G-GAIN pot on the remote board to make sure I wasn't going insane. No luck.

Any ideas what / where I should try next?

 

[jcmorrisii]

got a Nanao MS9-29A that the Red Gain does not work for some reason (no change even with full rotation to stops of R-GAIN pot)

Green cut off on chassis works fine

Green gain seems to be stuck a little above center position and tends to bleed through a little

Note the following has been done to troubleshoot but issue remains:

Hot, large and main joints reflowed on chassis and neck boards

full recap on neck board and chassis

tried spare known good remote board and ribbon cable, still get same issue

even tested G-GAIN pot on multimeter and replaced G-GAIN pot on the remote board to make sure I wasn't going insane. No luck.

Any ideas what / where I should try next?

You say the issue with with the Red cutoff but you replaced the Green gain trimmer? Did you mean you replaced the R gain trimmer? Just trying to clarify which one we are looking at, red or green (I know you mentioned bleeding from green too and was in title but wasnt sure). If not, I was going to suggest metering the resistance between leg 1 and 3 on the trimmer to see if its in spec, then legs 1 to 2 to see if it is proper resistance and that your able to trim it effectively (while being metered with DMM turn trimmer all the way each direction, should go from 1ohm to whatever the spec resistance of the trimmer is , check the schematic for the original value). Rare but can fail. But sounds like you may have already ruled that out?

 

[narf]

You say the issue with with the Red cutoff but you replaced the Green gain trimmer? Did you mean you replaced the R gain trimmer? Just trying to clarify which one we are looking at, red or green (I know you mentioned bleeding from green too and was in title but wasnt sure). If not, I was going to suggest metering the resistance between leg 1 and 3 on the trimmer to see if its in spec, then legs 1 to 2 to see if it is proper resistance and that your able to trim it effectively (while being metered with DMM turn trimmer all the way each direction, should go from 1ohm to whatever the spec resistance of the trimmer is , check the schematic for the original value). Rare but can fail. But sounds like you may have already ruled that out?

Hi Sorry my mistake meant to say G-GAIN pot. have edited original post to fix this
as mentioned I did already check the pot on multimeter and its fine. I have also replaced the pot and tested with a spare remote board with same issue. For reference its a 3.3k pot