Jimbob3416
Member
Hello everyone,
I just finished the power supply, power amp and Eq Board on my SX-535. Also replaced the large filter caps. FM is awesome, no distortion as it had when I first fired it up. One problem that is eluding my trouble shooting skills. When I switch to phono I have a very loud hum (nothing connected) and it gets worse when I put my hand close to the pre amp board and input RCA jacks. It gets louder with volume. I have checked all grounds and seem to all be connected. This hum was there when I first powered it up after getting it in the mail. I was hopping that re-capping and replacing all old transistors it would be taken care of. No such luck. I mainly planed to use this for playing records. Haven’t touched the SW & Control board yet. All switches have been cleaned with DeoxIT.
Also I tweeked VR1 & VR2 on the power amp board. The right channel calmed down to 15mv but the left is all over from 25-10mv can’t seem to stabilize it. I’ll let it run for a few hours and try again. These are new Bourns pots. Could I have some suggestions that I could check and try to get rig of this hum.
Thanks everyone.
I just finished the power supply, power amp and Eq Board on my SX-535. Also replaced the large filter caps. FM is awesome, no distortion as it had when I first fired it up. One problem that is eluding my trouble shooting skills. When I switch to phono I have a very loud hum (nothing connected) and it gets worse when I put my hand close to the pre amp board and input RCA jacks. It gets louder with volume. I have checked all grounds and seem to all be connected. This hum was there when I first powered it up after getting it in the mail. I was hopping that re-capping and replacing all old transistors it would be taken care of. No such luck. I mainly planed to use this for playing records. Haven’t touched the SW & Control board yet. All switches have been cleaned with DeoxIT.
Also I tweeked VR1 & VR2 on the power amp board. The right channel calmed down to 15mv but the left is all over from 25-10mv can’t seem to stabilize it. I’ll let it run for a few hours and try again. These are new Bourns pots. Could I have some suggestions that I could check and try to get rig of this hum.
Thanks everyone.
