Buzzing in yamaha JX50

[kd7ura]

I just got an older amp it has a buzz when the cord is pluged in the high or low inputs.
the buzz goes away when i tuch the knobs or strings on the guitar andor when i touch one of the chassie bolts on the case.
could this be a bad cap , or somthing from the power supply leaking trough?
ive pulle the board out cleaned it and replaced to make sure there is a good ground ay all connections, still there.

any help please

[kd7ura]

Ive got a schematic for it now, used circuit board cleaner to clean every thing and lubed the knobs, it has a bit less noise, but the buzz is still there,
it changes with volum on the master and the gain. if i turn the high EQ knob all the way down its gone.
its also completely quiet with no guitar cord pluged in with volum and gain turned all up it has a light shush noise, im assuming its normal circuit noise.
if i plug a cord in with or without a guitar pluged it hums\ buzzes.
the cord is brand new , i tried others same buzz. if i make contact with the chassie it gets a bit quieter but still there and annoyingly loud.
any body have any ideas on what it could be??

[khjodat]

Yamaha guitar amp JX-50

I just got an older amp it has a buzz when the cord is pluged in the high or low inputs.
the buzz goes away when i tuch the knobs or strings on the guitar andor when i touch one of the chassie bolts on the case.
could this be a bad cap , or somthing from the power supply leaking trough?
ive pulle the board out cleaned it and replaced to make sure there is a good ground ay all connections, still there.

any help please

Hi dude I also own this amp. I first got it in 1981 in brand new condition. It was imported from Japan and therefore its power supply was on 110 volts. It has the same problem which you have told. If your amp is also works with a step down transformer from 220 to 110 volts then you can fix the electric shock problem by simply changing the polarity of transformer by turning over its power plug in the power socket. I hope that will help you fixing your problem. Well as far as your guitar or amp buzzing problem this can be a problem with your guitar. For that you need to replace the capacitor attached with the volume or tone pot and moreover you better use a good quality guitar cable/lead. Take care & regards. Khawaja Jodat from Pakistan.