Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Guitars => Topic started by: TerryD on May 25, 2011, 08:04:41 am

Title: Grounding problem on Big (Chinese) Jazz Box
Post by: TerryD on May 25, 2011, 08:04:41 am
I cant figure this out.  When I let go of the strings, plenty of buzzing......But, when I hook up my multimeter to "buzz" when there is a connection (continuity?), I get a buzz when one probe is hooked to the metal tailpiece and all the following spots: output jack, all vol & tone pots, both pick up covers and three way switch.

What could possibly be Wrong????
Title: Re: Grounding problem on Big (Chinese) Jazz Box
Post by: G._Hoffman on May 25, 2011, 04:03:33 pm
I cant figure this out.  When I let go of the strings, plenty of buzzing......But, when I hook up my multimeter to "buzz" when there is a connection (continuity?), I get a buzz when one probe is hooked to the metal tailpiece and all the following spots: output jack, all vol & tone pots, both pick up covers and three way switch.

What could possibly be Wrong????


It doesn't sound like there is anything wrong.  There should be conductivity between the strings/tailpiece and all of those spots, and it is perfectly normal for a guitar to hum a bit when you aren't touching the strings.  Beyond that, it is a matter of how much hum, and for that I would need to see it and hear it.  (In person.  Recordings and photos don't help with this kind of stuff.)


Gabriel
Title: Re: Grounding problem on Big (Chinese) Jazz Box
Post by: P Batty on May 25, 2011, 10:31:52 pm
It's conceivable that there might be a ground loop. The guy who assembled the wiring harness may not have understood what he's doing, or it could be an engineering mistake.  You might have to remove it completely (what fun!) and check it against a proven scheme - and then it still might be OK, like Gabe said. 
Title: Re: Grounding problem on Big (Chinese) Jazz Box
Post by: jjasilli on May 26, 2011, 01:32:25 pm
Not getting the question.  Never mind the "meter induced" buzz, for now.  

1.  Completely unlpug the guitar.  Is there continuity per your meter between each STRING and the guitar's output jack ground?  (It is not necessary to disassemble the guitar for this test.)  If yes, then,

2.  Plug your cable into the guitar; leave the other end of the cable unplugged.  Is there continuity between the strings and the unplugged cable's plug ground?