Troubleshooting Jazzmaster - no sound on lead circuit?

For help with setups and other technical issues.
Post Reply
User avatar
Ceylon
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 2533
Joined: Sun Jan 02, 2011 8:27 am
Location: Middle of the Baltic Sea

Troubleshooting Jazzmaster - no sound on lead circuit?

Post by Ceylon » Tue Jul 09, 2019 8:46 am

So I'm really crap at soldering and I've switched pickups in my Jazzmaster a couple of times. As a result most of the solder joints are crap. It was working a while ago however, but now the lead circuit is just quiet, no hum, buzz or nothing. The rhythm circuit works fine, however. I tried opening the pickguard and touching all the joints, and it seems like everything directly connected to the rhythm pots work, or at least touching those points causes static. But even the lower two joints on the circuit switch do nothing, and on the output jack only the catch itself and the rhythm ground respond. I figured the ground wire under the vibrato might have shook loose but it seems to be in place. What might be wrong?

Something like coca cola seems to have been spilled on it in the recent past, not by me but if I'd hazard a guess it wouldn't have been left plugged in at the time. Could something have shorted out?
Science Friction burns my fingers
Electricity still lingers

User avatar
timtam
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 1237
Joined: Sun Oct 22, 2017 2:42 am
Location: Melbourne

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by timtam » Tue Jul 09, 2019 6:01 pm

First check the lead/rhythm switch with a multimeter set to continuity to make sure it is actually switching in the lead circuit (one side switching the neck pickup to the toggle switch; the other side switching the main volume pot to the output jack). If yes, then test the toggle switch to see if it is switching everything (neck and bridge pickups) through to the volume pot. Then test the volume and tone pots and the connection back to lead/rhythm switch. Check that all grounds in the lead circuit are continuous with the rim of the output jack (ground) when the lead circuit is switched on. Check that no hots are continuous (shorted) with the jack rim. Follow the wiring ...
https://www.fmicassets.com/Damroot/Orig ... A_SISD.pdf
Timtam (noun): Iconic Australian multi-layered chocolate biscuit.

User avatar
andy_tchp
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 5821
Joined: Fri Apr 02, 2010 1:36 am
Location: Brisbane

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by andy_tchp » Tue Jul 09, 2019 6:58 pm

Are the cavities thoroughly shielded with copper tape, including up the 'walls' of the route?

If so, the output tab from the 3-way switch can easily short to ground via the shielding - there is very little space where it mounts, and when shorted will produce the symptom you describe (dead silence).

IF this is the cause, the symptom will also disappear when using a multimeter to troubleshoot with the pickguard removed from the guitar and flipped over, as this lifts the entire switch away from the shield.
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

User avatar
Ronkirn
PAT PEND
PAT PEND
Posts: 42
Joined: Sun Oct 11, 2009 4:12 pm
Location: in the land of humidity...
Contact:

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by Ronkirn » Sat Jul 20, 2019 5:02 am

"Something like coca cola seems to have been spilled on it in the recent past,"

Humm.. what by some phantom Coke Gremlin? :P

anyway, yes . . .coke is full of acids.. that makes the liquid conductive.... if it got into the components, switches, pots etc... or just across some connections,, that would do it....

try this... first rip an old power supply out of that old Pentium II computer with Windows Me on it..the one ya have in the attic... You'll never use it again. and the contacts in the supply are about the same as though you will find in the JM.. practice, practice, practice. Solder and unsolder the contacts until you can ,make a clean joint... check you tube videos. it should take ya one beer and 15 minutes to master it... it's not rocket science...

Now, dive in the JM and clean ups all those cold joints.. after which, . . . Live long and Prosper.. , Oh Id love to see some photos of the existing electronics in the JM.

Ron Kirn
“It’s easier to fool people than to convince them that they have been fooled.” Mark Twain

User avatar
otis
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 1863
Joined: Fri Sep 18, 2009 10:27 am
Location: Belgium

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by otis » Sun Jul 21, 2019 10:13 am

andy_tchp wrote:
Tue Jul 09, 2019 6:58 pm
Are the cavities thoroughly shielded with copper tape, including up the 'walls' of the route?

If so, the output tab from the 3-way switch can easily short to ground via the shielding - there is very little space where it mounts, and when shorted will produce the symptom you describe (dead silence).

IF this is the cause, the symptom will also disappear when using a multimeter to troubleshoot with the pickguard removed from the guitar and flipped over, as this lifts the entire switch away from the shield.
This is what happened last week to my AVRI Jazzmaster when I changed pickguards.
When I checked visually every solder joint was intact and there were no loose wires.
I put everything back, holding the pots, toggle and input jack in place while tightening their bolts and when I tried it again everything worked.
It's the first time this happened to me, so I was a little confused at first but figured out it must have been the shielding touching a metal part.

User avatar
Ceylon
PAT. # 2.972.923
PAT. # 2.972.923
Posts: 2533
Joined: Sun Jan 02, 2011 8:27 am
Location: Middle of the Baltic Sea

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by Ceylon » Tue Jul 23, 2019 5:11 am

Ronkirn wrote:
Sat Jul 20, 2019 5:02 am
"Something like coca cola seems to have been spilled on it in the recent past,"

Humm.. what by some phantom Coke Gremlin? :P

anyway, yes . . .coke is full of acids.. that makes the liquid conductive.... if it got into the components, switches, pots etc... or just across some connections,, that would do it....
To be completely honest I have no idea when it might have happened. I figure it must have been when I had some people over and we'd had a couple of drinks, because that's the only scenario I can imagine where something would have gotten spilled on it without me registering it. I don't baby my guitars, far from it, but I'm also not neglectful.

The two-way switch IS kind of coming apart though, and while it still obviously switches between the two circuits it should be replaced. So I'm thinking I might go all the way, get a new switch, some cheap cloth wire and an orange drop and just re-wire the thing entirely now that I've a bit more experience under my belt. If it's of any interest I'll take a few picture of the electronics as they look right now. But it is pretty much jury rigged with whatever pieces of wire I had in my box of junk at the time :fp: Though it did work perfectly for a while.

As for shielding, the cavities are painted in shielding paint, but no copper tape. The problem doesn't go away if I lift the pickguard off the body, otherwise that might well have been it.
Science Friction burns my fingers
Electricity still lingers

User avatar
Ronkirn
PAT PEND
PAT PEND
Posts: 42
Joined: Sun Oct 11, 2009 4:12 pm
Location: in the land of humidity...
Contact:

Re: Troubleshooting Jazzmaster - no sound on lead circuit?

Post by Ronkirn » Tue Jul 23, 2019 5:33 am

let's see a few good photos... then I might be able to help.. but. ig you have parts "coming apart".. I'd look right there first..

r
“It’s easier to fool people than to convince them that they have been fooled.” Mark Twain

Post Reply