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Lumberjack88

Member
Joined
Oct 31, 2021
Messages
5
I bought a secondhand Luke III guitar with the two DiMarzio Transition Humbuckers and the preamp boost on the volume pot and, after playing around for just a week, the volume push-push pot seems to be broken. It worked flawlessly before, and now some mechanism seems to be broken so that it can't stay down in the off position. It's always in the on position now. I unscrewed this pot just to see if maybe there wasn't enough room on the down movement, but, even without the pot screwed onto the guitar, the push-push part just won't stay in the down position.

Is the only way to fix this situation to buy a new volume pot? Since this guitar features active circuitry, how difficult would it be to just change that single volume pot? Do I have to simultaneously change other parts in the guitar along with that volume pot? As far as soldering is concerned, I have a 450° Celsius soldering iron and I'm not sure if I'll damage the pot and the active preamp circuitry at that temperature.

BTW: I'm from Switzerland and I can't order one of these pots from the Music Man online store. Hope some EBMM representative can chime in to let me know how I should proceed. I already filled out a customer service contact formular 3 days ago or so but haven't received a response yet.
 

tbonesullivan

Well-known member
Joined
Aug 24, 2012
Messages
2,041
Location
New Jersey
Did you inspect the exterior of the pot inside the control cavity? It's possible that the retaining spring thing has moved out of place.
 

Lumberjack88

Member
Joined
Oct 31, 2021
Messages
5
Did you inspect the exterior of the pot inside the control cavity? It's possible that the retaining spring thing has moved out of place.

Can I see the spring from the outside? So far, I can only see two little holes per side near the main pot. I can insert a zip tie through these holes just to keep the knob in the down position permanently, but I won't ever be able to use the active preamp with this zip tie approach.

Fixing the spring sounds a bit more intriguing if only I could locate it in the first place.
 

Lumberjack88

Member
Joined
Oct 31, 2021
Messages
5
Contact support, the push-pull needs to be replaced and so does the preamp attached to it. It sucks!

Damn, are you sure the preamp needs to be changed too? To me it looks likr there are a few wires from the preamp connected to the volume push push pot, which means that I could just replace the pot and leave everything else be. Maybe they've adjusted and specialised the preamp circuitry so that it only works with the one volume pot that's already in there. I contacted support but have yet to hear an answer...
 

Magic Jason

Well-known member
Joined
Jul 12, 2014
Messages
1,241
Location
Malmedy, Belgium
Mine had to be replaced...

But it was an early model : Olive Gold/rosewood neck. (Which are, still now, the best Luke III ever produced!)

Things might have been updated since then.
 

msquared

Well-known member
Joined
Apr 12, 2020
Messages
45
Location
Lawrence, KS
Damn, are you sure the preamp needs to be changed too? To me it looks likr there are a few wires from the preamp connected to the volume push push pot, which means that I could just replace the pot and leave everything else be. Maybe they've adjusted and specialised the preamp circuitry so that it only works with the one volume pot that's already in there. I contacted support but have yet to hear an answer...
You don't need to replace the preamp, just the potentiometer.

Customer support can help you out but you may need to call them instead of emailing them.
 

Lumberjack88

Member
Joined
Oct 31, 2021
Messages
5
I've replaced the volume pot and I'm not sure if the guitar behaves as it should. I fired up a compressor and looked at how much gain reduction i could achieve with my hard strumming. I achieved around -18 for the bridge pickup, -18 for the neck and -16 for the middle position and both in-between positions were around -20. These measurements are without the preamp activated (volume pot in the down position). Then I kicked in the preamp (volume pot in the up posiition), and I measure -20 in the bridge, -19 in the middle and -20 in the neck positionm the two in-between were both still around -20.

It seems like the preamp boost is always activated for the two in-between positions. Is this normal or should the in-between positions have much less output if the volume pot is down?

The push push pot has that little tower thing built upon the pot with 6 pins (3 on each side) and there I soldered the white wire across the upper two pins and the red wire across the middle two pins horizontally. Is one of those wires faulty so that it causes the preamp boost for the in-between positions to remain active even though the volume pot is in the down position?

Or is one of the three cables from the preamp that connects directly to the three prongs of the pot itself, faulty?
 

beej

Moderator
Joined
Aug 16, 2004
Messages
11,310
Location
Toronto, Canada
The Luke is configured to boost the middle position(s) so that they don't have a drop in volume, like you would on a passive guitar. So from that perspective, they're always going to get a certain amount of boost/compensation. On top of this, you have the boost when the pot is pushed out, giving you extra output.

There are trimpots on the board to adjust both.

This is hard to diagnose remotely- if you think something isn't right, drop the customer service team a line and let them help you out.
 
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