Cannot solve 4th string tuning issue.

[Arthur Baker]

About two weeks ago I noticed a tuning issue on my Mullen Royal Precision.
Here is the most succinct explanation of my problem.

When tuning the 4th string knee levers, the lever I tune last does not return to pitch.
For example if I tune the E lever, then the F lever. The F lever returns sharp. In fact it returns sharp immediately, even after starting to tune it very slightly.

The same thing happens if I tune F first, except that it begins to return flat right after starting to tune the E lever down to Eb.

I have checked for overtuning and followed the great instructions on the pinned post about overtuning. I increased the travel on both the levers quite a bit, and raised rods on the bell cranks wherever possible.

When investigating this issue I also checked the return springs and I noticed that when engaging the C pedal, the lower fingers engage slightly on strings 4 and 5. I understand this is an issue, but adjusting spring tension either direction did not fix this. I am pretty sure this is related to the levers not returning to pitch.

Then I increased the travel on the C pedal, no change.

I'm out of ideas now and wondering if anyone here with more knowledge on the subject could weight in with some suggestions of what to try?

[Dennis Detweiler]

4th string...it sounds like maybe the raise helper spring could be the problem, if your guitar has helper springs on the raises? They are narrower springs close to the body of the guitar. Take the 4th helper spring off and see if that solves it (not the larger return springs). Try this first.
If that doesn't solve the problem, check for split tuners at the end of the changer on top of the guitar. They are usually an allan wrench adjustment screw. Some guitars have them on only a few strings and other guitars have a whole row of them. Back the 4th and 5th string split adjustment screws out a turn or two and see if that solves it.

[Arthur Baker]

Thank you for your input Dennis,

I had not considered the raise helper springs being an issue. I removed the 4th string raise helper spring and that did not help the issue unfortunately.

I tried finding the split tuning screws on my guitar and could not find them, turns out the Mullen RP uses a different mechanism for half stops, no screws involved.

[Dennis Detweiler]

Does it have a compensator on the 4th string. If so, it may have been mistaken for a pedal pull rod and tightened too much? If there are two pull rods on the 4th string lower, one is likely a compensator and the other is for tuning the Eb note. Or, instead of a rod, there would be an adjusting screw at the endplate. I'm trying to think of all possibilities. I don't know if Mullen has compensators on their guitars. Zum guitars had compensators on strings 4 and 8.

[Arthur Baker]

Nope, only one pull rod on both the Eb and F levers.

[richard burton]

Maybe the knee lever cross shafts are too tight/binding
Check that there is a little movement end-to-end

[Dennis Detweiler]

There has to be a simple solution? tolerance adjustment as Richard suggested? Use a pen light to look down into the changer and make sure there isn't an obstruction like a string end from a previous broken string? Look at it from the top and bottom. Turn it upside down on a padded table and work those two knee levers back and forth while examining the moving parts. Back the tuning nuts out on the 4th string raise and 4th string lower and re-tune starting with the F lever first. Then make sure there is some slack back and forth on those two rods after it's tuned. If no slack on one of those two rods, you have to re-adjust the stop counter-clockwise on the 4th string to allow some slack (play) back and forth. What string guage are you using on the 4th? It's usually a .014

[Chris Templeton]

This has always been a problem. Compensators should be the solution.

[Jim Palenscar]

Check and see that everything that works w the 4th string (ie- E-D# lever, E-F lever and C pedal all have free play ie- the cross shafts of each change move a bit b4 engaging- and that the 4th string return spring is not moving at all when those 2 raise changes are happening.

[Tucker Jackson]

All good suggestions.

I would divide and conquer.

Unscrew all of the tuning nuts associated with the 4th string so that no levers or the C-pedal are doing anything when you hit them.

Then start adding changes back, one at a time, checking to see at what point the problem returns.

Tune the open E. Then try to tune the F-lever (start here, since you suspect that a little bit of the lowering finger is interfering with the raise). Watch the underside as you work the F-lever. If you do get a little bit of lowering finger movement, try a drop of lube on the rivet in the middle of the changer that connects the raise and lower fingers. If that fails to fix the problem, tighten the lower-return spring a couple of turns.

Assuming all is well there, then introduce the E-lower lever and tune that up. Then the C-pedal, again, watching the bottom of the changer for unwanted movement of the lowering finger.

Good luck!

[Arthur Baker]

Thanks all who have responded!

I have tried all the above methods with no success.

All good suggestions.

I would divide and conquer.

Unscrew all of the tuning nuts associated with the 4th string so that no levers or the C-pedal are doing anything when you hit them.

Then start adding changes back, one at a time, checking to see at what point the problem returns.

Tune the open E. Then try to tune the F-lever (start here, since you suspect that a little bit of the lowering finger is interfering with the raise). Watch the underside as you work the F-lever. If you do get a little bit of lowering finger movement, try a drop of lube on the rivet in the middle of the changer that connects the raise and lower fingers. If that fails to fix the problem, tighten the lower-return spring a couple of turns.

Assuming all is well there, then introduce the E-lower lever and tune that up. Then the C-pedal, again, watching the bottom of the changer for unwanted movement of the lowering finger.

Good luck!

When following these instructions, I notice that after loosening all the nylons, and tuning up the F lever, the lower finger on the change moves slightly, I re-lubricated the rivet in the middle of the change as Tucker Jackson suggested and its still moving. The lower return spring is currently tightened as far as it can go. I also noticed that loosening it does not seem to make any difference. I would assume it would cause the lower finger to move more.

I'll also add that engaging the C pedal moves the 4th and 5th string lower fingers quite a bit, but no adjustment of the return springs have any affect.

[Jerry Overstreet]

It sounds like you've done a pretty thorough investigation, but it still sounds to me that you might have an overtuning problem.

I have had some issues on return springs with a couple of Mullen guitars. First of all, I don't like their system for return springs. They always seem stiff and tight to adjust and those tiny screws don't help the situation.
In certain situations, I have had to replace a few of them.

Another issue is they drag on the plate to which they are attached. If you haven't already tried a drop of oil at each location, try that.

The lower scissors should not move when tuning the raises. This is what makes me think you still have an overtuning issue if you're satisfied the return springs are doing their job.

One way to test that is to activate and release the E string lower lever then before you do anything else, reach under there and see if you can pull the finger/spring back against the plate. If you can, then that means the lower return springs is not tight enough.

Only thing else I can say is just keep revisting the same things that you have been doing.

[Dennis Detweiler]

It sounds like the lowering return spring needs to be removed and a few windings clipped off to gain a little more pull on the 4th string. Maybe the same for the 5th string? When the guitar is upside down and you activate the 4th string raise, the lowering finger is pulling away from the stop? While the raise is engaged, can you push the lowering finger back against the stop plate with your finger? If so, you need more tension from the spring. I also found more changer problems on the Mullen guitars.

[Richard Sinkler]

It sounds like the lowering return spring needs to be removed and a few windings clipped off to gain a little more pull on the 4th string. Maybe the same for the 5th string? When the guitar is upside down and you activate the 4th string raise, the lowering finger is pulling away from the stop? While the raise is engaged, can you push the lowering finger back against the stop plate with your finger? If so, you need more tension from the spring. I also found more changer problems on the Mullen guitars.

Only clip off one coil at a time. I clipped 2 coils off my half stop "finger" spring on my Carter, and it made it very, very hard to activate.

[Bobby D. Jones]

Is the 8th string tuning Open, Raising and Lowering properly?

The 8th string shares cross shafts and levers, With the 4th string, On Raise to F and Lower to D# pulls.