Pitch Jumps On Raise/Lower Levers

Les Ford · From: British Columbia, Canada

I'm just putting together an all pull guitar with a bog standard scissor finger setup and I am having pitch problems on the raise/lower knee levers.

I have tuned the guitar up to resting pitch and then have tuned the raise levers for left and right knees so that I can raise for both knees and they both return to pitch with no problem.

I then go to tune the half step lower levers but as soon as I engage the lower there is a distinct pop or click in the linkage and the resting pitch of the string drops. At this point the guitar is out of tune until I engage the raise lever again, which resets to the original resting pitch. This problem is repeatable for both knees.

It seems like something is binding and popping loose in the changer but whatever it is is not readily visible from the outside of the guitar. Is there a likely suspect for this problem that springs to mind?

Could this be caused by the finger rivets being too loose? Another possibility I am thinking of is that the two halves of the fingers are binding because of misalignment with the return springs but everything is working fine for the raise side.

John Hyland · From: South Australia

Are the lowers returning correctly and resting at its usual stop?

Ian Worley · From: Sacramento, CA

More specific info, including some pics will yield more useful replies here. It sounds like you can't see or locate where the click/pop is occurring when you flip the guitar over and engage the lever. Can you tell whether it's occurring in the changer or somewhere else in the linkage? I've seen poorly setup guitars with a 90 deg bend at the bell crank that if sloppy, would slip and "pop" when a change was engaged. I think there may be a typo in your first sentence, "bog", not sure what that means. Are the fingers homemade, or from a specific make model of guitar? Do the fingers ride in a "comb" or are they just free floating against a stop bar? Are the lowers returning flat or sharp? Is it consistent? Are the pull rods pulling straight, perpendicular to the changer axle? Are the lower return springs adjustable? If too tight they could cause the string to return sharp; if too loose the lower may not return fully. The clicking/popping could be associated with this too. It sounds like the sort of problem that could be related to the lower return spring tension, but it could also be a dozen other things. A couple of pics could provide a lot of useful info.
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All lies and jest, still a man hears what he wants to hear and disregards the rest - Paul Simon

John Hyland · From: South Australia

Bog standard means unchanged from manufacturer , probably a commonwealth saying.

Try touching different parts when activating to feel (or stop) the click which maybe will give a clue where it is happening.

Les Ford · From: British Columbia, Canada

I think I may have run it down. It looks like I mis-measured the comb and the spring rack so that the fingers are hanging off the axle at a twisted angle. I'm going to recut these parts and see if that solves it.

Jim Kennedy · From: Brentwood California, USA

I had a similar problem with my Sho Bud. A couple of the fingers had worn rivets, doing what you described initially, so I ordered new fingers from John Coop. After putting it back together, nothing seemed to work right. A quick consultation with John and a couple pictures later, problem solved. According to Mr. Coop, Sho Bud was not real critical about tolerance. Just grab finished parts, if they did not quite fit, find a part that does. John made all his parts to very tight specs. When I put my guitar together, the comb and fingers did not align properly. The solution was to mill a few thousandths off of the bottom of the housing that holds the fingers. A little knowledge, a little perseverance, and all is well in the PSG universe. Glad you solved it.
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ShoBud Pro 1, 75 Tele, 85 Yamaha SA 2000, Fender Cybertwin,

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