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RobertBuchholtz

When I use the whammy bar the 2nd string sound disappear

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Hi all,

 

Have someone the same problem as mine?

 

When I use the whammy bar with my JTV-69 (using the simulation / variax mode - i.e. piezos) th sound of the second string (B) disappear! As soon I return the whammy to the right position, the sounds come back.

 

I already tried to change the angle of the string (saddles high and bridge high lowering and lifting), changed the string, took every string out installing it back, cleaned the faulty piezo.. nothing.

 

I realized that all the other piezos are kind of clued or sticked to the bridge and this one was loose from the beginning.

 

Best regards,

 

Robert 

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At best it's a bad ground return on the 2nd string.  At worst, a bad piezo element.  The grounding arrangement on JTV-69s is poorly designed as it relies on contact between dissimilar metals.  I'd start by removing the B string, hitting the bridge piece with a shot of non-residue contact cleaner and working it around a bit with your finger.

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At best it's a bad ground return on the 2nd string.  At worst, a bad piezo element.  The grounding arrangement on JTV-69s is poorly designed as it relies on contact between dissimilar metals.  I'd start by removing the B string, hitting the bridge piece with a shot of non-residue contact cleaner and working it around a bit with your finger.

 

Ok Thanks. Will try to clean it and see if it improves. So if I understood correctly, the ground is done via the enclosure / metal contact between the bridge and the piezo itself. So if this is the problem, probably if I force a ground contact using a wire touching the piezo shelf / enclosure during the failure, the sound should come back, right?

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In theory, yes.  If you can make the problem persist for long enough it's worth a try.

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In theory, yes.  If you can make the problem persist for long enough it's worth a try.

 

Thanks again!!

 

I´m really considering the soldering the extra ground wires as you and other suggested. I´m in Brazil and the humidity is very high over here (what I read also is not good for the piezos).

 

One more question: Have you soldered directly or have you used a cold epoxi clue for that (at the piezo side I mean)? Do you perhaps have a photo (from the piezo soldering side) to see how you have done the procedure? I´m a little afraid to damage the piezo with the heat of the solder so I´m checking if I can find the epoxi mentioned in another topic.

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I soldered the wire directly to the inside of one of the little tabs on the bottom after clearing away potting compound with a hand-grinder bit.  The element was clamped in a steel hobby vise to act as a heat sink.  The element case will take solder if you work carefully and use flux.  Heat damage is always a possibility, which is why I don't recommend this for anyone unsure of their soldering skills.  Elantric (VGuitar Forum founder) recommended the conductive epoxy, but I decided to take my chances with soldering. 

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If it occurs while using the Trem bar, then typically, the Tremolo tension and/or

B-string piezo saddle needs adjusting. Especially if you're into "dive bombing".

 

"At best it's a bad ground return on the 2nd string"--- good guess, always on the

ball. But if it was a bad ground, all of them would have the problem. A failed piezo?

Maybe, but then it would have problems even if the Trem bar wasn't being used.

 

At this point, prime suspects would be piezo saddle adjust or Trem bar tension, 

snhirsch's suggestions would be 3 and 4. After that I would recommend a local

Line 6 authorized service center in your area.

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I stand by my statement.  If the B string piezo shell has an oxide build-up that prevents it from making good ground contact with the bridge, only that element would will be affected.  This happened to my JTV-69 (on the low-E) and is the reason I installed the ground wires.  So, it's not only a "good guess", but it's one that has proved correct in the past.

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I'm familiar with Mr Buchholtz's problem though the ticket system, most

of it is problems with his set-up. But yes, quite right snhirsch, I've seen

that happen, rather rare fortunately.

 

The saddles are grounded as is the bridge. That you would need extra,

is rather curious. Burlington, Vermont,... moisture a bit higher down there?

 

Most of what I see is losing signal during a dive bomb on the Trem bar.

That's easily adjusted for. Cases like what snhirsch had, can occur.

 

I've seen a couple, as well as few seriously corroded ones from the Great

Lakes or Gulf Coast areas where moisture can be a problem with metal

parts. Had one in recently from Key West, some of the worst corrosion

I'd seen in several years.

 

Start from the top of the suspect list and work your way down, eliminate

all the possibilities systematically.

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The saddles are grounded as is the bridge. That you would need extra,

is rather curious. Burlington, Vermont,... moisture a bit higher down there?

 

On a JTV-69 the saddles are grounded only by virtue of mechanical contact with the bridge piece and the bridge pieces are grounded only by virtue of the height-adjust screws and the intonation screw.  At each juncture you have dissimilar metals, which is an invitation to electrolysis based corrosion.  It's a bad design choice. 

 

And, by the way, Burlington, VT is "up" there adjacent to the Canadian border.  It goes from Sahara Desert dry in mid-winter to steam bath in the summer - and everything in between.

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"... saddles are grounded only by virtue of mechanical contact with the bridge piece and the bridge pieces are grounded only by virtue of the height-adjust screws and the intonation screw"--- mmm,... not quite, but close. More to it than that. Dis-similar metals,... not entirely.

 

Oceanography research vessels I've been on, they have three of everything when it comes to electronics. A prime, a back-up secondary, and one in the shop for servicing. And they all get cycled through constantly in that sequence, always two on board at any one time. But yeah, metal and high mineral content moisture can wreak havoc on all sorts of metallic surfaces and electronics.

 

"... grounded only by virtue of mechanical contact with the bridge piece ..."--- no, afraid not.

But that's circuit level stuff I can't get into with end users.

 

Yeah, geography,... some up there refer to it as down there. Just given them their props.

Nice to know you're always on the ball here. Thanks.

 

But Mr Buchholtz's ticket was a problem with set-up. A bad set-up can mask a host of other problems.

Once the set-up is done, all the other stuff will fall out and show itself in a more apparent way.

But yeah, moisture will be at play as well.

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"... saddles are grounded only by virtue of mechanical contact with the bridge piece and the bridge pieces are grounded only by virtue of the height-adjust screws and the intonation screw"--- mmm,... not quite, but close. More to it than that. Dis-similar metals,... not entirely.

 

Oceanography research vessels I've been on, they have three of everything when it comes to electronics. A prime, a back-up secondary, and one in the shop for servicing. And they all get cycled through constantly in that sequence, always two on board at any one time. But yeah, metal and high mineral content moisture can wreak havoc on all sorts of metallic surfaces and electronics.

 

"... grounded only by virtue of mechanical contact with the bridge piece ..."--- no, afraid not.

But that's circuit level stuff I can't get into with end users.

 

The "we can tell you, but we'd have to kill you" BS is getting very old.  There is one wire emerging from the pickups.  That de-facto means that mechanical contact along the path to the nearest circuit ground (the little PCB on the trem block) is the ground scheme.  You can claim trade secret, voodoo or anything else you'd like to, but that doesn't alter the laws of physics.  Sorry to be testy, but this answer comes across as more condescending than usual and I'm tired of biting my tongue. 

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There is no "... "we can tell you, but we'd have to kill you" BS", going on here.

 

I'm not claiming "... trade secret, voodoo or anything else ...". I simply can't get into

circuit level stuff with end users. It's that grounding is trickier here with these, since

there are pick-ups as well as piezos. Don't worry, the laws of physics are still intact.

 

I can get into some generalities and recommend a way to proceed. I do this as a

courtesy and they let here,... so long as it does not cut into my time repairing stuff.

 

If you're looking for more inside info, becoming an authorized service center. You're

a sharp guy who knows stuff.

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