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How Do Jtv Piezos Ground?


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#1 clay-man

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Posted 01 August 2013 - 12:21 AM

Question. Does the JTV use the horrible contact-to-bridge grounding technique that the original variaxes did, or does it have it's own grounding wires?


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#2 davidb7170

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Posted 02 August 2013 - 10:31 AM

Yes they do use the case ground for the ground terminal -- the piezo's have a single hot lead output.

 

I have a 59 and a 69S. I got my 59 in May 2011, after ordering in Oct 2010... Long wait. They were fixing the defective switching issue at the time, but mine slipped through with the switch problem. I returned it to L6 & they fixed it in a pretty short time and that issue has been fixed ever since.

 

Then later that summer, about July 2011, I was playing some outdoor festivals in hot humid Iowa summer weather, and my 59 piezo for the low A string would cut out. My bridge was also corroding on the top side where your hand rests. I again contacted L6 and it took a bit longer this time to get resolution. In the meantime, I took along a small handheld hair dryer -- it would dry out the contact, and I could get the piezo going again -- kind of a pain in the a$$... I only had the problem in outside hot humid conditions and never when playing an inside gig.

 

I finally convinced L6 that I could replace the bridge myself rather than take my guitar out of use for the amount of time it would take to ship and have them do it, so they sent me a new bridge with piezo's and I swapped it out in minutes. That was early 2012. I have played 2 seasons of outside gigs since then, and have not had any issues since. The bridge has remained shiny and not corroded. I also have not had any of those issues with my 69S that I purchased in Oct 2012.

 

I heard the Korean factory had some issues with their hardware contractor, and have since replaced that contractor and re-designed the bridges. I do know the bridge I replaced had different casting markings on the underside....

 

Back to your question -- when I was replacing the bridge unit, I saw that the piezo's all have a single lead coming out, and use the case to bridge connection for the ground. Oddly enough, the printed circuit board terminal board under the bridge has 2 solder pads for the piezos -- one hot that the piezo lead is soldered to and one ground that has nothing soldered to it.... I would guess that a 2-lead piezo would also work, if one could be found that fits the box in the bridge.... Don't know that for a fact, just guessing...

 

Dave


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#3 clay-man

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Posted 02 August 2013 - 01:15 PM

Well as long as it's more well built than the original Variax bridges. I know graphtech ghost has ground wires for each saddle and I think it's a lot better than relying on the piezo's physical contact with the bridge. Not the best design idea when you're gonna be touching it quite a bit.


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#4 snhirsch

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Posted 03 August 2013 - 05:10 PM

Yes they do use the case ground for the ground terminal -- the piezo's have a single hot lead output.

 

I could swear that the saddles in my JTV-69 have a braided shield on the lead wires.  Are you saying your 59 has no shields?  Given that piezo transducers are very high-impedance devices I find that surprising.


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#5 davidb7170

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Posted 03 August 2013 - 05:49 PM

I'll try to upload a picture of the replacement bridge I installed --

 

We'll see how it goes. My luck has been spotty at best with picture uploads.....

 

Anyway -- tell me what you see. I don't see any braiding, just grey plastic insulation...

 

Dave

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#6 snhirsch

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Posted 04 August 2013 - 05:25 AM

I'll try to upload a picture of the replacement bridge I installed

 

That's a completely different arrangement from the JTV-69!  It sure does look like they use the bridge casting as ground return.  A poor idea IMHO, for all the reasons you brought up. 


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40 years of Rock-n-Roll and proud of it!

 

PRS Custom 24 (1990) w/ GK-3 Hex PU

James Tyler Variax JTV-69(k) w/ Strat Neck

Roland GR-55 Guitar Synth

QSC K10 FRFR

 





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