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Hello everyone,


New to these forums but not new to the Variax. Have been enjoying the heck out of this JTV69 for the past couple years. Was a gift from my father and quickly became my favorite guitar not just for the tuning and modeling but also because it's butter smooth, great action and sustain and is just easy to play. My question may be considered sacrilegious, impractical, or you may ask why I would want to do this. Well, because killswitch stuff is fun and I love learning to cover Buckethead. :P


I am trying to install this Iron Age killswitch in the Variax; I understand that a switch would not work on the VDI output, which is fine as I always play conventionally out of the 1/4 inch output, and would mostly use the killswitch with the modeling off like a regular guitar. This thing however has quite an impressive looking 1/4 in jack containing a pc board with two connectors, one with 5 wires and the other with a single wire which I am assuming is a ground. I feel like I'm attempting to disarm a bomb compared to conventional guitars.


Where would you guys install this switch in line with? Or which wires in this connector are what? I am telling myself that despite the complexities of this guitar, all that signal has to funnel down to somewhere on this jack where I can kill all signal with the momentary switch. I am comfortable with soldering and have no worries about the actual installation, but need help with figuring out exactly where in the chain to put this.


Any and all help is greatly appreciated. Cheers!







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There is an aspect of bomb going on here as the socket also acts as:

1) Power switch so if nothing plugged in 1/4 and no VDI power supplied then active electronics are switched off

2) Power Supply - the Ground + Ring connections provide phantom power to the electronics with a suitable floor box

If the electronics are not powered then the magnetics are passively linked to go direct to the 1/4 output, but if they are powered then the signal is switched to a controlled models or magnetics (possibly just relay connects tip to magnetics unless models are active)

Your Killswitch has to interrupt the signal to Tip, but with the PCB mounted socket this probably means breaking a track on the circuit board.


If you want it to only work on the mags then I would look at the 5 way selector or even just a single pickup.


Before you attempt the surgery have you considered that each Model has its own volume setting, so you could have the Position 1 patch set to Les Paul Bridge and Position 2 set to anything but with zero volume. Swapping pickup positions will drop the output signal whenever position 2 is active. This also works with a LP if you turn one of the volume knobs down to zero.

Or if you have an effects unit with a momentary control such as Helix then you can cut all signal when a footswitch is pressed down; even a simple momentary footswitch could be hacked to work this way, if your foot can provide the desired level of control.


Another idea is a custom socket: TRS Socket that connects R & S directly to a Jack while the T is grounded to S by your switch mounted externally on the body.

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Thanks for your reply Rewolf48, and for the explanation of the PCB jack's functionality. 


I have considered doing it via patch or footswitch, but I mostly play with the modeling off and only have a conventional pedal setup (no helix or pod) would prefer to have this actual switch on the guitar.


This is an example of the current jack:


It seems that the best way to accomplish this is with a normally open switch which is routed between T and S, grounding it when pressed (closed).


The Iron Age Killswitch I have is a normally open switch, so If I wire it across the jack's T + S, it will ground when pressed and in effect cause zero volume. Is this understanding correct? If so, I then just have to figure out where on this pcb jack the t and s are.




Would you happen to know the workings of this jack? If I can find what wires of that connector leading to the 1/4in go to the T and S, it may be doable to splice from there?


Thanks a bunch.


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My concern with shorting T and S it that it works fine for passive pickups, but what will it do to the JTV electronics if the model is active and you effectively short the output of the active model circuitry?

I really don't know the answer here; I would think that it should be ok, but what if it causes an excessive load on the output amplifier or causes higher current drain and something to overheat?

Line6 Variax tech psarkissian has warned that just having VDI and 1/4 cables both attached and receiving a signal can cause damage to the circuits as something in there is not intended for the load that results, and I don't need to ask what his thoughts are about doing what you suggest! 

If you turn the part over it should be obvious which solder points attach to the S and T of the Socket, but the fact that you are asking the question raises doubts about your knowledge and I am not confident that you should do this. I certainly have no inside knowledge of the circuitry other from inference based on the functionality. I would really look at shorting the signal at the pickup/switch end and not the socket.

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Power is always colored red for + and black for - (except in rare cases like the mag pickups) so looking at your picture, the tip and sleeve would be the yellow and white wires (four wire connector).  If you have an ohm meter you can find out which is the sleeve easily (not that it makes any difference in this case, but just to check).  However, I echo the concern about shorting the modeling amp since we don't know the effect on it. 

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