NVM1 Wiring

[Droptune]

Hi Everyone,

I am trying to solve a wiring issue with my Nitefly NVM1 wiring. Firstly I have done my best to quickly draw up the current wiring for references: . (direct link to image in case: https://ibb.co/B4BnPD6) It's far from perfect but at least it's a point of reference.

Firstly when using the pickups in the standard magnetic feature the bridge single coil doesn't really come through, although I can't see a major wiring fault. Secondly the Piezo will not work unless I have the output jack halfway in so the tip is on the middle ring which RED wire going to the power switch. In this setting however the bridge pickup does work. If anyone can see a clear error in the wiring diagram please let me know!

Also worth noting changing pickups while in Piezo mode does nothing.

Thanks.

[Fly Rod]

Here's your Wiring Diagram
Welcome to the Forum Droptune
Gary/FLY ROD

[mmmguitar]

the Piezo will not work unless I have the output jack halfway in so the tip is on the middle ring which RED wire going to the power switch. In this setting however the bridge pickup does work.

Is this the same guitar we were discussing here? viewtopic.php?f=10&t=412&p=3167#p3167.

I’d like to make certain of a few things that will help us troubleshoot this:

- Being as your circuit is passive, when you say “power switch”, are you referring to the mag/piezo switch?
- Your diagram there seems to be wired for mono, with two ground wires from the mag tone pot soldered to the TRS jack (this shouldn’t work). Are you using a stereo/TRS cable? If so, do you have a second one for troubleshooting?
- When a mono 1/4” plug is inserted into the guitar, does everything in the mag circuit functions as it should, with the exception of the bridge single coil signal? Is it a constant issue where it’s barely audible, and/or is it a momentary issue where it cuts in and out, or can only be “fixed” by pulling the plug out partially?

There are a few issues with the diagram, which I’ll address once we’ve discussed the above points. The main issue I see in that diagram is that it shouldn’t work as well as you’re describing. If, by chance, you’ve excluded or switched a few wires in the diagram from how the circuit is currently wired, it still seems to be a mono setup blending an unbuffered mag and piezo signal with an on/off/on switch; which would would sound pretty bad. Are you processing the piezo signal with anything, and are you willing to take photos of how everything is currently attached to the pickguard?

[Droptune]

1. Is this the same guitar we were discussing here? viewtopic.php?f=10&t=412&p=3167#p3167. - Yes it is, I apologize if I should of just tacked it onto that thread, same guitar although different issue.

2. Being as your circuit is passive, when you say “power switch”, are you referring to the mag/piezo switch? - Yes Mag/Piezo switch, I'm still learning the proper terminology for some of these different items!

3. Your diagram there seems to be wired for mono, with two ground wires from the mag tone pot soldered to the TRS jack (this shouldn’t work). Are you using a stereo/TRS cable? If so, do you have a second one for troubleshooting? I'm actually using a TS cable I guess, just tip and sleeve I don't have a TRS cable unfortunately although I can get one easy enough. Otherwise yes I've tried other cables etc as troubleshooting.

4. When a mono 1/4” plug is inserted into the guitar, does everything in the mag circuit functions as it should, with the exception of the bridge single coil signal? Is it a constant issue where it’s barely audible, and/or is it a momentary issue where it cuts in and out, or can only be “fixed” by pulling the plug out partially? Yes everything functions as it should from I can tell, other than the bridge pickup not working in Mag mode as noted I should also note the bridge pickup does somewhat come through but it's at maybe 10% volume. It is constant and not intermittent

5. There are a few issues with the diagram, which I’ll address once we’ve discussed the above points. The main issue I see in that diagram is that it shouldn’t work as well as you’re describing. If, by chance, you’ve excluded or switched a few wires in the diagram from how the circuit is currently wired, it still seems to be a mono setup blending an unbuffered mag and piezo signal with an on/off/on switch; which would would sound pretty bad. Are you processing the piezo signal with anything, and are you willing to take photos of how everything is currently attached to the pickguard?

I will do my best to take a photo showing the wiring tomorrow. The diagram should be correct but I suppose a second set of eyes comparing would certainly help!

[Fly Rod]

I'm trying to help
First thing I see that may be a problem is when the guitar cord is plugged into the output jack it completes a circuit..
On the Fly I'm working on it completes the ground loop for the piezos board = Turns the 9 volt battery power ON to the Fishman Preamp
Different.. Hope that Helps..
The RED Switch I would bypass with a jumper taking the DIODE out of the circuit, Does this make the three magnetic pickups function?

I'm in a mess on my project on the electronics too & will remove & test each part away from the guitars circuit one at a time.
I can replace everything except the preamp & it's parts FOR NOW..

Good Luck Droptune
Gary

[mmmguitar]

Thanks, @Droptune - I’ll know more for certain once I see photos. In the meantime, I think some diagnoses can be inferred:

1. @Fly Rod, the guitar’s a passive version briefly produced in the 90s - No diodes to bypass. Essentially, it’s a standard strat circuit, in parallel with a summed piezo signal that passes through a volume pot. Each is routed via an on/off/on switch to separate lugs of a TRS jack.

As such, the guitar requires a stereo cable in order to have the piezo and magnetic signals outputted at the same time, but to two different sources - Their signal paths cannot be mixed in the guitar due to the fact that the piezo signal must be amplified separately, and the signals buffered, before they can be combined/integrated. This is what the battery-powered Fishman boards in the active Flys/NiteFlys do. In these passive NiteFlys, they require the guitar be connected via stereo cable to some kind of powered outboard mixer (many such products are still produced for acoustic players utilizing a piezo-mag/mic setup).

In short: An NFV1 wired up “properly” needs a TRS cable running to two amps and/or a mixer in order for the switching in the passive NiteFly to “work.” Otherwise, a regular TS/mono guitar cable is only going to output whichever of the two signals you have soldered to that lug of the output jack. Generally, you want that signal to be the magnetic pickup circuit.

2. All things assumed to be equal, I suspect there’s both a wiring problem and a misrepresentation of where that problem lies within the diagram (the symptoms being described are not what I’d expect from that diagram).

The signal path needs to be as follows:

-Each pickup’s two wires soldered to their appropriate place on the selector switch contacts and grounded to the underside of a pot. A multimeter will tell you if the bridge pickup has a short in it, though a cold or loose solder joint for the bridge pickup’s lead wire connection to the switch is a common point of failure producing the “faint” pickup signal problem.

-The output from the selector switch goes to the input lug of the volume pot, which shares a connection to the input of the tone pot.

-The middle lug-output from the volume pot is soldered to one side of the on/off/on piezo/mag switch, and then goes to the jack from that same solder point. The function of the on/off/on switch is to interrupt the mag or piezo signal on their way to the jack by putting them to ground. In the middle switch position, neither side is connected to ground. This switch does not combine signals, nor are the signals combined in the guitar - It’s divided lanes. The piezo signal path is described above.

The diagram has stuff like the mag/piezo switch only sending the piezo signal to the jack, with a ground wire from the tone pot being sent to the jack as a signal - If the guitar was wired that way, you wouldn’t be getting signal from any of the pickups.

The diagram seems to assume that pickguard shielding is handling all the grounding connections (e.g. sending the volume and tone pot signals to ground). Is there a fully shielded pickguard grounding the selector switches and pots, a single wire running from one of the pot undersides to the ground lug of the jack, and another running from one of the undersides to the trem spring claw (or bridge post, or some other hardware grounding point)?

[Droptune]

I took some quick photos this morning as a starting ground. I am reworking my office space so hopefully the lighting is sufficient!











Thanks

[mmmguitar]

@Droptune, is there a ground wire running from the middle lugs of the piezo/mag switch to the underside of the tone pot? It looks like there is; which is what we want.

-Someone else may want to weigh in on this: The piezo summing wire from the underside of the bridge seems to be grounded to the underside of the pot, then soldered to the input of the pot. Unless I’m missing something, you either wouldn’t be getting any piezo signal that way, or are passing all of the ground signal from the guitar to one of the signal lugs of the output jack. As things appear, if you unsolder the piezo signal wire from the underside of the pot and just solder the end of it to the input lug it’s currently attached to, then plug a TRS cable in to the guitar, then it may function as intended.

I think we’re more zeroed in on the issues than originally thought, and I’ll probably draw my own diagram, for future reference.

[Droptune]

@Droptune, is there a ground wire running from the middle lugs of the piezo/mag switch to the underside of the tone pot? It looks like there is; which is what we want.

Yes there is, the middle two tabs on the switch are soldered together and then one of the tabs has a bare wire grounded to the tone pot.

Someone else may want to weigh in on this: The piezo summing wire from the underside of the bridge seems to be grounded to the underside of the pot, then soldered to the input of the pot. Unless I’m missing something, you either wouldn’t be getting any piezo signal that way, or are passing all of the ground signal from the guitar to one of the signal lugs of the output jack. As things appear, if you unsolder the piezo signal wire from the underside of the pot and just solder the end of it to the input lug it’s currently attached to, then plug a TRS cable in to the guitar, then it may function as intended.

I'm glad you brought that up, that's been the area I've been skeptical about as it almost looks like it was re-soldered by someone. I will likely grab a TCS cable later today or tomorrow and the unground it from the underside of the pot. Since there is a capacitor there now, would I need to remove the capacitor from the outer tab it's soldered too and then re-solder that to the underside of the pot? Essentially rotate it 90 degrees while maintaining its connection to the middle tab?

I also checked the wiring for the bridge pickup and nothing looks particularly frayed or like it has a poor connection, so I'm a bit lost on that one.

[mmmguitar]

@Droptune, the capacitor bridging the input and output lugs of the piezo volume pot functions as a high-pass filter/treble bleed - You can leave it as is until you get the piezo signal working, then decide from there if you like it or not.

Let’s start troubleshooting the bad pickup: On the input lugs for the pickup selector switch, swap the bridge pickup’s wire with another pickup’s. If the bridge pickup still puts out a weak signal in its new switch position, then there may be a winding break/short in the pickup itself causing the problem. If the different pickup you soldered to the bridge position lug on the selector switch exhibits the same problem, then the fault is likely a short within the selector switch. In either case, replacement is the only guaranteed fix.

I’m glad the wire carrying the summed piezo signal mystified you, as well - There’s no electrical reason at all for it to be grounded to the bottom of a pot (the piezo elements are grounded via the string being in contact with the saddles), and having this ground point in parallel with the input of the volume pot would, as I said, be passing the guitar’s groundings to the jack as the outputted signal. I’d like to understand the reasoning behind that; and can only guess that the signal wire being braided led someone to think it was a ground wire (but wouldn’t explain the other soldering point).

[Droptune]

@Droptune, the capacitor bridging the input and output lugs of the piezo volume pot functions as a high-pass filter/treble bleed - You can leave it as is until you get the piezo signal working, then decide from there if you like it or not.

Let’s start troubleshooting the bad pickup: On the input lugs for the pickup selector switch, swap the bridge pickup’s wire with another pickup’s. If the bridge pickup still puts out a weak signal in its new switch position, then there may be a winding break/short in the pickup itself causing the problem. If the different pickup you soldered to the bridge position lug on the selector switch exhibits the same problem, then the fault is likely a short within the selector switch. In either case, replacement is the only guaranteed fix.

I’m glad the wire carrying the summed piezo signal mystified you, as well - There’s no electrical reason at all for it to be grounded to the bottom of a pot (the piezo elements are grounded via the string being in contact with the saddles), and having this ground point in parallel with the input of the volume pot would, as I said, be passing the guitar’s groundings to the jack as the outputted signal. I’d like to understand the reasoning behind that; and can only guess that the signal wire being braided led someone to think it was a ground wire (but wouldn’t explain the other soldering point).

Oaky so this morning I removed the Piezo grounded to the underside of the pot and connected it to the end tab on the corresponding pot. I chose to still leave that end tab grounded to the pot (I'm unsure if that would be needed still though). I also got a TRS cable and no it's all still a no-go. With the TRS cable and the rewiring I just get pure feedback the whole time, which increases when touching the string. With a TS cable I get feedback when on "Piezo mode" and also the mag portion won't work either. I took a quick snap, please note once get this working I'll need to do cleanup on the underside of that pot!

[mmmguitar]

@Droptune

[Droptune]

@mmmguitar

I realized it needed to be cut shortly after I posted so I went ahead and did it so that connection has now been cut and still nothing. Mag or Piezo, both do not work somehow. I updated the diagram accordingly. Another thing I noticed that I find sort of odd is why does the green wire go from the grounded out tab on the volume pot, the ground on the underside of the tone pot?

[mmmguitar]

@Droptune, I understand chasing gremlins in troubleshooting all this must be frustrating. I hope the experience will pay off in saving you money you’d otherwise spend paying someone like me to wire up guitars in the future (and that eventually your friends will pay you to fool with it ).

The reason the ground/“off” lugs for your pots have been soldered with connecting wires that end up at the underside of a single pot is because the circuit design assumes that the pots being in contact with the pickguard shielding will be a solid ground connection. If you don’t have a multimeter to test continuity between these components, you can err on the safe side by bending those pot lugs back to the casing and soldering them the way most volume pots are, then ensuring an extra ground wire or two is soldered to the underside of all three pots.

Just for illustration, here’s how I would have approached the guitar if it was on my workbench:

1. Make sure everything was connected according to a linear signal path that makes sense (and desoldering any connections that don’t; e.g. that piezo wire bridging the volume input and ground).

2. Understanding that the circuit is two passive circuits converging in parallel at an on/off/on switch that sends each signal to a stereo jack, I’d troubleshoot signal loss from both circuits resulting whether I used T/S or T/R/S by isolating each circuit and soldering the output from each volume pot directly to the jack (one connection at a time). If this fixed the issue, then that tells me the mag/piezo switch isn’t doing its job. If not, then I work on the signal path of each circuit at a time, moving backwards in the signal path one component at a time. With most guitar circuits, I can troubleshoot them just by looking under the hood while they’re plugged in to an amp. With control cavities that resemble spaghetti factories, I use a multimeter to be sure I’m not misunderstanding the signal path.
3. Eventually complete repair/restoration after pulling all my hair out and telling myself I’ll just pay one of my friends to deal with it next time.

[moreteavicar]

@Droptune, Hey, did you resolve this or not? Your wiring in the photos looks almost the same as my NiteFly NFV1, just a few observations:

The Piezo shield has to be grounded to the pot in the same way the other end of the mags are grounded - its the "cold" end - you have no circuit otherwise. The hot end goes through the DPDT switch as you've identified.

The tone control is for mag not piezo (just a typo as you clearly show it wired to the 5-way, but thought worth pointing out)

There should be a ground (green wire) link between all three pot bodies
There should be wire link from DPST switch middle to the Tone pot body (as well as both pins of the switch connected - this makes it "on-on-on")

Might be worth doing this, if you're handy with a soldering iron and multimeter: de-solder the mag grounds, separate the wires then measure the impedance of each coil, relative to the connection at the 5-way selector, then after the 5 way selector (moving switch accordingly) to see if there's a significant increase in resistance at Bridge compared to other positions.

Hope these pictures help:

[Droptune]

@moreteavicar Thanks for the photos that helps immensely! Funny enough right before you posted this I dropped it off to a tech to try and sort it out because I was having no luck! I definitely wish I had seen these sooner, I would of saved myself some grey hairs and money

Anyways I took these photos and your comments and sent them along to the tech, they should certainly help him troubleshoot. I really appreciate the photos and will update when it’s back, hopefully before Christmas!

Droptune

[moreteavicar]

@Droptune Hey no worries you're welcome - guess I'm doing the reverse of what you're doing (fitting Ghost expander)... who knows maybe someone might want to do the reverse of that in the future

[Droptune]

@moreteavicar Alright so the guitar is finished I just need to go and pick it up! My one question I how do (or did) you go about using the Piezo on the NFV1? Did you use a Y-cable, a preamp, two amps or anything else? I’m trying to decide on how I want to go about it.

Thanks

[moreteavicar]

@moreteavicar Alright so the guitar is finished I just need to go and pick it up! My one question I how do (or did) you go about using the Piezo on the NFV1? Did you use a Y-cable, a preamp, two amps or anything else? I’m trying to decide on how I want to go about it.

Thanks

Dang, sorry for late reply, never got the notifications!
I built my own dual channel JFET mixer years ago, plenty of examples on the web - you can't connect piezo to mag directly dues to vastly different impedances.

How is the axe?