Piezo Pickup Not Producing Sound - Troubleshooting Help?

[no doz]

A NiteFly came across my bench this afternoon with a request to fix a Piezo pickup that's not making any sound. I've been teching for a good amount of time but this is the first encounter I've had with a Parker or a guitar equipped with a Piezo. I'm looking for a bit of troubleshooting advice from those who are experienced with these instruments before I start poking around inside.

The magnetic pickups, magnetic volume and tone controls, magnetic pickup selector switch, and the mono / stereo button all function as they should. I get no sound from the Piezo pickup when the Mag / Piezo three-way selector switch is in the middle or back position. The Piezo volume control also does nothing.

My first inclination was to test the battery. It measured right around 9V on my meter and fully powered a pedal when connected. The battery also makes an audible clicking sound if I insert it while the guitar is plugged into an amp. Not sure if this is a clue as to where the issue may (or may not) lie.

Would love any advice as to where I should look first or what specific order I should follow as I attempt to rule things out. I haven't gotten under the hood yet, but I'm not sure how much the guts differ from more standard instruments or if there's a common problem area where these pickups tend to fail.

I'm slightly intimidated by this guitar and it's for a fairly high profile customer, so any help or suggestions would be greatly appreciated! Will be digging around this forum in the meantime. Thanks so much!!

[vjmanzo]

Hi @no doz, and welcome!

It sounds like something is wrong with the Fishman NiteMix pre-amp inside of the guitar. If you look inside, you’ll see that the piezo elements under the saddles connect to a summing board under the bridge and then the signal connects to the preamp. It’s less likely that the connection from the summing board is the problem and also not likely that all of the elements are failing...so that leaves the preamp!

It’s possible that the preamp in there is failing for some reason, so, worst case scenario: you can replace it with a Fishman Powerchip (discontinued, but you can still find them), or you can use the Graphtech Acousticphonic Preamp. I can’t recall if there’s a trim-pot on the preamp in your client’s NiteFly, but, if he or she is not the original owner, it’s possible that the previous owner simply turned the trim down.

People don’t always “get” the value of the piezo, so it’s not entirely uncommon for those folks to start disconnecting things! Depending on your model of NiteFly, disconnecting the piezo from the toggle switch would still allow the magnetic pickups to work as expected even if the piezo preamp had no power!

No worries or apprehension needed—were here to help! Feel free to post some photos and many of us can help look for irregularities.

[no doz]

Amazing, thank you so much for your help vj! I appreciate you taking the time to respond

when i get it open tomorrow i'll take a look for any loose wires / cold joints / obvious disconnects, then i'll check for a trim pot, and then i'll see if i can rule some things out using my multimeter. hopefully it's just something simple, but if i get snagged i'll post up some photos for sure

thanks again!

PS - i'm a NYer also, love that. hope all is well and that you're staying happy / healthy!

[vjmanzo]

Happy to help, my friend! Stay safe as well!!

[no doz]

Ok so I removed the guard and looked inside today, and the guts are much simpler than I thought they'd be. Your post helped me make quick heads and tails of everything going on inside VJ, so thank you again.

There are no broken wires or bad connections anywhere in the circuit, and aside from some unsightly flux, all appears well. I suspect the issue might be component failure on the PCB preamp like you had suggested, but I'm not positive. There is a lot of white powder in the cavity which I think is oxidation, could explain a potential malfunction. Is there a specific test any of you know of that I might use to help deem the PCB the official culprit?

Here are some context clues that I found when poking around with my multimeter:

- I have connectivity from the 9V battery box to the point where it connects to the PCB. I believe that plus the amplified sound it makes when inserting the battery effectively rules out the battery box as a suspect.

- I have connectivity from the Piezo pickup input point on the PCB board out to each terminal on the three way switch. That plus the fact I get sound from the magnetic pickups in two of the three switch positions likely rules out the switch.

- I have connectivity from all six saddle soldering joints on the summing plate out to the point where it connects on the PCB. However, I do not have any connectivity between from the little balls on top of the saddles and the summing plate for three of the six saddles. I'm not sure if this suggests there may be an issue with some of the Piezo elements (could just be my ignorance of Piezo pickups function). I'm also not sure if this would rule out an additional issue later in the signal chain, assuming that if even ONE of the Piezo elements were working properly I'd get some sound from the pickup if everything else was in the circuit was in functional order.

Here are a couple pics for reference also, would highly appreciate any second opinions!

[vjmanzo]

Glad this is working out, @no doz! Thanks for these photos!

I’ll let others chime in, but my spidey sense tells me that the preamp is, in fact, the problem, and then if you switch to, for example a Fishman power shape, you’ll be in good shape!

I’m not an expert with piece of electric transducers, but I do know that when we did our 12-string Parker Fly mod a few years back, you need pressure on those elements in order to get them to work right and it was a little difficult to test what they were actually doing without having strings on the set. All that to say: they’re probably fine, and the lack of any signal, to me, makes me think that the preamp is dead.

Again: I’m not an expert, so I’ll defer to others on this! If it were me, I’d just scoop up a Fishman Powerchip and try it out.

[no doz]

i did some more research on how exactly the piezo functions and i think you're right, the bridge saddles are likely fine. i'll snag a powerchip and give it a go!

hopefully it's a direct-ish replacement situation where the soldering points are obvious, but if it requires some sleuthing it's comforting to know that this board exists as a resource. have learned a lot clicking around on here already

drop your venmo handle if you've got one bud, i'll buy you a coffee as a thank you!! haha

[vjmanzo]

Hi @no doz— happy to help!

And, in optimism: I’ll take my cup of coffee in person once this pandemic is over and I’m next in your area, so let’s keep in touch!

[no doz]

Sounds good VJ, I appreciate that optimism. I live in Park Slope if you're ever around

I picked up a Powerchip and new output jack today and I'm preparing to install. I have just one final thing I'm uncertain of, maybe someone here can help!

There are three wires coming off of my magnetic / piezo three way selector switch, but the Powerchip only has one available pad marked for the three-way switch, as seen here:



Do I solder just one of these wires to the Powerchip pad? Solder all three of them together and then run a little jumper to the pad? There's a pic a few posts up for reference, black wire is Mag only, green wire is Mag / Piezo, Red is Piezo only. Everything else but this seems crystal clear

[vjmanzo]

Hi @no doz—great!

I'm a bit out of my league to say with any certainty as to how to proceed, so I’ll gladly defer to someone else’s expertise. However, I am certain that the Powerchip on a refined Fly, the three-way switch is an on-off-on switch like this, and, (less certain), does something interesting with the ground signal from that three-way switch. Sorry to be so vague; I'm not certain how it works.

Have you seen the Refined Fly Wiring Diagram) and the Fishman Powerchip User Guide?

[vjmanzo]

Hi @no doz--just a heads up that we've posted more schematic details about the NiteFly here.

[no doz]

Thanks @vjmanzo !!

It turns out the online version of the powerchip manual has a wiring diagram for the three-way switch that my physical copy does not, otherwise they're completely identical. So strange

I got the powerchip and new output jack installed successfully, but still had no sound from the piezo. It turns out there was an additional issue - a short underneath the low E string saddle that was causing the entire summing bar to ground out. Once that saddle was removed from the bridge the piezo started making sound again and outputting properly. Never been so relieved to hear a pickup hum haha

I found a replacement saddle online and ordered it, with a touch of luck my next post will be an official declaration of victory

[vjmanzo]

Fantastic @no doz! Great to hear!!

[no doz]

The replacement saddle worked perfect. Closing out the book on this one, the guitar is officially repaired! Thank you for all of your guidance VJ. I now understand both the appeal and some of the idiosyncrasies of these really unique guitars. I learned a lot and I appreciate all your help very much

Be well + stay safe my friend!

[vjmanzo]

That’s such great news, @no doz! Glad you persevered!!!

Stay safe and well!