Troubleshooting the Piezo on a '99 MidiFly

[roninracer]

Hi,
I searched through the forum (for a couple hours) and wasn't really able to find the information I was looking for.

This is mainly precipitated by a Powerchip replacement I recently performed on my '99 MidiFly.

Basically I need a way to test my Piezo pickup to make sure I'm getting a signal from it (since nothing comes out when it's switched to piezo only).

The mags work so the Powerchip is functioning.

My concern is the MidiAxe nonsense that's connected to the bridge and whatnot. I can't find decent schematics on how all of that is connected.

Ideally I'd like to pull that monstrosity out of the circuit completely since it's only a battery vampire at this point with no useful purpose.

I'm not really interested in having Midi in the guitar (it's cool but a useless toy for me) so I was thinking maybe I can convert a midi cable (and one of the midi jacks) to supply power to the Fishman Powerchip since 9 volt batteries in guitars annoy me to no end.

Anyway if anyone has any wiring breakdowns of the MidiAxe stuff and a good guide on how to troubleshoot the Piezo in a MidiFly, I'd really appreciate it.

Thanks!

[vjmanzo]

Hi @roninracer and welcome! I moved your post to this NiteFly forum where more NF users will likely see it.

Were the piezo undersaddle elements working previously?

You likely know this if you've installed the Powerchip, but there is an option to route the mags on the ring of a TRS connection with piezo on the tip signal; it's possible that this is engaged depending on how it's wired up. Do you have a TRS insert cable? If so, plug it in and you may hear the discrete signals on the two ends of the TRS cable.

Have you seen the MIDIFly manual in the Manuals section?

[roninracer]

Hi @vmanzo !
Thanks for your reply.

I don't have the TRS cable to try that but I know about that and the mechanism involved. I think I've got a stereo to L/R split converter somewhere, that should work for that purpose as well correct?

In any case I should get a signal from a mono cable too.
I have seen the manual but it's really useless for what I'm trying to do/need to know.

Do you think I should pull the jack to make sure the Piezo hot lead is still connected properly to it? I was planning to do something like that anyway since I wanted to know if I could see a signal from it with my meter (I do have a scope if that's what I really need).
The jack is wired as you suggested. It's also got the battery kill setup too.

I started to look under the bridge to see where it starts from and it's a big mess under there with a lot of connections to the MidiAxe board.

So I wanted to see how that was all set up before I started dismantling it. From what I can see, it looks like there's individual wires coming from each saddle (all dark grey) and then there's a mini pcb with a wire cluster (not the TFT kind) and rectangular multipin connector that looks like it connects to the MidiAxe board on the other side. Could that little PCB be a 'normalizer' (I think that's what it's called) ?

I just can't get decent schematics on this setup to know what to pull to test.

Also the wire that's supposed to connect to Piezo hot on the PowerChip is strange; It looks like it was painted with white paint is very thin and fragile and light grey underneath. Of course this isn't the actual hot since that goes to the jack so I'm thinking it's the shield? There's a pad on the PowerChip for that as well next to the common ground pad so I'm not sure at all.
I took some pictures of the old PowerChip connections to make sure I didn't screw the replacement up. For most of the connections it makes sense but I am having a hard time with the Piezo setup to know how to troubleshoot it. I did check the other NiteFly schematics to see if there was anything different but it doesn't seem like I screwed it up. I really appreciated the one that listed the wire colors. That helped me immensely when the blue wire from the mags came off the PowerChip selector switch and I had no idea what it was connected to.

Oh and I also tested that switch to make sure it had continuity (as other threads mentioned they fail).

[vjmanzo]

Happy to help,

I don't know if a splitter will give you a proper analysis; you'd need something like this or the cheap-o fast-shipping alternative


The smartjack on your MIDIFly--if it has a smartjack--should sense if there's a TRS cable connected and automatically do the proper routing of piezo signal to tip and magnetic pickups to ring, but if a mono cable is connected and there's something wrong with either the jack or the wiring to/from the Fishman, then this detection can go awry and your guitar will think its being asked to output stereo even if a mono cable is connected.

Can you post some photos? If your intention is to simply remove all of the MIDIAxe tech anyway, then we just want to make sure that the parts you're keeping all work individually, so that when you re-connect them, you don't have any surprises; do I have that correct? If so, we need to check:

• magnetic pickups

• piezo saddles

• piezo preamp (Fishman powerchip)

• switches

• pots

• stereo output jack

Seems like you've been able to identify that most of these things work already, so my money's on "the jack is not wired correctly/jack thinks it should output piezos on tip and mags on ring" or "three-way toggle switch (mags alone/mags+piezo/piezo alone) isn't working".

[roninracer]

Ok I will take a shot at posting images (wish me luck)

This is the jack panel pulled:


Same but at a different angle:


Top view:


MidiAxe board:


Under the bridge showing the Piezo wired going into the mini PCB with the rightmost two wires on the connector being the Piezo hot and maybe shield?


This shows the other side where the weird painted grey wire and other grey wire split off; one going to the PowerChip and the other going to the 1/4" jack. Also shown is the other side of that set of rainbow wires (which those 2 grey wires are a part of that cluster).


Closer look at that rainbow cluster with the 2 grey wires coming out:


Even closer shot


PowerChip connections

[vjmanzo]

Thanks, @roninracer; the pictures came through just fine! Very helpful!

Okay--seeing the innerworkings of the MIDIFly, I need to withdraw some of my earlier comments as there are some notable differences between it and a typical NiteFly; the jack for example. Sorry about that! The photo showing "Under the bridge showing the Piezo wired going into the mini PCB" is certainly different than a typical NiteFly that has a piezo summing board there.

I'll defer to others with more familiarity with the MIDIFly wiring--wish we had an actual schematic to refer to here! But for sure, my approach would be to check the switches, pots (e.g. small stuff) first.

#MIDIFlyResources

[roninracer]

So here's my guess, is that the Piezo summing board, also allows each string to go out individually to the MidiAxe board so the two grey wires that come out are the shield and the summed Piezo hot. The others go directly to the MidiAxe as individual signals for processing.

On my examination of the jack, I had to strip and reattach 3 of the wires on it. It's not normally a stress area, but I think those 20 year old wires have seen better days and were pretty brittle.

After that I was able to get Piezo signal out of it which is really good. My guess is the Piezo shield was the culprit.

One thing's for sure that MidiAxe sure make a mess in there. At least it's not the TFT ribbon wires I really don't know what Parker was thinking with that setup

[roninracer]

So an update,
I put it back together and strung up the guitar for testing.

The Piezo works as expected.

But the Mags are really low and distant sounding with an incredible amount of hiss and noise.

I'm not sure if it's the battery (I'll replace that and try again) but there's something funky going on with them

My thoughts here are:
1. The PowerChip blend attenuator
2. A ground loop somewhere
3. low battery
4. My botched wiring.

[vjmanzo]

Wow! Great development, @roninracer! Keep us posted!