Pre Refined fly no piezo sound - deeper dive question

[Floydwhammy]

Hi everyone!
my 98 fly deluxe piezos stopped working but like others have posted here the mag p/u's still work. Thanks to everyone's previous piezo problem posts I've cleaned the ribbon cables and metered all switches for continuity to make sure all those switches /pots work. But then I finally metered just the shielded wire coming from the bridge piezo's into the body cavity from the 2 points where the shield and center conductor are soldered to the top of the fishman circuit board and I get no continuity. So I'm thinking it must be upstream at the bridge area? so before I go too deep taking the bridge apart I'm looking for any advice on what to look for taking the bridge apart or how and where to look at the bridge piezo system itself. I've gathered from others posts that each saddle has its own piezo and assume their wires all attach to a summing circuit board under the bridge maybe and that is why there is only one shielded wire coming into the body cavity from the bridge and not 6 individual wires for each piezo. Could there be a common solder joint there that let go causing all the piezos not to work, and tips on what to look out for when taking the bridge out if I need to so I don't damage the bridge mounting posts from the experience of those that have gone here before me.
Again thanks to all who keep this board going with great suggestions to the parker community.

[Floydwhammy]

FWIW...If it helps anyone else here, I still haven't figured out why my piezo system isn't working yet but I finally figured out an easy way to test the piezo system to make sure piezos are good as I thought my problem might be the failed piezos themselves or the wiring connections in the bridge. This is to test the piezo/ bridge wiring itself only, directly, before it hits the preamp circuit board. The 6 piezos themselves are soldered together to a single common strip in the bridge. then a single coaxial cable (center conductor with outer shielding) goes from that common strip through the body into the electronics area and soldered to the preamp board. you can see in the attached pic on either side of the tip of the pen the 2 blobs of solder on the preamp circuit board. to the left side of the pen tip is the solder blob holding the outer shielding of the single coax cable from the bridge and to the right of the pen tip is the solder blob holding the center conductor of the coax cable. I had a guitar cable that had one end missing with the wires showing so I plugged the good end with intact 1/4 " connector into an amp and used alligator clipped wires from the stripped guitar cable end to the preamp circuit board. I clipped one alligator clipped wire onto the actual shielding of the guitar cable and to the shielding of the coax cable on the preamp circuit board (left side of the pen tip) then I clipped another alligator clipped wire to the center conductor of the guitar cable and as i turned the amp on and strummed the guitar I touched the alligator clip from the guitar center conductor the blob of solder to the right of the pen tip where the bridge center conductor is soldered. All this to say all My piezos still work perfectly and are not the problem! So a small win knowing for sure the piezos and bridge wiring are not my problem. Now back to the drawing board when I have time . At least I can use the guitar with the humbuckers. Wonder if Fishman still has any of these older style preamp circuit boards left that we could just swap out. That would be too easy!

[vjmanzo]

Hey @Floydwhammy—good news that it’s not the undersaddle piezo elements themselves! That’s a way less-invasive fix as you don’t need to touch your saddles!

Sadly, Fishman only made that board for the Fly during the first decade. If the board is the failure point, you’d have to replace it with something comparable like the Fishman Powerchip, but that would also require you to ditch the flex PCB. We’re actively developing replacement Flex PCBs, but haven’t even started to consider replacement Fishman boards. But it sounds like the Fishman board is working, right?!

Can you test to see if the red button near the battery compartment is functioning?

Can I ask—have you tried turning the trim pot on the board?

#PiezoIssues

[Floydwhammy]

I think the FIshman board is working but only because some others have posted about their humbuckers still working. I can still get the mag humbuckers to work if the red stereo mono button is pushed outward. But that still doesn't tell me for 100 percent if it is the board or not because I think you pointed out previously somewhere that both the piezos and the humbuckers run through the preamp board for whatever reason they chose to do it this way. But just because the humbuckers work I'm not sure if that confirms that the board is good?

Yes I've tried turning the trim pot on the board but still no piezos. The next thing I think I may try is to take the circuit board out and resolder each individual solder joint to see if any of the solder joints have failed. Or possibly bypass the piezo volume/tone pot. I have put a meter on all the switches, pots and each individual line of both flex pcb cables and they all pass continuity tests. So I just haven't figured it out yet. But now that I know the piezos and bridge are fine I'm leaning more towards the preamp board or possibly the red stereo mono switch although that passes continuity on the outside contacts where the flex pcb is soldered to it so for now I think it is fine. Anything from your experience I've missed please advise. thanks!

[vjmanzo]

Hmmmm…the magnetic pickups work only when the red button is out—have you tested this with a TRS cable? We want to make sure that magnetic pickup sounds are always coming through the Fishman—either through a standard mono 1/4” cable or on one end of a TRS to dual 1/4” unbalanced cable. Regardless, it sounds like your Fishman preamp is okay, so my guess is that the problem is with the jack and, specifically, with the ground connection coming from the red button. I forget exactly how this works, but the jack—especially on the early pre-refined Flys, can be a point of failure.

Ken mentioned that sometimes even a
1/4” cable with jacks made to looser tolerances can yield unreliable results with that jack—Parker ordered the TRS cable (linked in the parts list) from Pro Co.

[Floydwhammy]

Yes I Tried different mono cables with no change. When I use the Factory parker TRS cable the one cable output marked in pink/ red tape has no sound either humbuckers or piezo. However... the other output cable marked with blue tape gets full loud humbuckers when the stereo switch is pushed out but no piezo. But when I push the stereo switch in the humbuckers go badly distorted like a bad battery and super quiet barely hearable out of the amp. Then when I switch the piezo toggle switch over to piezo only mode the distorted humbuckers clean back up with no distortion but still stay barely audible through the amp. and there is no piezo still when I adjust the piezo volume pot up or down it makes no difference?
I could try to replace the output jack if there is a direct replacement for it yet. I didn't see one listed with the extra battery led activator tab on it.

[Floydwhammy]

Double checked the output jack again this time clipping leads onto the tabs before the output jack so to bypass it but alas still no piezo. But thanks for the reminder again. It was the first thing I checked months ago but only with a meter not actually bypassing it straight to an amp. Also just noticed different contact configurations on the ring and tip with the stereo/ mono switch in and out so the stereo mono switch appears to be working as I had previously expected.

[vjmanzo]

That’s all great news—seems like signs are pointing to something wrong with the preamp then, ya think?