The Parker Guitars Forum

General Discussion => TECH TALK => Topic started by: th_groove on December 01, 2017, 05:04:48 PM

Title: Flyer classic 1996 Piezo problem
Post by: th_groove on December 01, 2017, 05:04:48 PM
Hi everybody,
i got a parker fly from 1996 just a couple of days ago for a really decent price from a friend and former band mate who got it over 12 years ago second hand from someone who tried to add a midi pickup...therefore it may be modded in an unknown way.
At the moment the situation is as follows:
Scenario A: stereo-mono-switch out (stereo mode)
1. All mag PUs function as they should
2. PU-system-switch in solo mag or mixen mode and a signal comes to output Jack
3. Battery new, signal led flashes
4. PU-system-switch to piezo only - no signal at all at the output jack
Scenario B: stereo-mono-switch in (mono mode)
1. Just a very silent signal from the mags in PU-selector switched to mag only and mag+piezo (if cranked up volume on the amp nearly maximum, mag-volume and master volume seem to work - signal gets noticably louder or less while turning up and down)
2. Piezo is dead again
3. loud plop-noise is coming out while pressing stereo-mono-switch through output

The fishman electronics board has been replaced already without any improvement. I meassured for short circuits and correct signal path according to the wiring diagramms i've found and there seems to be no failure. But why the piezo doesn't work?

Any idea, what to check next, guys?

Regards from germany

Title: Re: Flyer classic 1996 Piezo problem
Post by: billy on December 05, 2017, 12:30:53 PM
Hi Tom-

Hard to say without knowing if the wiring is stock or modded.  I'm guessing it's been modded, even if by accident. Also not sure what diagrams you're referencing.

I'd check the piezo output trimmer first, because it's easy.  Make sure all the ribbon cables are seated properly (also easy)- there's a quick release on the white ribbon connectors on the pcb- release it and reseat the cables, then re-engage the cable lock. 

Check all the ribbon cables for any tears or breaks.  (This is my primary guess based on your description- I think there's a continuity problem with some kind of break or tear that is maybe not so easy to see.  It could just be a bad jack too.)  If there is a tear, you may be able to add wire jumpers.

Then check the switches and associated wiring.  Also be sure to check the piezo wiring/summing connections under the bridge.

If you still want to add midi, I'd probably just swap things over to the graphtech system.  (You can use the same piezo saddles and the midi part should be a lot simpler to do.)

There are people still looking for old parts here and there, so don't get into a sunk cost mentality.  You could recoup much of your investment by selling the parts that aren't broken.
Title: Re: Flyer classic 1996 Piezo problem
Post by: th_groove on December 05, 2017, 01:03:29 PM
Hey Billy,

thank you for your answer! I already feared that nobody had any suggestion.  :D

First thing to state: i just want my parker to funtion as it should originally - no midi and no unnecessary modification besides things to do for getting it back to work on all pu-systems.  8)

Compared to other standard fly classic models and to the wiring diagrams i found on several sites searching in the internet (even compared to the original wiring diagram provided by parker on their official site) there should be no modification - or at least it was completely re-modded after the mentioned midi upgrade that obviously didn't work the way it was intended.

But i can't find the broken link between piezo output entering the input of the fishman electronics and the output jack.

The first suggestion regarding the ribbons you mentioned i've tested first by myself without luck. I measured the wiring for broken lines on the ribbon, too. Every single wire has no measurable resistance - seem to be okay.

I checked switches next step and they seem to work as they should - signal goes the path it should according to the original wiring diagram (from parker site). Even the hole fishman electronics is replaced by a new part without any improvement.

The only test i didn't make untill now is trying to grab the signal along the signal path at critical points and send it directly to an amp. Would the piezo send a signal even without going through the fishman electronics at all? Just for test purposes regardless of the sound...

Maybe it is no electronic but a mechanic problem?

Maybe someone experienced such a behaviour (as described in my first post) on his/her own and could tell me what has been the broken part or how you fixed it?

Best regards
Title: Re: Flyer classic 1996 Piezo problem
Post by: billy on December 05, 2017, 02:14:06 PM
Hi Tom-

that was quick!  Glad to know it didn't just go out into the ether...  IMHO electrical issues are at some point a result of a mechanical failure.

With the old guitars, the issue is frequently related to the jack, pots, or ribbons.  With the newer models, the switches seem to be a more frequent failure point.

Given the experience you seem to have, I think your best approach is to trace the circuit.

If you have a small practice amp, you can make a signal tracer pretty easily.  (Any amp will work, but for the sake of minimizing already low risk to your stuff, a battery powered amp is the way to go.)

You use 1/2 of a guitar cord connected to your amp's input, set at a relatively low volume. Solder one side of a .47uf (or similar value) unpolarized capacitor to the line side, and the ground side goes to ground on the guitar. If you have a spare 6.35mm jack, use that instead and connect any guitar cord to it.

Then use the unconnected side of the capacitor to probe through the circuit, starting with the pup wires and follow it all the way through to the jack.  You should get some signal from all the pups, although the tone might not be great, and where it stops is likely your issue.  The cap is only needed to help prevent popping as you move through different connection points of the circuit.

You can use piezos without a preamp- the issue is the great disparity between the impedance of the mags vs the piezos.  The preamp basically buffers things to the same level, and it also tames some of the high end of the piezos.

It sounds to me like you're getting almost no signal to the jack, and the odds of two pcbs going bad the same way is pretty slim.   It could even be something as simple as someone unsoldering the ribbon from the jack and reconnecting it in the wrong orientation, though I doubt it.

So my money's still on a bad ribbon connection, either at the switch or the jack, but this approach should help you find it.  Keep us posted!
Title: Re: Flyer classic 1996 Piezo problem
Post by: th_groove on December 06, 2017, 01:07:16 PM
Hi Billy,

thank you very much for your help!

It took me a while but now i was able to trace the signal path thanks to your advice. With the help of this wiring diagram ( i was able to localize a bit more where the signal gets lost.

The piezo signal goes through OP4 of the fishman MC (i can grab it there and feed it into my amp - sounds not as bad as i first thought it would) and then in an unknown way disappears.
As far as i'm right in interpreting the wiring diagram before it enters OP3 (where it is not getting to at the moment) it has to pass the master volume.

Anyone to confirm this?

Whether i try to grab the signal at the master volume or at the MC there is no signal at all coming from the piezo.

Besides i checked all the ribbons and switches again with the help of a resistance meter to make sure the signal goes the way the wiring diagram suggests it should.
All the way from b6 and b7 (when in stereo mode) and even from b8 (the output of OP1) to the output jack is totally in function. Therefore the stereo-mono-switch seems to work properly and the signal comming from ribbon connector B is connected to the output. The same applies to all connections in between the master volume and the ribbon connector A on the board (i measured at the soldering joints). Again no broken wires.

So the core of the problem lies somewhere between the first stage of amplification in the fishman electronics and the stereo-mono-switch.
For i already installed a replacement board without any effect i focussed on the pot for volume and tone since it seem to control the MCs operation for sound control. But i have absolutely no idea how to test it correctly. The resistance of both paths of this double pot change measurably while turning them up and down (nearly 0 up to 10 Ohms both for tone and volume part). Again everything seems to be okay.

Well, i don't have any idea what to check next.

Best regards,
Title: Re: Flyer classic 1996 Piezo problem
Post by: billy on December 06, 2017, 08:32:21 PM
Hey Tom

Not sure how much I’m helping here but I was looking for that link for a while and couldn’t find it. Thanks for posting it!

Next step you could do one of two ways:

The first way would be to find the spec sheets for the ic’s and then measure voltages at each pin. (Just in case: Negative side of your meter goes to ground, and the other to the pin you want to test.) The voltage should be very close to what’s listed on the spec sheet. If not, then that should help you id a bad ic or an adjacent part. Replace and retest.

The other way would be to just start swapping the ic’s sinc there’s only three. Op amps are usually pretty robust, and iirc the chip that fails most often is the power converter. So imho it’s worth checking voltages before you just start swapping things.

Based on the latest info, I think your issue is not the master volume but either a bad op amp or it’s not getting what it needs from the converter ic. 

Just really weird to have two boards not working, and same symptoms. The op amp is obsolete but I think there’s others that work as good or better with the same pinout.  I believe you can still buy the converter chip new.
Title: Re: Flyer classic 1996 Piezo problem
Post by: th_groove on December 07, 2017, 07:14:30 PM
Hi Billy,
again thank you for your advice!
My problem is that i can't find any specs for the chips used by fishman and therefore i do not know what voltage each pin has to have by default. Do you have any source for reference?
The other aspect is that i don't believe in two boards having exactly the same type of defect  (since i already swapped it to another one without any effect). So it's really unlikely that the board is the source of error, right?

For i have to get out of bed in less than 4 hours and back to work i stop to think about for the moment.

Recommendations welcome!

Best regards,
Title: Re: Flyer classic 1996 Piezo problem
Post by: billy on December 08, 2017, 09:33:39 AM
No problem Tom- I know how it goes, sleepless nights and all. lol

I'm a little confused since it seems like you tested all the off board connections and parts? 

To be clear, I still think that a connection between the pcb and the off board parts is the issue, but I wouldn't rule out a pcb problem either. If it is a pcb issue, then almost definitely one of those two ic's.

So, if your voltages on the two main ic's check out, then you can concentrate on where the fault is on the remaining parts of the circuit. 

And yeah, if both pcb's behave with the same symptoms, then you can probably rule out a pcb issue. 

Doesn't hurt to do some checking anyway, good experience either way, but I probably wouldn't spend too much time beyond probing a few pins.

You can look up the datasheets on a component supplier site, google works too.

Here's the op amp (datasheet linked there):

And the inverter ic (there's variations but most have to do with size/packaging):

So, assuming the pcbs are fine, I'd concentrate on the connections to the switches, the pots, and the jack. 

Keep in mind that a defect in the ribbons can be very, very small and not necessarily a tear, though that's normally how they fail.  Sometimes you can get a conductive break near a solder connection that isn't a tear.

My best guess is still an issue with the switch or jack...

As I think about it, the switch might be miswired too, meaning the switch might have been swapped out with the wrong configuration. Note the factory/aftermarket switch logic JMS illustrated.

I'd probably remove the switch from the circuit entirely, and check it independently (relative to which logic).  Then if it checks out, wire it back in appropriately using your JMS schematic.
Title: Re: Flyer classic 1996 Piezo problem
Post by: th_groove on December 08, 2017, 04:03:28 PM
Hi Billy,

you're right, the ic's are standard models - i did a search for specs of the fishman board as a hole without luck, but sure, these ic's work on whatever board in the same way...but i didn't get this after 20 hours without sleep yesterday.  Seems to be due to the late night's partly breakdown of my mind, too...   :-\

You mentioned the switch - which works great for the mags  (switches them on and off the way it should by default except the fact that the piezo doesn't pass it) - and if i got the wiring right it just sends one or none of the amplified signals from each pu system to ground depending on position. So if i take it out of the circuit completely (unsolder it) both signals should be send to the output, right? This should be a very simple way to find out if there is any problem without having to care about the logic of the switch (at least till the next step).

The next thing i was able to rule out is the jack. There is no signal at its soldering connections and if i send a signal from another source into them they pass the cable into my amp without any problem.

For i measured every single pot for resistance (and its range) i'm pretty sure they all function as they should.

So what remains uncertain are the ribbons and the ic's on the board. The latter ones i will test first for i hope not having to wire point to point every single connection. Should this really be necessary i would better spend some money someone doing this annoying job for me.  ::)

Thanks for the links you shared, this should help a lot!

Title: Re: Flyer classic 1996 Piezo problem
Post by: billy on December 11, 2017, 03:05:37 PM
man, you're dedicated! 

Anyway, there's always the possibility the switch is the right one but doesn't work the way it should.   

Removing and testing it on its own is probably the quickest way to both verify that it works and also check the logic.

Worth testing the two other switches too, though I think they're simple enough that you don't have to desolder anything.

If you still can't find the issue after testing all the ribbons and switches, I'd probably convert it to the fishman powerchip or graphtech ghost.  It's fairly straightforward, though there are some things to consider, like the loss of a master vol, piezo tone, and what to do with an "extra" hole.
Title: Re: Flyer classic 1996 Piezo problem
Post by: JamieCrain on December 12, 2017, 08:07:01 PM
The pup switches are notoriously bad on Parkers. Poor design leading to quality issues. Try bypassing them and see what that reveals.
Title: Re: Flyer classic 1996 Piezo problem
Post by: Big Swifty on December 12, 2017, 08:11:37 PM
The pup switches are notoriously bad on Parkers. Poor design leading to quality issues. Try bypassing them and see what that reveals.


Dude, gross generalisations...

The switches on the DF series of guitars are pretty poor, no doubt about that.

The switches on the original Fly's are as good/better than most.

Title: Re: Flyer classic 1996 Piezo problem
Post by: JamieCrain on December 12, 2017, 09:49:27 PM
Ok fair point B.S. Can’t speak of the early models only the newer ones.

Parker must have changed the components at some stage. *All*switches in both my 2013 and 2015 guitars have failed including the extra one they sent me prior to closing shop. I don’t gig and treat my guitars like they are made of crystal so I know it’s not me that’s the problem.

I’ve repaired most of them but I will gradually swap them out. Thankfully it’s an easy job.