98 mahogany classic very faint piezo

[Bowen748]

Hello everyone.

I’m set up in stereo with 2 amps, button out.
This guitar has mags, but the piezo is really faint. Both are accompanied by a high pitch feed back type sound. Almost same frequency as the beep on my continuity tester.

I have 2 ribbon output jack assemblies and both sound the same.
I tried the red stuff on the switch with no change.

I don’t know how to test the switches with a multimeter.
Any ideas on the next thing?

I have a short 30 second video it’s 3 MB if anyone has an idea about posting it, let me know.

[Bowen748]

[KenanJ]

Hey @Bowen748 ,

This happened to me, the problem was that the 9V battery was dead or defectual, I know it looks dumb but maybe try hooking up a fresh 9V battery?

Cheers

[Bowen748]

I REALLY hope that’s the case.

I only tested the one that’s in it by mouth.

I’ll put a fresh Duracell in and let you know.

[Bowen748]

Wishful thinking. It sounds like the low batter sound. But my battery is good.

I had a 96’ for a good long time and this 98 for about 10, both mahogany.

I am familiar with the batter requirement’s .

My battery light flashes strong and goes out as it should.

[vjmanzo]

Does adjusting the trim pot on the preamp change the noise level?

[Bowen748]

Yes, it does.

[vjmanzo]

Okay—that’s good.

Does the piezo come through in mono/single channel?

I have had this issue once before when splitting the signals to two amps. The problem was that I while using a lower-quality TRS cable. In my case, I switched the cable for one made by ProCo and it solved the problem.

I seem to recall some issue with certain cables and the jack on certain Flys—helpful, right? I’ll check my notes, but maybe give that a try?

[Bowen748]

Cables are working on other guitars just fine.

There is a cable insecurity that comes with owning these.

I do remember taking it to a couple shops for clues with the same problems on their benches.

When I was putting in the replacement jack/ribbon assembly and plugged in with the guts hanging out I thought it was working fine and when I got everything put back in it was screwy again..

I’ll recheck and let you know. Thanks for the clues.

[vjmanzo]

Ooof—puzzling.

Okay—you’ve ruled out that the power is okay. You also said you tried two sets of flex PCBs and they’re both doing this, so—assuming there are no tears in both of the flex PCBs—I think that only leaves the preamp, the jack, and the red switch.

[Bowen748]

I should have post this pic in my previous post when I mentioned having 2 “ribbon output jack assemblies.”

I definitely wasn’t naming it properly.

I have 2 of what i have pictured. Ribbon, jack, button, and piezo volume/tone.

I think what I’ve learned is that if both of them are acting the same way the problem is with the preamp.

[vjmanzo]

I think what I’ve learned is that if both of them are acting the same way the problem is with the preamp.

Got it—yes, that makes sense and that’s what I would think too. Not sure where that leaves us in terms of options—do you have another preamp?

[Bowen748]

Yeah, I think I’ll have to get my hands on an acoustic-phonic and give it try. Maybe the hexpander too.

I found a lot of rich information on here already when I searched “Acousti-Phonic”, especially by @mmmguitar.
In an old post he mentions residing in the same state as I.

My imagination when wild when I read that. Like, there’s an actual chance my neighbor is @mmmguitar . Lol
That would be fricken awesome!

[vjmanzo]

[billy]

There is a voltage regulator chip on the original preamp boards that sometimes (rarely) goes bad. It will either not work at all or create a high pitch whine.

I think I have one of those ic’s in my stash of parts and I could swap it for you- just cover postage to and from for the pcb. The ic was less than $1-2. I don’t have a good way to test it though, none of my flys have the original electronics these days.

Failing that I can check my notes about which ic it is and maybe someone local with surface mount repair skills can do it for you.

[mmmguitar]

there’s an actual chance my neighbor is @mmmguitar . Lol
That would be fricken awesome!

I'm afraid I moved to a different time zone last April. Still, I'll try to be as neighborly as I can.

[Bowen748]

There is a voltage regulator chip on the original preamp boards that sometimes (rarely) goes bad. It will either not work at all or create a high pitch whine.

I think I have one of those ic’s in my stash of parts and I could swap it for you- just cover postage to and from for the pcb. The ic was less than $1-2. I don’t have a good way to test it though, none of my flys have the original electronics these days.

Failing that I can check my notes about which ic it is and maybe someone local with surface mount repair skills can do it for you.

Thank you SO much! @billy I was just digging into the Parker Bulletin for possible ghost install and now I'm zoomed in to the schematic.

Do you think it's the (partially covered by the ribbon connector) LTC1044? lol

[vjmanzo]

Do you think it's the (partially covered by the ribbon connector) LTC1044?

I hope it is the LTC1044 because we have a few instances of that being fixed in these posts.

[Bowen748]

I just ordered a 10 pack!

I will let you all know how it goes.

Thank you guys so much for getting me on your level! Its been a HUGE downer not having this amazing thing for several years.

[Bowen748]

Micro hack-saw!

Instead of trying to desolder 8 pins simultaneously, I serrated a razor blade and was able to saw through the pins cleanly. Now I can desolder each remaining lead one at a time.

Before I came up with that removal technique I tried using just a nail clipper but was only able to get the 4 corner pins snipped safely.

Also tried breaking it to expose more of the pins to snip.

That’s why the old LTC looks jacked up.

I wish I knew what devices are laying around at the thrift store with LTC1044s i could harvest.