Concidering Graph Tech Ghost in Fly Deluxe

[mmmguitar]

As you can see, @Gregsaab, the footprint of the Powerchip board having changed over the years has resulted in some solder pads not corresponding with their placement as depicted in diagrams from different eras of production. This is why I've been referring to photos of your particular preamp board in terms of "this wire running from the underside of the bridge to the preamp must be performing this function", "this green wire running from the star-grounding lug to the preamp must be performing this function", etc.

Also, I apologize for the misunderstanding and subsequent confusion regarding the color codes of the Ghost saddle leads: I was unaware they had updated their color codes to white=hot and black=ground. Given they use black as the designated ground for their other modular components, it makes sense. It unfortunately places the Parker retrofit guide yet another step out-of-date.

[Gregsaab]

I removed the tone knob to give easier access while drilling and I enlarged the existing channel to 3/8”. Realizing how fishing each connector through would progressively more difficult, I decided to fish all wires through in one fell swoop. I taped them all onto some dental floss and pulled them all through at the same time.

[Gregsaab]

I split the pre-existing black wire so I can just splice the black Ghost summed output to one half and solder the other half to the common ground. No reason to unsolder the wire from the two spots on the pcb just to redo it with a new wire.

[mmmguitar]

I split the pre-existing black wire so I can just splice the black Ghost summed output to one half and solder the other half to the common ground. No reason to unsolder the wire from the two spots on the pcb just to redo it with a new wire.

Agreed! I'm glad you had enough to work with.

[Gregsaab]

I’m hypothetically down to my last solder point (hard to focus with 4 kids!), but I want to verify it before I do it.

The green wire next to the board’s gnd (black lead) seems to be the common ground - the ghost’s hot (white) should just be soldered to common ground?

[mmmguitar]

The green wire next to the board’s gnd (black lead) seems to be the common ground - the ghost’s hot (white) should just be soldered to common ground?

Assuming you've clipped the one black wire running from the underside of the trem to the input of the Powerchip board, you can solder the summed Ghost hot wire to that black wire going to the Powerchip. The summed Ghost ground wire should be soldered to the same pad the green ground wire on the Powerchip board is connected to. The remaining half of the black wire soldered to the underside of the bridge should be connected to whatever grounding point it can reach.

[Gregsaab]

The remaining half of the black wire soldered to the underside of the bridge should be connected to whatever grounding point it can reach.

I soldered that right to that anchor:

[Gregsaab]

So, given that the white summed lead should be soldered to the termimal where the green wire is soldered, I should just be able to solder the white summed lead to the aforementioned ground anchor, correct?

[mmmguitar]

@Gregsaab, the summed white lead should be joined to the black wire going to the Powerchip which you clipped (EDIT: I unknowingly caused Greg a headache by directing him to do this without knowing that his wire was a shielded single conductor; which resulted in his piezo signal being shorted to ground when spliced in to it). The summed black/ground wire from the Ghost summing board should be soldered to the same pad as the green ground wire on the pad adjacent to the black one (illustrated below as "preamp ground").

In light of the unnecessary confusion caused by the various Powerchip iterations in the diagrams we have, and having only the underside of the board visible when retrofitting different brands of saddles, I've time-traveled to the future of 1998 to retrieve the following high quality illustration:

[Gregsaab]

Decided to quickly test before making final solder. Got it all strung up, flipped to piezo only, held the last wire on the board’s terminal and, alas, no sound

I have the black summed saddle wire grounded onto the common ground anchor, have the black Ghost summed wire soldered on the bottom-far right of the board, and was touching the summed white wire to the terminal directly left of that. Have reversed the summed connector several times.

I read on a different forum that you need to scratch off a layer somewhere on the bridge to allow for proper ground:
Edit: here https://forum.fractalaudio.com/threads/ ... st-1278266

Is there anything I’m missing?

Edit: pulled the ol’ multimeter out — the black summed output is somehow shorted to the common ground

[mmmguitar]

@Gregsaab, for what it’s worth, I never had to scrape any of the black finish off the ball end-retainers in my Fly trems. You can test for continuity between one of the strings and the underside of the bridge to see if this is necessary.

Also, the preamp will interrupt measured signal continuity before and after in the signal chain; and can potentially result in chasing a shorting gremlin where there isn’t one when troubleshooting.

Does the mag/mix section of the switch for the preamp output work independent of the piezo signal - Or is it all being shorted to ground?

[Gregsaab]

I thought that these two terminals are equivalent, but they are not. Terminal “A” is a ground. Should the summed output be soldered to “B”?

Edit: ok, so I missed the fact that the black wire going from the bridge to the board is shielded, with the inner being the actual signal and the outer being the ground.

Now that I understand that, I feel like the absolutely easiest install is simply to solder the ghost summing board directly to the existing summing board (and ground next to it). Then the existing black wire (the one that I clipped) would do exactly what you need it to.

[mmmguitar]

I missed the fact that the black wire going from the bridge to the board is shielded, with the inner being the actual signal and the outer being the ground.

Apologies for any unnecessary confusion I’ve caused to do with this: The illustration I mocked up is for the Powerchip wiring assembly I took out of my 2011 Supreme, which had a single conductor black wire running from the underside of the bridge to the signal input of the preamp, and seemingly without the shield shorting your “B” connection (I've updated the illustration to include it). Being as I replaced the entire assembly with new pots/switches/preamp/etc., some of what you’re encountering in the course of isolating connections is surprising to me (which is why I said at the start that “we’ll be writing it together”).

Edit: A photo of the isolated piezo sum board/string ground "tracks" I requested was attached below by Greg; proving that his initial instinct to repurpose the underside of the bridge by soldering the Graph Tech sum connections to them would have been functionally correct.

[Gregsaab]

Another thing puzzling me is how that shielded wire was soldered to the underside of the bridge - Was there a track the Fishman element leads were summed to which was isolated from a section the wire shield was soldered to?

Like so:

So I believe I could have just summed the Ghost, then soldered the output leads directly to that. No drilling, minimal soldering. I really wish I didn’t split that shielded wire.

Edit:
Verified piezo functionality when touching the white summed output to terminal “B”.

Trying to figure out what I want to do. It is most appealing to me to do the following:
1. Splice the original black wire back together
2. Pull all of the ghost wires back into the spring cavity
3. Solder the summed ghost leads directly into the bridge summing board & ground terminal.

However, it is a bit more work than just soldering the remaining white lead into the shielded black wire’s positive lead.

[mmmguitar]

It is a bit more work than just soldering the remaining white lead into the shielded black wire’s positive lead.

Whatever you decide on: Between the photos and other efforts you’ve made to document your troubleshooting, this is the most firsthand info I’ve seen published on retrofitting Graphtech saddles with the Fishman preamp; and the patience you’ve expressed to do with the surprises is noted.

In trying to make sense of why the official Parker retrofit guide wasn’t written with your preferred steps in mind, I can only assume that there was a mandate to move away from the “summing board” altogether, in favor of emphasizing the modular element of the Ghost saddles requiring they be summed within the control cavity. Edit: I've gone through and updated posts of mine to be more in line with reality, for the sake of whoever else needs to perform this retrofit.

[Gregsaab]

I finished the job! It sounds great and these saddles have noticeably less friction than the USM variants.

I ended up soldering the Ghost summed output to the pre-existing, shielded black wire that was still soldered onto the board. The black Ghost output was soldered to the shielding ground and the white output to the inner core. I used shrink wrap over the core to maintain good separation, then soldered the outer shielding, then shrink wrap again.

I think that it may be useful to offer multiple solutions for the install. As previously mentioned, I think the absolute easiest install is to leave the Ghost summing board in the spring cavity and just solder the output directly to the existing summing board (and ground) on the bridge.

Thank you @mmmguitar for all of your help and patience, it much appreciated. I hope this thread proves useful for future DIYers.