Adrian Belew Signature Fly Variax troubleshooting

[DFAssistant]

Hi everyone!

First timer here, someone I know has a Adrian Belew Signature Fly with a Variax issue that needs some help. First things first, I will say the owner of this has apparently plugged in this Fly into this Roland VG-99 system with the Power Regulator input and output connectors mixed up. So essentially, he got it backwards. First thing I can think of is that the unit itself is damaged and needs to be replaced, but I'm not sure how to check it in general. One thing I can say for certain is that the Roland VG-99 still works perfectly fine so my thought process is that the damage is on the Variax itself. I've done all of the basic trouble shooting like checking/changing out the battery and testing other guitars on the VG-99, but the more advanced troubleshooting I have no idea what/how to do... One other thing that comes in mind that the owner of this fly had to also at some point fix some issue with the tremolo.

If the Variax is completely dead... how would one go about replacing it?

Neither of us are great at the electrical engineer side of all of this so some guidance would be very much appreciated! Also, if more pictures are needed or any clarification is needed please let me know! I

Thanks for the help!

[mmmguitar]

Hi, @DFAssistant. I've PM'd you regarding getting into contact with Dennis Anesi.

Below is what is supposed to be the 13 pin map for the Belew:

If the owner plugged the "input" side of the breakout box sending +8V DC up pin 9 into the VG-99, the damage should be to the VG-99; and not the guitar. The output stage of the Belew breakout box doesn't send anything from pin 9 to the outboard 13 pin gear which would fry the Variax circuitry - So it would be like plugging a typical 13 pin cable between the guitar and synth unit (no power up pin 9 = no Variax mode when the rotary push-pull is switched to the "down" position).

The 9V battery for the Sustainiac circuit is isolated from the Variax circuit by design/necessity; and won't affect anything in the Variax signal path (which is):

Piezo saddles > RMC PolyDrive I > Variax circuitry > Variax knob A/B switch selecting between Variax and Sustainiac circuit outputs to PolyDrive pin 7 > PolyDrive pin 7 output at jack

Have you swapped a different 13 pin cable in between the guitar and breakout box to test the connection? When the guitar is plugged in to the VG-99, does the middle selector switch position on the guitar (with battery power off, Variax knob "up") output the processed RMC piezo signal via pin 7 ("Guitar input" on VG-99)? Can you open the breakout box and use a multimeter to confirm that there's continuity from the power output to pin 9 of the cable running from it to the guitar? Then, test that the power supply is indeed outputting 8V DC (the power supply is 2000mA 9V; in case you need to test a replacement - You can search "Line 6 PX-2 power supply" to track down a cheap/generic one).

Apologies if you've already done any of that - I'm just trying trying to rule everything else out. My hope is that it's merely the #9 pin in the cable, breakout box, or PolyDrive jack on the guitar which is dirty or damaged.

In the event the Variax board (or any Variax part, for that matter) needs to be replaced, the only option is to hunt down an old Variax guitar on the used market (the iteration used for the Belew was discontinued in 2011 or so). You could reach out to Line 6 or Full Compass regarding sourcing a replacement Variax mainboard P/N 35-00-0005 - But they're famously unhelpful concerning such items unless someone happens to find the exact part in a warehouse. The problem there is that I have never gotten a definitive answer as to which Variax board the Belew used (it appears to be a 700 series board; as the 300/600 series boards had a different PCB footprint, and the 500 boards I've seen had larger resistors and caps) - The one in my Belew isn't labeled with anything but the Line 6 logo and "Custom Rev B" (whereas the others I've seen were labeled 300,500, etc.)

Here's a photo of my working Variax board; in case comparing it to yours shows any components to be obviously damaged (click/save to enlarge):

And you can use a H1.5 key to remove the screws securing the power switch to the rear cavity cover and securing the inside corner of the Variax board to the guitar body.

Something which is kind of bugging me is that 8 pin connector unplugged and hanging out of the guitar while the Variax board and power switch are still mounted. Was that intentionally done in the course of troubleshooting, or was it unplugged when you took the cover off? The Variax mainboard appearing to be covered in dust in that last photo raises further questions.

[DFAssistant]

@mmmguitar Wow thanks for your all of your help! This definitely helps deepen my understand of this guitar because I have NO idea what I'm doing.

I'll try to answer all of the questions in order...

So we've tried another 13 pin cable between the guitar and the breakout box, but no connection there.

I'll be there today to double check if we're getting "Guitar Input" on the VG-99, but from what I'm being told... there was no "Guitar Input" on the VG-99.

We definitely have not opened the breakout box to confirm that there's continuity from the power output nor the power supply... will try to get to that asap.

Thanks for the picture of your Variax board as well, I'll definitely be using that to compare, yeah we're defintely hoping we don't have to go through finding a replacement Variax mainboard.

So the 8-pin connection was unplugged before I started helping out. I do know that the owner of the belew opened up the guitar before to troubleshoot a tremolo issue he had as well as he's tried to fix the variax issue before. But regardless, I'm glad you metioned the mainboard being covered in dust since I didn't notice that before... I'll double check with him on that today as well and it would be GREAT if that was just main issue... One quick thing from what I noticed too, but from what I've been told I don't think there's any PCB damage besides the dust I suppose...

I'll keep in touch with updates, but I'll be trying to go through a couple of tests with the first one being connecting that 8-pin... If that's truly the main issue for all of this... well... as long as it works I guess...

Thanks so much for your time and help so far!

[mmmguitar]

Thanks so much for your time and help so far!

You and the owner are doing me a huge favor by documenting this stuff - There are very few of these guitars in existence; so (if I may presume to speak on anyone's behalf) any little bit of hands-on discussion helps to ease the dread the few Belew owners scattered around the world feel at the prospect of having to troubleshoot or repair any of the crazy stuff under the hood.

[DFAssistant]

Update #1: So here's a few pictures of the innerworkings of this belew as well as a couple of pictures of the PCB as well. To my untrained eye, it doesn't seem like there's any vast differences to @mmmguitar's Variax board, but I'm not too confident in this analysis...

Another thing is there is "Guitar Input" on the VG-99. The Variax knob is "up" while the battery is off and we're getting a signal from the VG-99.

Regarding the floating 8-pin... after looking through the PCB and moving some things around to double check we have no idea where this 8-pin is supposed to go or if it's even supposed to be plugged into anything... It's a little strange but apparently it's been there for some time now.

Haven't checked the breakout box with a multimeter yet, trying the "simplier" troublingshooting things first. We also came to the realization that all of the 13-pin cables he has are quite old so we're going to try and get a new one and troubleshoot that.

[mmmguitar]

Everything in the guitar seems to be looking good. Hopefully it's a sign that the problem lies with the external power regulator or cable.

Regarding the floating 8-pin... after looking through the PCB and moving some things around to double check we have no idea where this 8-pin is supposed to go or if it's even supposed to be plugged into anything... It's a little strange but apparently it's been there for some time now.

It seems to be a red herring created by Dennis wiring the two Variax boards up differently. Note how the plug I circled in red (which is present on my Variax board) is absent from yours:

The bundle of wires going to the 8 pin connector are altogether missing from mine:

So it appears to be a quirk we've learned of, and can now safely ignore.

Another thing is there is "Guitar Input" on the VG-99. The Variax knob is "up" while the battery is off and we're getting a signal from the VG-99.

Good. Just to be clear: With the battery power switch on the guitar "on", everything in the five selector switch positions (neck, neck+piezo, piezo, piezo+bridge, bridge) gets sent to the VG-99; and it's strictly when pushing the Variax knob down to rout power to the board and the output signal down pin 7, while a 13 pin cable is ran from the guitar to the female jack on the breakout box/power regulator, the power supply plugged into the breakout box, and the box's internally connected 13 pin cable connected to the input of the VG-99, that there is no signal outputted from the Variax circuit once engaged and (presumably) powered? If so, we can move on to the next troubleshooting step of checking the power regulator/breakout box, and the power-carrying pin 9 of the 13 pin cable running from the breakout box to the guitar.

Below is the underside of my Belew power regulator/breakout box. The four phillips head screws holding the top and bottom of the box casing together need to be removed (don't worry about the H1.5 screws, yet):

With the phillips screws removed, the bottom of the box casing with the power supply PCB attached should be accessible:

On my box, three of the four H1.5 screws didn't want to unscrew, and the PCB appears to be mounted to a steel plate via more screws, and also hot-glued to the inside of the box casing So...we'll test for continuity from the topside of this assembly:

Using a multimeter set for continuity, I've attached one probe to pin 9 of a 13 pin cable, with the other end of the cable plugged into the box.

I've circled the terminal in the box which showed continuity with pin 9 at the other end of the cable when touched with the other probe:

If yours shows continuity, then that should give the cable and output stage sending the power up pin 9 a clean bill of health. Being as I haven't seen the interior of your box, I can't say whether plugging the powered end into the VG-99 burnt out any of the PCB components - Still, better the box than the guitar (I know Third Coast Guitar Repair in Chicago has fabricated replacement Belew power regulator boxes - Probably with Dennis' help; being as he's local to them). From there, you can begin testing for continuity between the power plug contacts and their solder points on the PCB, the solder points the capacitors are soldered to, etc.

I also thought to mention that, in the event you do (heavens forbid) happen to determine that the fault lies with the Variax circuitry itself, Partev Sarkissian in Los Angeles is likely the person Line 6 would have you send the guitar to (should Yamaha even approve it). You would basically log a support ticket with Line 6 and cross your fingers.

The hurdle with getting any internal Belew circuits serviced is that it requires either a single specialist (RIP Axel) or determining which components are faulty; before seeking out the entity in a position to deal with them: Alan Hoover at Maniac Music, Inc., Indianapolis is the Sustainiac tech support, Partev is Line 6, Richard McClish at RMC, Berkley would help out with the PolyDrive I and saddles, and Dennis Anesi is of course who fabricated the switching tone pot, tilted, replaced, or re-mounted the various PCB components as needed to fit the space constraints, and ordered/assembled the custom PCBs and various junctions and trim pots for the guitar in the course of assembling it all.

I haven't described or taken photos of the underside of the RMC PolyDrive PCB and jack, yet, because that thing is a nightmare to re-mount once you've removed the plastic nuts and screws used for the fancy-pants flush mounting (it's a three hand job); and I refuse to do it again unless I'm forced to repair or replace a component soldered there. Basically, you would repeat the steps of testing for pin 9 continuity that you did with the box: probe on the pin at one end of a cable plugged into the guitar, and the other probe on the PolyDrive PCB solder pad the Variax power wire is connected to (easier said than done, I know).

[DFAssistant]

Hey! Sorry for the disappearance! It's been crazy busy over here currently.

Update: We've opened up the breakout box and it seems like there's power coming through from the 9 pin of the cable... Video quality might be a bit bad, but it should be clear enough to get all of the values from the multi-meter.

But after this, since there's power coming through the regulator... what would be the next troublingshooting step?

https://streamable.com/idvz6x

Here's a video link to me and my co-worker testing out the voltages... Video will expire in two days though so I'll try to upload a new one after.

[mmmguitar]

what would be the next troubleshooting step?

Did you ever try a different power supply feeding the regulator/breakout box? I can confirm this one works (I bought one last year as a backup), and that a bad power supply will cause exactly what you're describing (now that continuity from the regulator to pin 9 of the male 13 pin cable end has been confirmed). If you happen to know anyone with older Line 6 gear (DL4, MM4, DM4, AM4, FM4, POD 2.0, PODXT), you can also borrow their PX-2 power supply for the test.

I'm willing to move forward with surgery photos illustrating how to confirm that the Variax's Freescale DSP56367 processor is receiving 500mA power, and how to confirm continuity between the contacts of the push-pull encoder Dennis used for the Variax knob to A/B which signal the PolyDrive outputs via pin 7 - But the Line 6 PX-2 (9v 2000mA) wall wart power supply should first be ruled out as what's causing the issue (if you did, I apologize for missing it).

[DFAssistant]

Actually that's a really good point, we have yet to actually try a different power supply. Yeah... let me try that before we have to do open heart surgery on the guitars and we'll probably get back to you in a few days whenever it comes... thanks again for all your help!

[DFAssistant]

Quick question...

"while a 13 pin cable is ran from the guitar to the female jack on the breakout box/power regulator, the power supply plugged into the breakout box, and the box's internally connected 13 pin cable connected to the input of the VG-99, that there is no signal outputted from the Variax circuit once engaged and (presumably) powered?"

Just in case, but what would be the next step for troubleshooting if there is signal with the Variax circuit engaged?

[mmmguitar]

Just in case, but what would be the next step for troubleshooting if there is signal with the Variax circuit engaged?

The signal would need to be described. Any outputted signal other than the expected Variax-processed piezo signal modeling various guitars could indicate a fault in the Variax board; which may necessitate either seeing if Line 6 would be willing to have one of their techs diagnose the issue (any of a ton of tiny components could be at fault), or trying to independently source a replacement board for the sake of further troubleshooting.

The Belew Fly outputs one of three circuits via pin 7 of the PolyDrive's 13 pin jack:

One is the active Sustainiac pickup /passive humbucker circuit in selector switch positions 1 and 5 (powered by onboard 9v battery),

the second is the RMC hexaphonic piezo preamp powered by the guitar synth unit in position 3 (with switch positions 2 and 4 being mono sums of the first two circuits in parallel via the onboard PolyDrive mixer),

and third is the externally powered Variax circuit engaged when the "model select" rotary pot is pushed "down" to output the Variax-processed piezo signal instead of the previous two circuits.

Per my understanding, the only issue afflicting this guitar which has been described is that engaging the Variax circuit by pushing the model-selector knob down (when it is presumably powered) outputs no signal. If there indeed is a fault we can infer to be limited to the Variax circuit by way of either the external power supply, the Variax mainboard, or the switch portion of the rotary push-pull encoder used to A/B between which signal is outputted via pin 7, the VG-99 should be receiving "normal guitar" input of the magnetic pickups and the RMC piezo with the Variax knob in the "up" position, and then no signal when the "Variax" knob is pushed down, and the guitar volume pot turned to 10.

If the synth unit's "normal" guitar input is receiving signal from the Variax circuit, it's a question of whether what is being recieved/outputted by the unit the expected, processed guitar sound, or something else?