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Fernandes Sustainer Static/dirty Sound?


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Hi there, I've come across this message board from finding that impressive DIY sustainer thread below on a Google search so I hope somebody here can help me because I don't know where else to ask.

I have very limited knowledge and electronics and I recentely bought an old Fernandes Revolver Guitar off ebay that has the old 1.0A model Fernandes Sustainer circuit.

It works fine when set on the bridge EMG pickup, but when I set the selector to either middle or top position (neck pickup/sustainer humbucker) sound will be filled with a lot of hiss, crackle, missed signals (hit a string and sometimes it will skip) or at othertimes it will have a lot of crunch (like bad/ugly distortion/overdrive).

I've never had one of these before and I don't know what's going on with it. I've taken a look inside and all wires and solder points seem clean. I noticed that on the sustainer board itself there are three little pots.

The sustainer documentation I can find online says these are the :

FDG - Output control for the neck pickup (driver). Set it to match the output of the middle or bridge pickup

VBC (vibration control) - Turn clockwise to increase the sustainers attack

AGC - Sustainer gain control, set to 10 if possible, if you get feedback turn it counterclockwise until the feedback stops.

Now the problem when I look at these is that the FDG pot has the plastic gnarled off on it so it it's difficult to turn unless I pull at the metal edges with a pick and even then it looks like it may be jammed. Could this be the problem? I'm not sure what the description is supposed to mean: "t to match the output of the middle or bridge pickup"

The attack and gain seem very weak and slow also (from what I've seen from sustainer demo videos) and I've tried both the VBC pots and the AGC pots as well as fresh batteries and I can't seem to get it to grab the strings like I've seen and heard in the video.

Anyway, those are secondary concerns because right now, I can't use the neck/middle pickups at all (when sustainer is off) because they are full of so much interferrence and static and wierd crunch and skipping and otherwise very very dirty sound that instantly disappears when I switch to the bridge pickup so the problem must be in the neck or part of the sustainer circuit board. I noticed when I pulled the board away from the bunched up wires in the guitar, some of the static cleared but there was still plenty of it.

Any ideas what's wrong or how I can fix this? I can post pics if neccessary. The tech at the local shop doens't really know anything about the sustainer or solid circuits like the sustainer's printed circuit board so he can't really help me.

Edited by Spare-Flair
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Hi there...Spare-Flair...welcome to Project Guitar!!!

First...I have never seen a Fernandes Sustainer up close and would be very interested. I have studied the patents and the like but there have been a few models. I certainly know how it works in general terms and come across a few problems like you mention in building my own designs

Pic's would really help I think. The driver, control cavity and the pickup layout.

I posted a couple of recent posts about the problems of EMI recently on the sustainer thread (page 77). I'm not sure how much you know about this device, but it is kind of unique with it's own set of difficulties...

It sounds as if it has been customized. The EMG does not sound standard. How many batteries are on board. EMG's are Active so require power, as do the other pickups...the sustainer itself drains a lot of current. At one stage Fernandes were running their sustainer on two batteries, without the EMG!

So, with the sustainer off...the circuit will still be running to preamp the neck and middle pickup. These are disabled when the sustainer is running. I take it with the Sustainer on, you don't get this noise but the performance is poor?

It certainly sounds like EMI (ElectroMagnetic Interferance) in part. The sustainer is a device that by it's nature gives of quite a bit of EMI. The EMI is generated by the driver coil but also exists in the wires to the driver (which are just extentions of the coil, right) so that if these leads are in close proximity to the pickup electronics, they will pick up this signal like sensitive aerials. So, by moving the circuit board...you are changing this proximity to the guitars wiring creating this change. Sheilding is not really enough to protect it. Let's see how this is wired in.

Obviously, someone has tried to address the problem by adjusting the gain pot that is damaged. It could be that this trim pot is damaged and may even need replacing. The EMG may have proved way too powerful to get a true balance. This FDG pot will be the active neck's preamp gain control...if this is damaged you will be experiencing preamp problems resulting in the effects described also.

So...it's a complicated problem. It could be something as simple as changing this pot...or it could relate to the modifications that have been made to the guitar when the EMG was installed. It could also be a side-effect of the nature of the sustaining device (I'm not sure how much of the drive circuit is still active when it is "off", for instance). The likelyhood is that it is a combination of problems and is going to take a bit of trouble shooting.

Out of interest...can you see numbers on the chips on the board? This may give a clue as to how they are preamping the thing. The other thing is that you mention a video...where is that? You know better to believe promotional vids I hope. The fact is that the sustainer can work well in an ideal set up and a new battery with someone with a bit of practice. Your setup sounds as if it needs some tweaking to get that kind of response. The driver needs to be very close to the pickup, the action low and consistant and the bridge pickup height adjusted pretty high too for optimal results.

Anyway...post some more details...and I'll think about it a little more...sorry I have no simple answer yet... pete :D

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