GR-55 -Modification to use as multi effects with any guitar

Started by baratijas, October 04, 2011, 05:08:31 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.


The wiring looks fine, but I am concerned about your multimeter.  I would go out and get a new meter with an zero ohms audio bleep, that way you will not have to keep looking at the meter.


I know my meter is lousy, but if you are writing about a function where when 2 sensors are in contact with each other, 000 appear on the screen and the meter makes a bleep, then it has such a function that works. I checked point by point all the connections by applying one sensor to the tip jack solder, for example, and the other to the right switch solder connected to it with a wire, and I always got OOO and a bleep. I got as far as connecting the tip jack to the 7 pin connector on the GR motherboard this way. The same with the audio signal line from the 13 pin connector.  I always obtained zeros and a bleep, indicating contact.

The switch also seems to work properly, as it only let the signal through if the lever was in the right position.

So the only idea I have, is that some audio line component on the motherboard is defective. :( As I wrote, the strange thing is that with the reverb on, I can hear the instrument audio signal itself in wet version. I already thought it was a matter of settings, but it repeats on all presets, and after all, it is impossible to globally set the output of the wet signal alone. Unless I'm mistaken ?


Try doing a backup of your user patches to file,
 then initiate a "Factory Reset" on the GR-55,
then re-load your patches back in.

Sometimes the GR-55 can have a sticky moment of currupted data, requiring a reset.

Also try the User patches up near U98:0 to U99:3 as they are designed to work with the normal pickups,
 else you need to make a patch that enables the normal pickups,
 as most  of the factory GR-55 patches do not use normal pickup.
Free "GR-55 FloorBoard" editor software from


Unfortunately, it didn't help. I even did a factory reset twice just to be sure. Even after factory reset there are no normal pickup sounds under U98:1 to U99:3. You are probably writing about the bass version. However, I tried with Lead 30-2 "For normal PU L2". The factory preset works there so that Normal pickup plays there as long as I don't switch chorus block to bypass mode. Then only the Wet signal from the reverb can be heard. When I turn off reverb block, no audio can be heard at all. When I turn on chorus block back, then normal pickup plays again. However, when I decrease MOD Send function in chorus block the guitar goes quiet again.

I don't understand any of this :( I've only been using the SY1000 for a year and have kind of forgotten the GR55's handling, but it doesn't look to me like a problem with some setup error of mine. Since the audio signal sometimes plays, my DIY MOD itself must be correct, too. Do you have any more ideas how to solve this problem ?


What happens if the modified wiring is returned back to the original configuration,
 does the Normal pickup signal restore ?

May need to back track on the wiring to find out if that is causing the issue.
Does any any normal guitar signal exit the "Guitar Out" jack (when the settings for normal guitar out) ?

Is the GK guitar also plugged in the GK socket input, as without the GK guitar connected, no signal will pass through the extra input jack, if the GK Volume control is not there the level will always be "0" volume output.

Do you run an active device between your normal guitar to the extra input jack ?
That is because the Pin 7 input from the GK instrument runs at very low impedance (about 100 ohms), and the buffer preamp in the GK pickup converts the high impedance guiatr signal to boosted low impedance.

Free "GR-55 FloorBoard" editor software from


I solder so clumsily that I treat unsoldering it as a last resort. I'll probably end up doing that, though.

Guitar Out always works. Sticking with the previous example, it doesn't matter which effect blocks are on. Guitar Out always plays. In headphones I can hear the normal pickup only sometimes.

I test both audio track - jack and 13 pin. I connected both direct signal from Godin XTSA and Grand Custom (so both I guess after inside buffers) and Chapman Stick through a high impedance preamp/summator (Palmer Duetto or SFX SP2). In a previous setup, I connected these instruments via this route to return FX and they worked without any problem.