GR-55 Hum Issues

Started by riggy, February 22, 2014, 09:34:54 AM

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riggy

Hi

Having finished modifying my Red Special we hoped that everything was okay but eventually decided that there must have been a loose earth somewhere so we went back and rechecked all of the original solder and all of the new solder.  We decided that we had done a good job but the hum still turned up.  This time we decided that the volume control felt and sounded like there was something not right.  So we brought a new control and made a good job of fitting that but the hum will still not go away.

The symptoms are:

When I plug the GR-55 Guitar Output into one of the AVT-150's the following happens no matter what patches or settings I change within the floorboard software:

Guitar/Mix/GK Select Switch:   

GK           >   Silence
Mix          >   Hum
Guitar      >   Hum

When I plug the GR-55 Line Out into the AVT-150 the following happens:

Guitar/Mix/GK Select Switch:

GK            >   Effected
Mix           >   Effected
Guitar       >   Silence

The difference with the Line Out route is that when I change the patches or settings to those which use the normal pickups I can recreate the hum.  I hope that makes sense.

So my questions are: Have I missed a setting or something blatantly obvious in getting my head round all of this?  Is there something possibly wrong with the modification to the guitar?  Is the GR-55 actually working properly?

Please have a look at the photo's - I haven't got any of the inside at the moment but I could try to take some if anybody needs to verify our work.

Thanks for reading, Rich


Elantric

#1
Fresh from the factory all GR55's will deliver identical results as you post above.

Read GR55 and follow procedures listed in
GR55 FAQ Top things to know thread.here
www.vguitarforums.com/smf/index.php?topic=4006.0




Jim Wintringham

If you look at old post...the hum issue is mentioned a lot. It seem to show up the most on the normal pickups, when using the amp/ distortion path. I use the cmos for distortion, and normal pickups set to 'bypass' in the structure page, if I want to use the 'guitar out' for normal pickups. Many players use a separate effect module for the normal pickups...if you want to use them. I switch between using the 'guitar out', or a completely separate path (1/4" cable)....into a Zoom G2 effects pedal, then into a Roland kc300 keyboard amp (4 channels input). You can also play with the amp/gain levels to reduce the hum.
Roland GR-55
Wechter Pathmaker PM 7354
Brian Moore i91.13 (China)
Zoom G2
Ventris Dual Reverb
Roland kc-300

Elantric

#3
Lets Tackle things in this order

Quote
When I plug the GR-55 Line Out into the AVT-150 the following happens with the Guitar/Mix/GK Select Switch:   

GK            >   Effected
Mix           >   Effected
Guitar       >   Silence



Correct - because ALL GR-55 FACTORY Patches ( with the exception of three: LEAD: 30-1, 30-2, 30-3) have a non functional "Guitar" position for the GK-3 three way switch.  The Normal Magnetic pickup Guitar signal path ( from Pin #7 on the 13 pin cable ) is intentionally disabled  / muted  -
Only Edited GR-55 in the USER patch area will provide a functional Guitar mounted "Guitar/Mix/GK" Select Switch on your 13 pin guitar :   

Details on how to make  Guitar/Mix/GK Select Switch work is here:
https://www.vguitarforums.com/smf/index.php?topic=3402.0


Quote
When I plug the GR-55 Guitar Output into one of the AVT-150's the following happens with the Guitar/Mix/GK Select Switch:   

Guitar/Mix/GK Select Switch:
GK           >   Silence
Mix          >   Hum
Guitar      >   Hum


Correct - because fresh out of the box the GR-55 "Guitar Out Jack" is disabled -

GR-55 Owners Manual
#17 MEMO  (page 54)
The GUITAR OUT jack can output the normal pickup sound and the sound of the modeling tone.
For example, you can make settings so that the normal pickup sound and the modeling tone sound will be played through a guitar amp, while the other synthesizer sounds will be played through the PA system connected to the OUTPUT jacks. For details, refer to System settings "GUITAR OUT Jack Settings (GUITAR OUT)" (p. 70).
For details on the parameters, refer to "GUITAR OUT" (p. 59). If the SYSTEM setting GUITAR OUT (p. 80) is set to anything other than "PATCH," this setting is ignored.

#20 MEMO  (page 71)
Changing the Output Sound from the GUITAR OUT Jack for Each Patch
1. Set the system parameter GUITAR OUT–SOURCE (p. 80) to "PATCH."
For details on setting the system parameters, refer to "Settings for the Entire GR-55 (SYSTEM)" (p. 69).
2. Set the master parameter GUITAR OUT–SOURCE (p. 59) to the setting you want to use.
For details on editing the master parameters, refer to "Patch Settings
(MASTER)" (p. 54).

• The setting of the GUITAR OUT jack does not affect the output from the OUTPUT jacks.
If you don't want the output from the GUITAR OUT jack to be included in the sound that's output from the OUTPUT jacks, you must separately set each of the patch's tone settings to "OFF."
• If the GUITAR OUT–SOURCE setting is "BOTH," the normal pickup sound and the modeling tone sound will be mixed.
• The OUTPUT SELECT (p. 70) setting does not apply to the sound that's output from the GUITAR OUT jack.



To understand all of your GR-55, follow procedures listed here:
GR55 FAQ Top things to know thread.here
www.vguitarforums.com/smf/index.php?topic=4006.0

gumtown

One thing to check, unplug the guitar GK cable - does the hum stop ?

If it does, the problem is quite likely either the guitar or the cable.

Has the guitar bridge & strings been grounded? You could check with a multimeter for continuity between guitar metal parts and the GR-55 case.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Fusion

The guitar mod is over my head but it does sort of sound an unground bridge on the guitar.
"Long ago in days of old when magic filled the air..."