Author Topic: VG-99 - DIY Mono FX Loop Insert for Normal Guitar PU feed.  (Read 4554 times)

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Offline Elantric

VG-99 - DIY Mono FX Loop Insert for Normal Guitar PU feed.
« on: March 07, 2008, 12:28:36 PM »
Its time to void the warranty and re-explore the old VG-88 FX Loop mod and implement this  to the VG-99.


Basically you reroute a few wires inside the VG-99 then it allows you to use your normal guitar PU's to send its signal out the rear "Guitar OUT" to feed Boutique pedals that return back into the VG-99 via the Rear Guitar INPUT jack.

True - no COSM guitars, but it adds a lot of flexibility 0  when you simply must have your favorite wah wah or fuzz face, or Whammy Pedal, or ??

I'll post instructions on how to do this to the VG-99 - its for everyone except Davor ;)

The format will resemble the existing doc for the VG-88
=================
Excerpt from the VG-88 FX Loop Instructions - (see attached download)

The Roland VG-88 does not allow you to take the dry guitar signal from its guitar output port, process
it externally, and bring it back in via the guitar input port. It will let you either use the output port or
the input port but not both simultaneously.
This rework instruction is for the Roland VG-88 only (both versions 1 and 2). It allows you to take the
¼” guitar output signal (from the VG-88) to an external effects processor and bring the processed
signal back into the ¼” guitar input jack the VG-88. This processed guitar signal coming back into the
VG-88 is received as a mono signal.
If after doing this modification you want the VG-88 to carry the standard magnetic pickup signal as
before, without any processing of that signal, then you will need to put a ¼” cable between the guitar
input and output of the VG-88. You need to do this since the signal from your normal pickups is no
longer directly going to the internal VG-88 processor.
Disclaimer
The author of this paper is not responsible for any damage/injury to the equipment or to the party that
performs this rework. Please follow all safety precautions or have a professional perform this rework.
You should have good soldering skills. If you don’t have clean shiny solder connections
then your signal quality can be poor. Using proper tools and skills for the job will save you time and
possibly prevent you from damaging your system. Discussion of proper use of tools and skills is
beyond the scope of this paper.
Warranties are void if you perform unauthorized work on your system. Even though this rework is
reversible there are always tell tale signs that the system was modified; so if your unit is still under
warranty think twice before you do this mod.
Needed Rework Tools
1) Soldering Iron (Improper temperature and use can damage components)
2) Solder wire with resin core
3) Flux paste or pen
4) Wire clippers
5) Tweezers
6) 2 to 3” of common wire with plastic/rubber cover
7) Philips screw driver (make sure it properly fits the screw else you will strip the screw head).
8 ) Wrench set, or Adjustable wrench (or pliers)
9) Table Mounted Magnifying glass (if needed due to aging eyes)
10) Rubbing alcohol + cotton swab (to clean soldered areas)
« Last Edit: April 29, 2015, 01:56:50 PM by Elantric »

Offline Elantric

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #1 on: March 07, 2008, 12:44:29 PM »
Heres the schematic of the Guitar IN and Guitar OUT Jack area of the VG-99 ( sorry for the poor quality)
« Last Edit: March 07, 2008, 01:14:28 PM by sustainiac »

mesaman

  • Guest
Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #2 on: February 01, 2009, 03:12:20 PM »
Any luck/progress with instructions for doing this on the 99?

Offline Elantric

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #3 on: February 01, 2009, 10:41:24 PM »
I got sidetracked - yes this loop mod is still "doable" this aspect of the VG-99 design is identical to the VG-88 - see 1st post above for the MOD instructions. - just have not had time to dive in and do this on my VG-99.

Maybe soon.


Offline Dukemaster

If I performed this mod and wanted to blend the dry guitar with the VG-99, how can that be done if I need to plug the Guitar Out to the Guitar In on the back?  The mod would eliminate that part of it right?  I am further confused as to why this is necessary because I can take the Guitar Out (Which is dry) from the VG-99 and run it to a seperate channel on the mixer.  I could add whatever effects I wanted before or after the mixer so why would I need to go back into the VG-99?
« Last Edit: May 20, 2009, 07:40:02 PM by Dukemaster »

Offline Elantric

Quote
so why would I need to go back into the VG-99?

To use the COSM Amp sims and FX with your standard Magnetic pickups - and be able to switch in and out  the hex COSM guitar patches  - all self contained , no external mixer required.

See the VG-99 Flow Chart here:
http://www.vguitarforums.com/smf/index.php?action=dlattach;topic=1485.0;attach=1612


After the VG-99 Mag PU "FX Insert" mod - you will now be able to connect your GK-3A equipped guitar to the VG-99 using the typical 13 pin cable, then when you select the "Normal Guitar" position on the GK-3A's "Guitar/ mix/ Synth" switch -  you may employ third party guitar stomp boxes on the Mag PU signal path - after the mod you will use the VG-99 "Guitar Out" jack as an FX Send - to feed the Mag P.U. signal ( which connects to the VG-99 via the the 13 pin cable) to your assortment of guitar stomp boxes (Keely Compresser, Fultone OCD,E-H Memory man, Line6 M13, etc.)  then the last stomp box the chain can now be routed back into the VG-99's 1/4" "Guitar Input" jack - - which after the modification to the internal VG-99 routing,  is now an "FX Return  for further VG-99 processing like COSM Amp sims and delays and reverbs and EQ.

To see the signal flow:

Here's the stock VG-99 Signal Flow:




Here's the modified VG-99 Signal Flow after the "FX Insert" mod:





Its a simple mod - move 2 internal connections ( cut & jumper) on a PC board.

The Caveat - the external FX can not be used on the hexaphonic signals ( COSM Guitar)

They only function on the standard Magnetic Pickup's signal path prior to hitting the VG-99's COSM Amp Sims.
« Last Edit: March 31, 2014, 01:46:26 PM by Elantric »

Offline MCK

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #6 on: February 19, 2010, 02:54:06 AM »
I'm trying to do the reverse. I would like to connect the VG99 in my serial effect loop on a tube amp and use the VG99 as a multi-effect generator. Is this possible? So in this scenario I do not connect a hex pickup guitar at all. Only connections to the VG99 are the Guitar In coming from effect send on the tube amp and Guitar Out going to the effect return on the tube amp. Trying to get this to work with no success so far. Any ideas? Thanks

Online admsustainiac

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #7 on: February 19, 2010, 03:25:52 AM »
Quote
I would like to connect the VG99 in my serial effect loop on a tube amp and use the VG99 as a multi-effect processor . . . . .Trying to get this to work with no success so far. Any ideas?


This can work,

First check that the VG-99 is passing audio sent into the 1/4" Guitar input.


BAsically the steps are:

1) Plug a Normal Electric Guitar into the VG-99  1/4" Guitar INPUT ) on rear panel

2) On the VG-99 , Press the "Modeling Type" switch.

3) Then press the Page button 6 times - which takes you to Page 6 and there's two knobs for mixing the "COSM Gtr" and "Normal PU" sound.

4) The "Normal PU" is the signal fed into the rear "GUITAR INPUT" jack. By default the "Normal PU" Level control is set to zero, turn it up to taste, as you should begin to hear your Guitar you plugged in at Step #1

5) Save your setting by writing to the patch in the User Patch Range.


Once you have accomplished steps #1 thru #5, and can hear your normal Electric Guitar signal at the VG-99 Outputs /Headphone, then proceed to create a "Dry Patch" with Unity Gain in All FX sections. this may take time! Then run a cable from the Amp FX Send to the VG-99 1/4" Guitar Input, and feed the VG-99 Main Left Out into the Amps FX Return.

Use the VG-99's internal Metering system to check your Gain Structure, and start tweaking to taste.

IMPORTANT NOTE:

Now to your Amp's  FX Loop. - Not all FX loops are created equal.  You will need one with both a variable Send Level control, and a variable Return Level control .  This type first appeared on Paul Rivera designed 1984 Fender Concert Amps, and still exists on "Evil Twin"  - check your rear panel. The circuit is in the lower left:

 


Basically you will need to attenuate your Guitar Amp's FX Send down to -30db Instrument level , so it can safely feed the VG-99 Guitar Input without clipping. 

If you do not have a separate variable FX Send level pot and variable FX Return level pot on your Guitar amp, then its likely the 4 cable method for connecting External DSP processors  will NOT work



« Last Edit: March 31, 2014, 03:43:50 PM by Elantric »

Online admsustainiac

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #8 on: February 19, 2010, 03:37:11 AM »
Another "Trick" uses the VG-99 standalone, with a bunch of cables.

Run the VG-99 Right Output into the VG-99's Guitar INPUT, and create self oscillation, cascading feedback, flanging, etc. - Bill Ruppert taught me that trick!

Offline MCK

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #9 on: February 19, 2010, 08:40:42 AM »

Once you have accomplished steps #1 thru #5, and can hear your normal Electric Guitar signal at the VG-99 Outputs /Headphone, then proceed to create a "Dry Patch" with Unity Gain in All FX sections. this may take time! Then run a cable form the Amp FX Send to the VG-99 1/4" Guitar Input, and feed the VG-99 Main Left Out into the Amps FX Return.


Thanks much for that. Will try and report. So just to make sure I understand this right... I see that I am to use the VG99 out rather than the Guitar Out. What is the Guitar Out jack for then? I'm still not following that one. When I route my serial effect loop through Guitar In & out on the VG99 I get good audio passthrough so there is definitely some connection between the VG99 guitar in & out jacks. Is that what it is, simply a pass through so VG99 can get the signal and process it to eventually feed out of Sub or Main Out? Thanks for the clarification.

Online admsustainiac

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #10 on: February 19, 2010, 09:04:08 AM »
Skip the VG-99's Guitar OUT jack.

Quote
What is the Guitar Out jack for then?
When you use the external GK-3A, and 13pin cable connected to VG-99 13 pin input, the VG-99's "Guitar Out" jack simply outputs a dry Unprocessed version of whatever signal you are feeding the GK-3A's 1/4" "Guitar Input", typically your Normal Guitar's Mag pickups.

Most folks might have a Strat with external GK-3A  - INSTALLED PROPERLY!, and the short 1/4" inch cable is installed between the Strat's normal output jack, and GK-3A's  1/4" Guitar Input. This is a crucial component as it provides a signal path to the VG-99 for your Normal pickups via the 13 pin cable,  and it effectively grounds the GK-3A to your guitar strings, to control noise, and safely protect you from shock hazards. .

If you meet the conditions above, the VG-99's "Guitar Out" jack allows you to feed the stock Strat pickups to your Vox AC30, or other guitar Amp/gear.





« Last Edit: February 19, 2010, 12:17:12 PM by Elantric »

Offline MCK

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #11 on: February 19, 2010, 09:11:32 AM »
Super. Understood. Thanks!

Online aliensporebomb

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #12 on: February 19, 2010, 07:48:02 PM »
Another "Trick" uses the VG-99 standalone, with a bunch of cables.

Run the VG-99 Right Output into the VG-99's Guitar INPUT, and create self oscillation, cascading feedback, flanging, etc. - Bill Ruppert taught me that trick!

Oh that's an interesting trick for sure.  What else did that guy figure out that we didn't?  Crimeny. 
"this is aliensporebomb" - my instrumental debut with the vg99 now on itunes: http://itunes.apple.com/us/album/this-is-aliensporebomb/id391880218
More online at http://www.aliensporebomb.com/

My VG-99 based music projects:
http://www.aliensporebomb.com/

Offline Elantric

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #13 on: February 19, 2010, 07:55:19 PM »
Quote
What else did that guy figure out that we didn't?  Crimeny. 


Well it helps that Bill owns TWO VG-99s, and uses one at his Day gig - session player.

Offline MCK

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #14 on: February 20, 2010, 08:14:01 AM »
Ok. Tried and proved this method to work. Thanks much for the information. This particular amp I was trying it does not have the Send / Return level controls so I guess its not a good candidate but still was a nice experiment. I can see myself occasionally treating the VG99 as a glorified guitar effects processor in this manner... Definitely an overkill but hey. Its fun to experiment.

Online aliensporebomb

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #15 on: February 20, 2010, 11:02:43 PM »

Well it helps that Bill owns TWO VG-99s, and uses one at his Day gig - session player.

Yeah.  I've also found that sometimes the best sounds I've discovered on the VG were done so accidentally.
Like, just messing around with settings and suddenly I go "whoa, what was that?".

"this is aliensporebomb" - my instrumental debut with the vg99 now on itunes: http://itunes.apple.com/us/album/this-is-aliensporebomb/id391880218
More online at http://www.aliensporebomb.com/

My VG-99 based music projects:
http://www.aliensporebomb.com/

Online aliensporebomb

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #16 on: February 23, 2010, 04:51:20 PM »
I still want Bill to use a US-20 to hook two VG-99 together then run FOUR virtual GR300s.  THICK as a brick!
"this is aliensporebomb" - my instrumental debut with the vg99 now on itunes: http://itunes.apple.com/us/album/this-is-aliensporebomb/id391880218
More online at http://www.aliensporebomb.com/

My VG-99 based music projects:
http://www.aliensporebomb.com/

Offline Vic1iful

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #17 on: December 05, 2010, 01:42:37 PM »
Can this be done runiing mixer aux send/return instead of amp fxloop if using a PA? Thanks

Offline hamsandwich

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #18 on: January 13, 2013, 02:02:30 PM »
I just opened up my VG-99. The pcbs are different than the 88's. Has anybody done this mod, and if so what was your process? Sorry if this has been answered before. I have done a ton of searches and couldn't find the answer. Thanks for all the help.
VG99, GR55, GR300

Offline glennfin

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #19 on: March 31, 2014, 03:23:43 PM »
I know this is an old post and I also couldn't find anyone that's done it to the 99.... so... I'm going to attempt this mod, probably this weekend... I think I can figure it out.


I just opened up my VG-99. The pcbs are different than the 88's. Has anybody done this mod, and if so what was your process? Sorry if this has been answered before. I have done a ton of searches and couldn't find the answer. Thanks for all the help.

Offline Elantric

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #20 on: March 31, 2014, 03:30:57 PM »
Take pics and post them here upon compeletion

Offline glennfin

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #21 on: March 31, 2014, 06:06:28 PM »
Yes, I certainly will....  I'm gonna figure this out.... love this kind of challange  ::)

Take pics and post them here upon compeletion

Offline glennfin

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #22 on: March 31, 2014, 07:22:31 PM »
Ok, I'm already working on this "puzzle".... I'm trying to use the switching jacks so that without anything plugged into the guitar in/out jacks, the VG99 operates normally and you don't need to jumper the in to out jacks externally as previously suggested...

Looking at the modified flow chart posted (bottom diagram), I'm assuming the switches should be shown in their "normally closed" position (no plugs inserted) The "guitar in" jack should show the switch in the up position (no jack inserted) connected to Normal pickup signal. That's the way it should be wired for use when the FX loop is not being used, but that's not the way it's shown.... To tell the truth, I'm still confused about this..... maybe it's NOT possible to have this mod where you don't need a jumper between in and out when not using th FX loop..........

Time to save it for another day....... sack time.... will attack again tomorrow.



To use the COSM Amp sims and FX with your standard Magnetic pickups - and be able to switch in and out  the hex COSM guitar patches  - all self contained , no external mixer required.

See the VG-99 Flow Chart here:
http://www.vguitarforums.com/smf/index.php?action=dlattach;topic=1485.0;attach=1612


After the VG-99 Mag PU "FX Insert" mod - you will now be able to connect your GK-3A equipped guitar to the VG-99 using the typical 13 pin cable, then when you select the "Normal Guitar" position on the GK-3A's "Guitar/ mix/ Synth" switch -  you may employ third party guitar stomp boxes on the Mag PU signal path - after the mod you will use the VG-99 "Guitar Out" jack as an FX Send - to feed the Mag P.U. signal ( which connects to the VG-99 via the the 13 pin cable) to your assortment of guitar stomp boxes (Keely Compresser, Fultone OCD,E-H Memory man, Line6 M13, etc.)  then the last stomp box the chain can now be routed back into the VG-99's 1/4" "Guitar Input" jack - - which after the modification to the internal VG-99 routing,  is now an "FX Return  for further VG-99 processing like COSM Amp sims and delays and reverbs and EQ.

To see the signal flow:

Here's the stock VG-99 Signal Flow:

(Image removed from quote.)


Here's the modified VG-99 Signal Flow after the "FX Insert" mod:

(Image removed from quote.)



Its a simple mod - move 2 internal connections ( cut & jumper) on a PC board.

The Caveat - the external FX can not be used on the hexaphonic signals ( COSM Guitar)

They only function on the standard Magnetic Pickup's signal path prior to hitting the VG-99's COSM Amp Sims.

Offline glennfin

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #23 on: April 05, 2014, 01:26:42 PM »
As I promised....

This modification converts the VG-99 Guitar "IN" and "OUT" 1/4" rear panel jacks to Send and Return Jacks.
This allows you to insert effects, tube pre-amps, distortions, etc, into the 13 pin Mag pickup signal path before
it reaches the A/D conversion section of the VG-99. The mod involves two cuts and two jumpers and can easily be returned to the
original stock configuration if needed.

Here is some information you should understand before you decide to perform this mod.

You can no longer use the "guitar out" (send) jack to feed a tuner when using the "guitar in" jack with a regular/normal guitar
plugged in there.

The "guitar out/send" jack still outputs the 13 pin mag pickup signal, when no plug is inserted into the "guitar in /return" jack.

When no plugs are inserted into the send / return jacks the VG-99 operates normally, as before the mod.


****Standard disclaimer**** Do not attempt this mod if you are not experienced with soldering, or removing or installing small
printed circuit board components.

PLEASE READ THE ENTIRE PROCEDURE BEFORE BEGINNING

1) Place the VG-99 face down on some soft material (towel) to prevent damaging the front panel.

2) Remove the 11 rear panel screws that hold the rear plate in place. (Refer to the service manual posted on this forum for more
information if needed) There are two types of screws, threaded machine screws and self tapping screws that go into plastic mounts. Make note of what screws go where when you remove them.

3) The IN/OUT board is located in the upper left hand corner of the VG-99. Carefully unplug the cable from the connector on the
back of board.

4) Carefully remove the two rear panel hex nuts holding the IN/OUT board in place. There are two black washers under these nuts.

5) ******NOTE***** BE CAREFUL when removing the board because there are 2 more washers you need to be aware of. There are 2 white insulating shoulder washers inside, located between the IN/OUT board and the rear panel. When you've removed the hex
nuts and black washers on the rear panel, carefully slide the board back from the panel keeping the jacks tilted upwards to prevent
the washers from falling down into the VG-99. (!!) Remove the washers noting the orientation of the shoulder side of the washer.
This is very important because these washers insulate the jack grounds from the rear panel preventing ground loop hum. They
must be reinstalled correctly or you will have noise problems! The only ground connection from this board to the rear panel should
be that single black ground wire (next step)

6) Unsolder the black ground wire from the solder side of the IN/OUT board making note of the location. Remove the board from
the VG-99

7) Refer to the photo below. Using a sharp exacto type knife, carefully make two cuts, close to each other (aprox 1/16") in the
circuit trace and remove the copper conductor between the cuts.

8 ) Unsolder and remove the wire jumper marked "L2". Clear the pads and holes of solder with either a desoldering tool or solder
braid.

9) Install the two insulated wire jumpers on the bottom of the board from the two "L2" pad locations to the points shown in the
photo. (red wires in photo)

10) Re-install the IN/OUT board, soldering the black ground wire back in place and making sure the shoulder washers are installed
corectly.

11) Place the black washers over the jacks on the rear panel and install and tighten the hex nuts. Re-connect the circuit board
cable connector and attach the cover plate back on the VG-99.

Note.... Do not use bare wire for the jumpers... I used insulated, 30 awg, solid, "wire wrap wire" which is our standard wire for
installing small signal jumpers on printed circuit boards at my day job. Avoid using heavy gauge wire.

Modification complete.

Here's the schematics of before and after;



Here's the top and bottom of the board pre-mod



Here's the top and bottom of the board post mod



« Last Edit: April 05, 2014, 01:32:09 PM by glennfin »

Offline Elantric

Re: VG-99 simple FX Loop for Boutique pedals off Normal Guitar PU feed.
« Reply #24 on: April 05, 2014, 02:09:44 PM »
Thanks Glennfin - Fantastic contribution to our community!
Thanks for your effort in creating this document.

I will make a PDF  and repost as a backup In the VG-99 Reference Download area

http://www.vguitarforums.com/smf/index.php?action=downloads;sa=view;down=87
« Last Edit: April 10, 2015, 05:51:05 PM by Elantric »