VG99 Patches Cycle Non-Stop...

[Steve Mac]

Greetings to everyone, I've been reading a long time but haven't had the need to post until this weekend, and thanks in advance very much for anyone with a solution to my problem.

Here is a quick description of the problem, and then I'll add some short background in case someone think it's relevant:

I was playing as I've done for years when all of a sudden the patch list on the VG99 started decreasing, one at a time, about 2 changes per second.  When it User 001 it started at Present 400 and kept heading down.  It simply started, I hadn't touched the VG99 or anything.

Now some quick background about what I did afterward, and one thing about the 13-pin cable seems quite relevant:

Unaware (until I read a thread here over the weekend  ) about not unplugging the 13-pin cable while the VG99 is on, I did just that, first from the guitar and nothing changed.  Then I unplugged the pin fro the VG99 and the cycling stopped.  I then confirmed that plugging into the unit caused the cycling whether or not the cable was attached to the guitar (eliminating the guitar's toggle switch as a cause).  I also confirmed that it did not matter which end of the 13-pin cable was plugged into the VG99 -- the cycling would start.

And here is an odd one -- this cable is the 2nd one I've owned, because I bought it a few years ago when the original cable stopped causing any sound (though I recall the tuner would work, but no sound). I was a music store and they had a cable so I just bought it instead of doing research about causes.  I mention this because I still had the old cable (figuring I'd fix it someday), plugged it in and VIOLA!  Sound again and no cycling!!  Why, I have no idea.   

All thoughts greatly appreciated.  I'm concerned the original cable will stop working again at some point and the cycling issue will return, so I'd just like to see if anyone else has seen similar behavior and has any thoughts.

Thanks very much,

Steve

[admin]

Replace the 13 pin cable

[Steve Mac]

Replace the 13 pin cable

Right, and that's part of the reason I wrote -- an old 13-pin cable that did not produce sound now does produce sound but does not cause the cycling.  Like a resurrection!     And the cycling with the problem cable occurs when the cable is plugged into the VG99 regardless whether it is also plugged into the guitar -- does that sound in any way like a VG99 problem or (like your advice suggests) just the cable, so I don't need to worry about the VG99 having an issue?

Thanks very much,

Steve

[admin]

Replace the 13 pin cable with an actual  new cable, not a worn out spare

http://btpa.com/13-Pin-Midi/

[Steve Mac]

Replace the 13 pin cable with an actual  new cable, not a worn out spare

http://btpa.com/13-Pin-Midi/

Thanks for the response, but the supposedly "worn out spare" is part of what makes this so odd.  After the more recent cable started "spinning" the presets without stopping, what could explain the newer cable causing the spinning by just plugging it into the VG99, while the cable that at one time seemed dead now works fine and does not cause the spinning?

Hmmm.

Anyway, thanks and what is the best source for a new cable (I think I bought my 2nd one at a Carvin store quite a few years ago).

Steve

[admin]

Anyway, thanks and what is the best source for a new Gk 13 pin DIN cable .

Gittler GK13 Superior Cable (WITH a right angle connector)
https://www.vguitarforums.com/smf/index.php?topic=11243.0

or

BTPA 13 pin cable
http://btpa.com/13-Pin-Midi/

[Elantric]

Read
Roland GK 13 pin Maintenance Tips.
https://www.vguitarforums.com/smf/index.php?topic=3132.0

[Steve Mac]

http://btpa.com/13-Pin-Midi/

Thanks for the source.

Steve

[Steve Mac]

Read GK13 Cable FAQ
https://www.vguitarforums.com/smf/index.php?topic=3132.0

Thanks for this -- I've bookmarked it; quite a bit of info there.

Steve

[gumbo]

Hmm...I'm not a VG-99 person (sorry!)...but it sounds like you had a temporary short-circuit in operation on some of the pins in your cable...and perhaps the VG thought you had your finger on one of the S1/S2 buttons... 

..could be something as simple as an earth (ground) wire floating about inside one of the jackplugs and touching other conductors.

The other possibility is that there might (also) be some accumulated cr@p in the actual Jack on your VG-99..  ..given that you also spoke of another unrelated intermittent fault.   (Sorry, I don't make a replacement for that one!     )

The link referred to by Elantric is important, because the action of plugging and re-plugging the jackplug into your VG after cleaning the plug will also force some cleaner into the jack itself..

HTH

Cheers,
Peter

[Elantric]

The link referred to by Elantric is important, because the action of plugging and re-plugging the jackplug into your VG after cleaning the plug will also force some clean

True, but the above technique won't cure a cable with internal  shorted adjacent pins that are making contact with ground. Pins 10 or 11 ( the GK-3 S1 & S2 contacts) are making contact with ground shield explains the constant program change when plugging in the cable in Alone -
Get the cable repaired - Or toss it away asap  if power pins 12 or 13 get shorted to ground, you might  smoke the VG-99 and discover a $400 repair bill

[Steve Mac]

True, but the above technique won't cure a cable with internal  shorted adjacent pins that are making contact with ground. Pins 10 or 11 ( the GK-3 S1 & S2 contacts) are making contact with ground shield explains the constant program change when plugging in the cable in Alone -
Get the cable repaired - Or toss it away asap  if power pins 12 or 13 get shorted to ground, you might  smoke the VG-99 and discover a $400 repair bill

Elantric:  Thank you for this, and can I ask a follow-up technical question:  Re: Pins 10 or 11 making contact with the ground shield, is that the shield within the cable itself, or a shield within the VG99?  And if I toss the old cable would I be correct you approve using the cable that is working properly to apply DeOxIt as mentioned by Peter (and thanks to Peter for his response)?

Thanks,

Steve

[admin]

There is only One Ground connection on the GK 13 pin cable - and thats the large round chrome piece that surrounds all 13 pins 

VG99 Patches Cycle Non-Stop = Pins#10 & #11 making contact with the Ground shield within the cable itself,

review more in this area
GK-13 Interface Top things to know
https://www.vguitarforums.com/smf/index.php?board=65.0

GK-13 pin Cable FAQ
https://www.vguitarforums.com/smf/index.php?topic=1293.msg6638#msg6638

Roland GK 13 pin Maintenance Tips.
https://www.vguitarforums.com/smf/index.php?topic=3132.0

====
https://www.vguitarforums.com/smf/index.php?topic=1293.msg44531#msg44531

unplugging and replugging the MIDI cable makes no difference.

Are you talking about the 13 pin cable, or a separate 5 pin MIDI cable?

These are two very separate things.

And to be correct , so we are all on  the same page,  the Roland / Boss GK 13 pin cable is NOT a MIDI cable. Roland calls the cable that goes to your GK-3  a  "GK Cable"


These GK 13 pin cables  are available in three different lengths

These cables are available in lengths of 10 feet (GKC-3), 15 feet (GKC-5) and 30 feet (GKC-10).

http://www.rolandus.com/products/productdetails.php?ProductId=91&ParentId=53


They all have 13 pins + One Ground Shield which translate to:

Pins #1-6 =  Six buffered unbalanced audio connections (one per string)
Pin #7      =  Buffered unbalanced audio connection for Normal Guitar pickups
Pin#8       =  0V to +5VDC  Control Voltage output for Synth/ COSM modeling Volume 
Pin#9       =  No Connection (except GK-3 which uses this pin as a control voltage output for GK-3's 3-way switch position.

Pin #10    =  Switch "S1" detect
Pin #11    =  Switch "S2" detect
 
Pin #12    = +7VDC power
Pin #13    = -7VDC power

The round chrome metal circular shaped part of the DIN 13 plug is the Only Ground path connection for all the above.

That's 14 connections total

Observe NONE of these connections are MIDI !!
 
For reference a block diagram of what is inside a typical 13 pin guitar preamp see below:

Roland GK-3 Circuit (NO MIDI)


I highly recommend EVERY new GR-55 owner follow the exact procedure detailed in this thread below prior to using the GR-55:
https://www.vguitarforums.com/smf/index.php?topic=3132.0

Often "new" Asian built electronics contacts, cable pins, Jacks, get coated with a very thin film of anti-corosive chemical film - to survive the boat trip on the pacific. Older gear will suffer from oxidation / corrosion just sitting in contact with the atmosphere where smog, ozone, dirt, sand, beer, sugar from spilled mixed drinks work in concert to destroy the integrity of the 14 separate electrical connections within the 13 pin cable interface.
This results in intermittent noises, crackles, Hum, string signal dropouts, weak string response, poor GTR to MIDI tracking  and a host of other anomalies.


To remove and breakdown this invisible film (new cables)  , or remove / clean the oxidation layer (old cables) from the Cable & Connector contacts, perform the following sequence  :

1 ) Apply a small amount of Caig De-Oxit to all 13pin connections on both ends of the cable. Dont forget the 13 pin connectors on your Guitar and your processor (VG-99,GR-55, etc)

2) At one end of the Roland GK13 pin cable, Depress the Cable lock on the 13pin male DIN plug end.

3) While keeping the Cable lock depressed, rapidly insert and remove the 13 pin male DIN plug end at the GR-55 / VG-99 "GK IN" jack. Rapidly do this at least 10 times.

4) Swap cable ends.

5) Repeat Step #3 above.

6) Now, while keeping the Cable lock depressed, rapidly insert and remove the 13 pin male DIN plug end at the GK-3 "GK IN" jack.  Rapidly do this at least 10 times.

7) Swap cable ends.

8 ) Repeat Step #6 above.


NOTE - DO NOT APPLY TOO MUCH CONTACT CLEANER - THAT CAN CAUSE OTHER PROBLEMS!
---
The above procedure may restore your older Roland GK 13 cables, because over a period of time, the electrical connections are exposed to air and tend to develop an oxidation layer that restricts proper electron flow.

Heres a Link to Caig DeOxit - they even sell it at your local Radio Shack now.
USE SPARINGLY
http://www.radioshack.com/product/index.jsp?productId=2104746

[gumbo]

I knew Elantric would come back with a better reply...

..only extra point I would clarify is that (under normal conditions) there should be NO connection (continuity) between the outer (ground) shell of a jackplug on a GK cable and any of the 13 pins within it.  In other words, if you have access to a multimeter or continuity tester, you can check out your own cables...   If your cables are only exhibiting this error on an intermittent basis, it points to either loose connections within one of the jackplugs, or damage somewhere along the length of the cable...

...and the 'shell' of the jackplug is attached to the screen of cable...that carries the continuity of the ground circuit through the length of the cable..   ..maintaining contact with the jackplug shell at the other end of the cable...

Accurately testing for this condition (while possibly also 'wriggling' the cables and jackplugs) can be a pain and/or impossible...obtaining a replacement cable, or even borrowing one to check for a change in symptoms is by far the easiest means for simple fault diagnosis.    I built my own simultaneous 14-way continuity tester for testing my own products during manufacture, but I wouldn't wish that task on anyone..

Bottom Line:
Read and absorb all that Elantric says..   he's the expert!   

Cheers from Oz,
Peter

[baatkarlo]

I had this problem couple years ago. Spinning patches for no reason. Turned out the copper shielding inside my Carvin SH 575 guitar cavity was earthing the 13 pin jack or had shorted something on the board with the jack in the guitar. I got it repaired as Carvin had a five year warranty on its guitars. I had spinning patches on the VG-99 with two different undamaged 13 pin Roland cables, so I knew it was either the guitar or the VG-99. Thankfully, Carvin redid the entire Ghost Hexpander MIDI circuitry for free under warranty. Its worked without problems since then.