GK2A Failing - Help

Started by pasha811, January 31, 2022, 04:01:21 AM

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pasha811

Recently I have observed problems in GK2A connection with Normal Guitar Output.
Sometimes I have to touch gently the mini mono jack input plug to listen to my guitar output.
As my other posts show, I have done the following:

Solder a Jack to mini jack cable
Clean the Mini Jack female socket on the GK2A with contact cleaner
Bought 2 cables on Amazon that came presoldered and working
Tester shows that the cable itself it's not a problem, as it's not failing continuity tests

At this point it might be the mini jack (3.5mm) mono female of the GK2A having some jerky behaviour. 
So... can it be replaced? Have you ever had such problems?

Thanks a lot
Paolo
Listen to my music at :  http://alonetone.com/pasha/

gumbo

If you hold (or tape) the 3.5mm jackplug to one side while it is inserted in the jack, does the problem persist?

If not, start thinking about the accuracy of the diameter of the jackplug's sleeve, and whether it is sufficient to remain in constant (!) contact with the outer part of the 3.5mm jack itself.

Not the first time I've come across glaring irregularities (of measurement) in cheap jackplugs...

Just saying...

HTH

Peter
Read slower!!!   ....I'm typing as fast as I can...

Harry1227

Hi. I have the same problem with my GK2A. Temporarily I solved it by bending the contacts with a needle. In my case, the pickup was very old and had survived more than one intervention by the previous owner. The contact cleaner is useless when the socket is physically loose or has cracks in the housing.
While I'm collecting 3.5-inch mono sockets from old tape recorders and other outdated equipment. When I get tired of bending the contacts, I will peel off the gk2a from the guitar and replace the socket.

philjynx

My guess would be that the spring connector in the socket that sends the signal to the tip of the plug is either worn, dirty or has bent out of shape and doesn't make contact properly. You should just be able to feel it riding over the ridge of the tip of the plug as you insert the plug if there's no 'lumpiness' to the insertion at all then I'd go for the bent out of shape option. Try doxit or a similar contact cleaner, use the plug as your cleaning implement unless you have something you can insert to clean it without introducing fluff (could be there's already fluff there causing the problem).

billbax

Agree philjynx, it probably is the spring connector contact.  I'm thinking both surfaces are making  good contact, but tarnish may have set in.  An abrasive 3.5mm plug will clear any tarnish buildup on socket sleeve and tip contacts.

Possible solution:  Roughen up an old 3.5mm jack with a medium grit emery paper, insert into 3.5mm socket and turn the plug 4-5 times.

Here's something that definitely works for old 13-pin sockets, and the same goes for most sockets.


admin

#5

pasha811

 ;D
Guys you are all great. I will try each suggestion then Harry's as last one.
I like the carburator thing... that's crazy! ;-)
Does someone have done the 3.5mm jack replacement in the past? Can you post a picture?

Thanks a lot!
Listen to my music at :  http://alonetone.com/pasha/

admin

Quote from: pasha811 on January 31, 2022, 08:50:11 AM
;D
Guys you are all great. I will try each suggestion then Harry's as last one.
I like the carburator thing... that's crazy! ;-)
Does someone have done the 3.5mm jack replacement in the past? Can you post a picture?

Thanks a lot!

These are common 3.5mm  right angle PCB mount jack on GK-2A

pasha811

Quote from: admin on January 31, 2022, 09:15:17 AM
These are common 3.5mm  right angle PCB mount jack on GK-2A


Great! Is the pin displacement standard? It seems like doable. The little spring is a Roland thing or happens on all 3.5mm female jacks of this kind?
I have tried and no spring seems there..that's why I need to tap it up here and there to make it work.

Thanks a lot
Paolo
Listen to my music at :  http://alonetone.com/pasha/

philjynx

Quote from: pasha811 on January 31, 2022, 10:51:04 AM
....The little spring is a Roland thing or happens on all 3.5mm female jacks of this kind?
....
All physical things wear out.
ALL jack sockets 3.5 or 6mm have sprung contacts.
Not a Roland thing. Just a wear thing.

pasha811

Quote from: philjynx on January 31, 2022, 11:37:00 AM
All physical things wear out.
ALL jack sockets 3.5 or 6mm have sprung contacts.
Not a Roland thing. Just a wear thing.

My bad. I took this in 2011, used and kept the little cable hooked until 3 weeks ago when it failed..good resistance anyway.
Listen to my music at :  http://alonetone.com/pasha/

gumtown

Quote from: philjynx on January 31, 2022, 11:37:00 AM
All physical things wear out.
ALL jack sockets 3.5 or 6mm have sprung contacts.
Not a Roland thing. Just a wear thing.

Same goes for us too !!  :P
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

philjynx



pasha811

Listen to my music at :  http://alonetone.com/pasha/

pasha811

A quick visit to the nearby physical stores result in only stereo female jacks.
Next step I will disassemble my GK2A unit to have a closer look at the PCB mounted female Jack. I will took note of the pin layout and measure the dimensions, then I will make good use of the list admin posted. Although it could work by using a normal cable together with GK I really would like to restore it to its full glory.

Thanks so far,
Paolo
Listen to my music at :  http://alonetone.com/pasha/

admin

#16
Stereo jack are Fine

Just wire the Ring contact as an addition Audio Ground

I suspect the genuine 3.5mm TS jack is a switching type. That grounds the Tip anytime its not occupied

Impossible to find btw

pasha811

Quote from: admin on February 01, 2022, 02:44:51 PM
Stereo jack are Fine

Just wire the Ring contact as an addition Audio Ground

I suspect the genuine 3.5mm TS jack is a switching type. That grounds the Tip anytime its not occupied

Impossible to find btw

Thanks Admin. The stereo jack type I have found so far are the flat house style. Larger than taller. The one I need is the taller than larger as a multi storey building.
Good to know I can adapt one of the correct size but what happens if it's not switching?
Will it jeopardize the whole pickup? More noise? In that case is still worth the repair?

Thanks
Paolo

Listen to my music at :  http://alonetone.com/pasha/

admin

Quote from: pasha811 on February 01, 2022, 10:15:06 PM
Thanks Admin. The stereo jack type I have found so far are the flat house style. Larger than taller. The one I need is the taller than larger as a multi storey building.
Good to know I can adapt one of the correct size but what happens if it's not switching?
Will it jeopardize the whole pickup? More noise? In that case is still worth the repair?

Thanks
Paolo

always connect the Normal pickup and you will be fine and lowest noise  - as strings are grounded via this connection

pasha811

Quote from: admin on February 01, 2022, 10:52:21 PM
always connect the Normal pickup and you will be fine and lowest noise  - as strings are grounded via this connection

... And that incudes bypassing the little guitar to GK2A Cable and using a normal guitar cable from guitar to VG99 GTR IN right?

Thanks
Paolo
Listen to my music at :  http://alonetone.com/pasha/

admin

Quote from: pasha811 on February 02, 2022, 12:37:23 AM
... And that incudes bypassing the little guitar to GK2A Cable and using a normal guitar cable from guitar to VG99 GTR IN right?

Thanks
Paolo

Too complex to predict noise outcome output in that scenario 80% running 2 cables live for 3 sets at live gig typically results in singer tripping over your spaghetti stage mess

pasha811

I will be at home and the only stumbling on my cables lol.
... However this will fuel wife having fun of me .. ;D
Listen to my music at :  http://alonetone.com/pasha/

pasha811

Quote from: billbax on January 31, 2022, 07:36:11 AM
Agree philjynx, it probably is the spring connector contact.  I'm thinking both surfaces are making  good contact, but tarnish may have set in.  An abrasive 3.5mm plug will clear any tarnish buildup on socket sleeve and tip contacts.

Possible solution:  Roughen up an old 3.5mm jack with a medium grit emery paper, insert into 3.5mm socket and turn the plug 4-5 times.

Here's something that definitely works for old 13-pin sockets, and the same goes for most sockets.



Done as suggested. Added some more deox. It seems better and that pushes me to try again but the spring is not 'catchy' and the 3.5mm needs to be pushed inside with little nudges from time to time. The GK2A works fine as an hex PU. Thanks so far I will keep you posted. 
Listen to my music at :  http://alonetone.com/pasha/

billbax

Good to hear things are a little better Paolo.

With the abrasive 3.5mm jack, use a medium-heavy emery paper to roughen up the jack, and make sure the score lines are vertical this time.  Horizontal lines (jack circumference) will have some affect, but vertical lines will have an instant affect.  Roughening up the jack tip will be difficult, and suggest the use of a small file with horizontal lines.

You mentioned the socket works better with added pressure to the 3.5mm jack plug.  Have you checked the sockets PCB track pads for breaks? This might sound iffy, but you could try passing a soldering iron over the sockets track pads. A solder pad reflow can't do any harm.  If none of this works, I'll check my GK2A 3.5mm socket internally with a USB microscope - there is a more radical fix btw.

Bill

pasha811

Quote from: billbax on February 05, 2022, 02:18:28 PM
Good to hear things are a little better Paolo.

With the abrasive 3.5mm jack, use a medium-heavy emery paper to roughen up the jack, and make sure the score lines are vertical this time.  Horizontal lines (jack circumference) will have some affect, but vertical lines will have an instant affect.  Roughening up the jack tip will be difficult, and suggest the use of a small file with horizontal lines.

You mentioned the socket works better with added pressure to the 3.5mm jack plug.  Have you checked the sockets PCB track pads for breaks? This might sound iffy, but you could try passing a soldering iron over the sockets track pads. A solder pad reflow can't do any harm.  If none of this works, I'll check my GK2A 3.5mm socket internally with a USB microscope - there is a more radical fix btw.

Bill

Is a nail file ok? Otherwise I have to buy one.
I will open the GK2A to check for tracks on the PCB. It will be a good time to measure the 3.5mm socket and take pictures.  Although admin says that they are impossible to find and possibly a switching type it's worth a try.  What also happens is that all of a sudden in some patches on GP10 with modeled synth and guitar I got the mother of all buzz.. if I remove the little cable it goes away. It's the typical sound of unearthed ground path. If I reinsert the little cable in place it goes away but only in a certain position. Nudge fwd (push gently to enter the socket) and up by putting a finger between the guitar and the little cable socket. Today I will try a couple more cables I got but something tells me the socket is gone..,

Thanks for help
Paolo
Listen to my music at :  http://alonetone.com/pasha/