GK2A Failing - Help

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

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billbax

Yes, a nail file will do.  From your comment, it sounds like there is a ground contact problem...obviously ::)

Going to take a look right now with a usb microscope.

Bill

pasha811

Quote from: billbax on February 06, 2022, 12:07:15 AM
Yes, a nail file will do.  From your comment, it sounds like there is a ground contact problem...obviously ::)

Going to take a look right now with a usb microscope.

Bill

In the meantime... I was able to open it and took pictures. To me it does not seem I have broken paths on the PCB.
It's a simple socket with a pin displacement that needs to be known... it's a 3pin as shown in Admin pictures. Question: Shouldn't be two? Why 3? it's a switching type right? What is the pin out schema?
Listen to my music at :  http://alonetone.com/pasha/

pasha811

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

pasha811

#28
Good News and new symptoms:

1. The Gk2A survived explorative surgery. It works fine as it should after disassembly / assembly.
2. The Socket measurements are : 14mm length (12mm 'till the PCB Edge), 7mm wide, 4.5 mm tall (a 5.5 mm will do). It should not exceed those for proper mounting
3. The solitary pin is at the front edge of the socket (the one with the hole for the jack) and there are two pins at the bottom of the package.
4. While playing hard funk the volume of the guitar goes down. If I nudge the 3.5mm cable a little it comes back to normal.

I do not think there's a cure for this but the search for a similar package begins!

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

billbax

Hi Paolo,

This will work.

1. Strip a small layer off three cotton buds. We will use one for wet polishing, one for cleaning up, and one for fine polishing.

2. Get yourself a can of liquid metal polish. In the UK we have a product called Brasso and it's very good for cleaning metal surfaces.  Forget Deoxit, as it will NOT clear tarnish.

3. Apply a moderate amount of metal polish to the 'wet' cotton bud, and wipe off excess metal polish a few times.

4. Gently insert wet bud into 3.5mm jack socket (all the way to the back of socket), and repeatedly turn a dozen or so times.

5.  Take out the wet bud and inspect.  You should have a messy looking darkened bud. Make another stripped down bud, and repeat the same process 2-3 times.

6.  Insert a 'cleaning up' bud into the socket, and turn until the excess polish is removed.

7. Insert a fresh bud for final polishing.

8. Both signal and ground sleeve contacts should now be sparkling like new.

Three trimmed down cottons buds.


3.5mm socket up close.
  All contacts can be reformed back into shape, and there shouldn't be a need for a new socket.
Btw, I see from your photo, you have a plastic enclosed socket.  No problem, all contacts can still  be reformed.

pasha811

Quote from: billbax on February 06, 2022, 03:39:54 AM
Hi Paolo,

This will work.

1. Strip a small layer off three cotton buds. We will use one for wet polishing, one for cleaning up, and one for fine polishing.

2. Get yourself a can of liquid metal polish. In the UK we have a product called Brasso and it's very good for cleaning metal surfaces.  Forget Deoxit, as it will NOT clear tarnish.

3. Apply a moderate amount of metal polish to the 'wet' cotton bud, and wipe off excess metal polish a few times.

4. Gently insert wet bud into 3.5mm jack socket (all the way to the back of socket), and repeatedly turn a dozen or so times.

5.  Take out the wet bud and inspect.  You should have a messy looking darkened bud. Make another stripped down bud, and repeat the same process 2-3 times.

6.  Insert a 'cleaning up' bud into the socket, and turn until the excess polish is removed.

7. Insert a fresh bud for final polishing.

8. Both signal and ground sleeve contacts should now be sparkling like new.

Three trimmed down cottons buds.


3.5mm socket up close.
  All contacts can be reformed back into shape, and there shouldn't be a need for a new socket.
Btw, I see from your photo, you have a plastic enclosed socket.  No problem, all contacts can still  be reformed.


Wow, thanks for your time and help!
I will have to check for the corresponding 'Brasso' in Italy.
It should be Sidol. Earbuds ok as many as I need :-)
Are you suggesting peeling off the plastic from the socket, or press upon the plastic gently to restore the 'springy' part?

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

billbax

My pleasure Paolo,

QuoteAre you suggesting peeling off the plastic from the socket, or press upon the plastic gently to restore the 'springy' part?

NO, you will NOT have to remove top of the plastic socket, as reforming the 'springy' part (signal contact), can be achieved with a stiff wire formed into a very small hook .  It works but needs some patience, good lighting and good eyesight.  Let me know when you're ready to carry this out.  In the meantime, you can go ahead do the cotton buds cleaning.

Regards,

Bill

pasha811

Quote from: billbax on February 06, 2022, 04:42:26 AM
My pleasure Paolo,

NO, you will NOT have to remove top of the plastic socket, as reforming the 'springy' part (signal contact), can be achieved with a stiff wire formed into a very small hook .  It works but needs some patience, good lighting and good eyesight.  Let me know when you're ready to carry this out.  In the meantime, you can go ahead do the cotton buds cleaning.

Regards,

Bill

Understood. Soon the store should be opened. I'll grab the metal liquid  and perform the bud trick.
Thanks!
Listen to my music at :  http://alonetone.com/pasha/

pasha811

Update :

Performed the trick!
I had to reduce the fluffy part of the earbuds a little.
The liquid was dense and creamy (I was expecting a more liquid formula) but by judging on how it worked fast on my saddles I can only imagine what was able to do inside the socket. It smelled ammonium and the safety instruction report ammonium oleate. The formula is different from Brasso but the principle is the same, even though white spirit in Brasso can perform better on some tarnish.

Done as instructed and after a test I can say that it worked.

Now the jack resists to hard funk rhythm attacks and I have also tried some sudden movement with the body of the guitar.
I have not done anything to reinstate the 'springiness' of the socket internals but as far as I can tell it worked!
Sure the connector is lousy but it feels less so. I have heard a distinct click when inserting the jack and I could feel it with the fingers on the head of the male jack.

So THANK YOU as BIG as possible! ;D
Listen to my music at :  http://alonetone.com/pasha/

billbax

Congratulation Paolo on your 3.5mm fix. 

It might be a good time to make your own hi-end normal guitar mini cable, And dump that wretched Roland cable?  A custom dual-screened cable is highly immune to EMI noise, and it will give you peace of mind in normal guitar mode.

Roland normal guitar mini cable screen (lack of).
  Makes a great antenna for EMI, and generally lowers a normal guitar input signal-noise-ratio.  To make matters worse, a GK2A/GK3 normal guitar P7 input circuit is highly susceptible to EMI noise, and a dual-screened mini cable is the only solution.


Dual-screened cable.



BINGO!  A right-angled Neutrik NP2RX might be a better choice for the 6.35mm jack, and a Neutrik AG NYS226 for 3.5mm jack.


Cheers,

Bill

https://separate-strings.co.uk

pasha811

Hey Bill,

Thanks for suggestion, I will take a look at it even if I am close to no good when it comes to soldering cables.
Strange as I can solder the Arduino Nano pins perfcetly in 30 minutes..

For the moment I have ordered a couple of those and they work.
https://www.vguitarforums.com/smf/index.php?topic=33835.0

Time to resurrect the one I made as I was afraid I made some mistakes but now I know the 3.5mm socket might have been likely the cause. ;D

Maybe I am better at soldering cables than I think lol.
Yesterday I played for 1h and all was fine, crispy and good sounding!
;)
Cheers
Paolo
Listen to my music at :  http://alonetone.com/pasha/

gumtown

The last GK-2A mini patch I made, was from cutting a simple plastic molded right angled 6.5mm pedal patch lead in half and only soldering on the 3.5mm plug.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

billbax

QuoteThe last GK-2A mini patch I made, was from cutting a simple plastic molded right angled 6.5mm pedal patch lead in half and only soldering on the 3.5mm plug.

You might be encouraging forum members to make an inferior cable.  A single braided screen is ok if you don't mind a slightly noisy antenna cable. For those who want the highest noise immunity, you must go for dual screens.

Roland GK3 braided single-screen cable VS dual-screened 10 foot cable. (High-Gain patch).
It's fair to assume a short dual-screened cable would be 4-5 dB quieter.  A spectrum analyzer doesn't tell lies. :D


gumtown

Quote from: billbax on February 08, 2022, 03:28:02 PM
You might be encouraging forum members to make an inferior cable. 

Possibly  :)

That leaves the actual GK-2A and GK-3 preamp and circuit board housing which is not shielded, maybe the weak link in the whole chain ?
If the external 'wart' or internal kit PCB was shielded in a conductive/metal case, I wonder how much more noise reduction there would be.

Something I hadn't considered before.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

philjynx

Quote from: gumtown on February 08, 2022, 04:06:37 PM
Possibly  :)

That leaves the actual GK-2A and GK-3 preamp and circuit board housing which is not shielded, maybe the weak link in the whole chain ?
If the external 'wart' or internal kit PCB was shielded in a conductive/metal case, I wonder how much more noise reduction there would be.

Something I hadn't considered before.
When I gutted my GK3 external kit and made it it internal, I wrapped the board in grounded foil. No idea if it is quieter as I have nothing to compare it with.

billbax

#40
Hi gumtown,

I think it all boils down to audio basics, with shielding or entombing an audio signal path.  My GK3 normal guitar P7 audio tests, point the finger at the short normal guitar cable.  I've plug boarded, strip boarded, and even designed a tight normal guitar input buffer PCB, and still the EMI problem remains.  A tight PCB design will remove some of the EMI, a decent single screen cable improves things again, and a dual screen cable reduces EMI further still.  It's a pity GK-2A and GK-3 are not shielded, as this would make further signal-to-noise improvements.

I shouldn't mention it, but my GK Extreme preamp is fully enclosed in a metal case.  The separate string noise-floor is around -105dB, and with carefully adjusted DAW plugins, the noise-floor drops down to about -110dB. Without question, a superior single-to-noise ratio always makes for an impressive audio experience.


billbax

#41
QuoteWhen I gutted my GK3 external kit and made it it internal, I wrapped the board in grounded foil. No idea if it is quieter as I have nothing to compare it with.
Hi philjynx,

Like it. 8)  I have visions of a laminated cooking foil enclosure, with mini PCB standoffs and discreet cable exit/entry holes. It would be quieter in comparison to an external GK3 - how much, 2-3dB maybe.  It might be possible to ground both GK2A/GK3 externally using conductive paint and a few strips of copper foil.  Just spinning ideas about before the men in white coats arrive :D

https://uk.farnell.com/electrolube/scp03b/paint-conductive-scp-silver-3g/dp/725614?mckv=suERf0kSx_dc|pcrid||plid||kword||match|e|slid||product|725614|pgrid|1349101390838609|ptaid|pla-4587918426596997|&CMP=KNC-GUK-GEN-SHOPPING-SMEC-WHOOPS-Test725-maxCPA-Step1&gross_price=true&msclkid=e5b48e4d49d1192045d0ec4e52da33a0

pasha811

I think the men in white will arrive late, after the mods were done! ;D
Impressive food for thoughts gentlemen!
Crossing fingers the ammonia washing of my GK2A will last. Yesterday got another long playing session and it went with only a glitch, as my whammy bar was touching the cable. That produced a panic moment. It looks like the adjustment of the springy parts in the socket is necessary even if reinserting the cable with a fast out/in action made me ending my recording session with no other glitches.
Joni Mitchell once wrote in a song... 'Short sighted Businessman, nothing last for long'..


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

billbax

#43
Hi Paolo,

I feel reluctant to add another post.  :-[

1. If you have a multimeter with an audible continuity checker, you can wiggle check your mini cable.

2.  Did you check the PCB for tiny track breaks, as sockets tracks often break? You may need X5 magnification for this check.

Please don't assume the problem is a 'tip' contact issue, as the simplest of fixes might be a ground sleeve pressure contact -  remember the sewing needle comment on my first graphic.  Please post a close up photo of the socket entry under good lighting.

Bill

pasha811

Quote from: billbax on February 09, 2022, 03:00:46 AM
Hi Paolo,

I feel reluctant to add another post.  :-[

1. If you have a multimeter with an audible continuity checker, you can wiggle check your mini cable.

2.  Did you check the PCB for tiny track breaks, as sockets tracks often break? You may need X5 magnification for this check.

Please don't assume the problem is a 'tip' contact issue, as the simplest of fixes might be a ground sleeve pressure contact -  remember the sewing needle comment on my first graphic.  Please post a close up photo of the socket entry under good lighting.

Bill

Do not feel that. Every bit of info and help is greately appreciated.
I Checked with a x3 and found nothing...
I will try to produce a picture of the socket in the next days.

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

philjynx

Quote from: billbax on February 08, 2022, 05:44:07 PM
Hi philjynx,

Just spinning ideas about before the men in white coats arrive :D
.....
You may have a long wait for them, they're showing no signs of leaving me yet.

pasha811

Resurrecting this thread as the problem is now back.

I can reprogram the same procedure with polish cread and buds but my eyesight is not at the point I can be of same use doing the needle trick to restore the springiness inside the socket. (I was not able to obtain a viable picture). A USB microscope needs to be bought and in any case I do not know if I can fix it. So I am left with those options:

1. Forget about fixing it : using a normal cable to connect to Guitar IN. This brings two cables and some annoyance but I play and record at home with this guitar. If I ever do a live show again I will use my other GK3 guitar which works fine

2. Looking for a used GK2A on found for 100 used. It seems to me too much, being a GK3 new selling for 169 Euros

3. Unsolder the case, solder three wires and mod the GK2A with an 'external dongle' this time a 6.3mm female jack attached to a cable coming out from the GK2A I'd use a shielded dual pole as suggested. Ugly as it seems ... it might work if I can have access to GK2A schematics. Unsolder and solder can be done but what worries me the most is where I should solder the cable coming out  to the female jack.

4. Get a new GK3 (actually I have a spare one that should have been mounted to my third guitar by now but I have stopped the project) , butcher the pickguard (a new one as the older is 30 years old and original - now with holes for the GK2A)

So those are the options. What would you do? Keep in mind I am not a super wizard with DIY stuff. I can make holes  :) destroy with an hammer  ;) and with a lot of patience use my Dremel for carving (not easy).  I can measure, do the setup to my guitar and clean the frets and fret-board  8)

Let me know!
Thanks
Paolo
Listen to my music at :  http://alonetone.com/pasha/