Can I connect Ibanez 1520GK Piezo pickups to a new GK3 internal board?

Started by peter_dawson, September 13, 2021, 07:44:47 AM

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peter_dawson

Hi Folks.
I have an Ibanez RG1520GK which has LR Baggs Piezo pickups under a floyd rose tremelo. I love this guitar and don't want to change the piezos or the bridge. However, the internal circuitboard that came with the guitar is damaged and needs replacement. I believe that the original circuitboard is a modified GK2A board although not 100% sure.

I am contemplating replacing the damaged original circuitboard with a new GK3 internal circuitboard. I note that the plug in the 1520 is a different size and has different wiring colours compared to the GK3 plug and wires but I am thinking I can adapt the original Baggs/1520 wiring to fit onto the new GK3 board by splicing one onto the other.

I'm not sure if this will work in practice e.g. the old board might be non-standard in some way that accommodates the original Baggs piezos. Do any of you guys know if this will work?

Any help appreciated

p

admin

Post pics

And try to get close up picks of top side of bad PC Board



Here is your internal board, has two PCB mounted Switches , so its unique to that guitar.

A few others here own same guitar

The internal bad board is an early Internal Roland KIT board, GK-2A type, the LR Baggs piezos have different characteristics than RMC or Graphtech.

Many report the stock GK Kit Preamp board also works in that guitar, but close up pics of tip of your board will help determine if the input impedance has been modified for this Ibanez model

The repair path is order a new GK-KIT-GT3 from Andersons UK , and use that as basis for replacement, after carefully documenting the current GK internal Electronics with photos.

Goal is determine the input impedance change on your PC board vs the GK-KIT-GT3

It will take some time



A member owns RG1520GK here
https://www.vguitarforums.com/smf/index.php?topic=28735.msg209113#msg209113

peter_dawson

Many thanks for the reply. That's very helpful. I have some pics of the board below - can you see if the board has been modded from those snaps? would a swap out with a new GK3 board work do you think?



admin






admin


Need top down view of this board with all resistors
No need for bottom views

But so far it appears this Ibanez preamp has 860k and 560K input impedance - suitable for piezo saddles, and contrary to rumor
- its not identical to a GK-3 preamp!

A working GK-3 preamp could be adapted, but locating a technician with skills to swap 0805 resistors in UK may be a hurdle - possible the local Robot club, RC Hobby Club, Makerfaire  UK (Maker Faire UK Newcastle upon Tyne, UK) could perform the soldering mods.

IMHO a capable repair technician should be able to repair the existing board - as bulk of the board is same as a  GK-2A

See Schematics PDF attachments here
https://www.vguitarforums.com/smf/index.php?topic=73.0

gumbo

...hmm...

maybe try to find a (GK2-A equivalent) board out of a Roland-Ready Strat as a starter and work from that...  ??

Just a mad morning thought...   ;)

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

peter_dawson

Wow. That is a very specialist piece of hardware. Sounds like the straight swap of the old board for a new GK3 isn't going to fly?

If so, I think I might get the soldering iron out myself as the damage is just the wires becoming detached from the board rather than a fundamental fault in the board itself. Maybe if I'm _really_ careful I can resolder it

peter_dawson

Hi @admin.
Apologies for the delay. Here is that top-down view of the board with resistors - what do you think?

admin

Quote from: peter_dawson on September 28, 2021, 12:07:25 PM
Hi @admin.
Apologies for the delay. Here is that top-down view of the board with resistors - what do you think?

It's this schematic -GK-2A

But with different 560k ohm  piezo input impedance for the 6 Piezo channels

peter_dawson

OK. So if I swapped that board for a new internal GK3 and wired the old RG1520 Stock piezos across to that new GK3 board, would it work?

admin

Quote from: peter_dawson on October 05, 2021, 11:03:31 AM
OK. So if I swapped that board for a new internal GK3 and wired the old RG1520 Stock piezos across to that new GK3 board, would it work?

Not well, must clone the 560k ohm input impedance employed  old Ibanez board for each piezo input preamp (6) = 12 resistors to swap on Roland board

peter_dawson

Aha. Many thanks. I think that decides it : I will resolder the wires onto the old board and find some way to connect a new 13pin plug to replace the one I bust. The board works but several wires have been ripped off and the old 13 pin plug is bust so that needs replaced. Better to stick with the devil I know in this case I think.

Thanks for the most expert assistance. I will post back how I get on.

Do you know how I can get suitable replacement for the 13 pin plug and the mini board that goes with it?

admin

Quote from: peter_dawson on October 05, 2021, 12:55:00 PM
Aha. Many thanks. I think that decides it : I will resolder the wires onto the old board and find some way to connect a new 13pin plug to replace the one I bust. The board works but several wires have been ripped off and the old 13 pin plug is bust so that needs replaced. Better to stick with the devil I know in this case I think.

Thanks for the most expert assistance. I will post back how I get on.

Do you know how I can get suitable replacement for the 13 pin plug and the mini board that goes with it?

The original is a Roland Unit from the older Kit, they moved a few wires making latest version incompatible

peter_dawson

Not a problem. If I buy cable with a female 13 pin socket on the end then I can seat the female socket facing out through the hole in the body and then strip the cable to get at the wires and connect them back to the main board and don't think I will need the mini board at all.

Do you have a diagram of how to connect up that main board e.g. what wires got to the volume pot;what wires are what connecting to the 13 pin DIN?

admin

The schematic is posted here, verify connections with multimeter .

Not all sub ribbon header connector to GK13 output jack are depicted in schematic,  but it does accurately depict where all the electrons go. After final assembly ;)


It's this schematic -GK-2A

I always advise take internal circuit photos of working gear,  as it often serves as only reference when trying to fix dead units which have missing wires.




gumbo

I can possibly help you with a 13-pin jack with attached tales... ;)

Refer:  https://www.vguitarforums.com/smf/index.php?board=181.0


PM me for more info.

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

admin

Quote from: gumbo on October 06, 2021, 02:09:03 PM
I can possibly help you with a 13-pin jack with attached tales... ;)

Refer:  https://www.vguitarforums.com/smf/index.php?board=181.0


PM me for more info.

Regards,
Peter

But Synthlynx 13 pin  jack may require mods to your Ibanez body ( routed for a 13 pin jack from a Roland GK internal kit)  to fit its compact dimensions

https://ibanez.fandom.com/wiki/RG1520GK

gumbo

If the original (Roland) jack mounting plate as shown is still in existence on the guitar (or can be repaired), a Synth-Linx Jack will bolt directly to the back of that plate as the Synth-Linx Jack shares the same exact (2) mounting points as the Roland jack...    ....the replacement Synth-Linx Jacks that I produce for the Roland-Ready Strat and the GC-1 Strat are installed in precisely that manner.

No change to the routing is necessary, and the original mounting plate still covers the MBH (Mighty Big Hole) that was required to accomodate the Roland jack in the first place.   ;)

HTH

Peter



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

Christophersad

hello guys,sorry for resumiong an old post but ill try,i have a 1520gk too and im wondering :

whats that black mini  switch on the ibanez/gk board for?

can the magnetic pickup travel trough the 13 pin in this model?

ty
Chris