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Alex Lifeson Les Paul - Wiring issue

thauma

New member
Joined
Oct 13, 2015
Messages
6
Hi,

I have an Alex Lifeson Les Paul with the graphtech piezo bridge.

I've had some intermittent issues with the bridge, but to cut a long story short, some of the wires from the bridge have broken / snapped at the piezo (I think a bridge adjustment caused the issue). However I have sourced the relevant parts and was just about to fit them when I noticed that there is a suspicious looking BLUE wire that I believe is disconnected from the on/off/volume pot for the piezo. The other end of the wire is connected to the QSW connection point on the acousti-phonic pre-amp.

Does anyone have a wiring diagram for this guitar, or if anyone owns one could you take a picture for me?

I'm not electronic-savvy, so if it's not a simple fix for me then I'll get a tech to look at it........ but I don't want to confuse them with this non-simple wiring, so if I can go with schematic/diagram/pictures that should make things easier

Thanks in advance.

Cheers

Dave#...
 

thauma

New member
Joined
Oct 13, 2015
Messages
6
I have no first hand experience of them but there are some wiring diagrams and info here https://graphtech.com/pages/ghost-wiring-diagrams

QSW seems to stand for quick switch so your assumption that the blue wire goes to the on / off switch would appear to be correct, this diagram shows a blue wire from a push pull pot switch https://cdn.shopify.com/s/files/1/2372/8913/files/push-pull-as-a-quickswitch_1.pdf


Thanks Paul, that's very helpful.

Indeed I have the Graphtech diagrams, and have also received a wiring diagram from Gibson (and another forum). However to my (simple) mind there seems to be a contradiction in the diagrams .... assuming that I am reading them right.

The contradiction appears to be that the Gibson diagram seems to have the blue wire - OPEN..... and that is causing me some confusion as graph tech indicate that it goes to the switch.

Following the Graphtech diagrams, which are pretty good to be fair, I need to know where to connect the wire when looking at a gibson specific push/pull volume pot.

I am making progress, but not being a wiz with electronics, I want to be careful so that I don't screw anything up.

If anyone has any (relevant) thoughts, advice, guidance or photo's of the volume / tone pot cavity that would be most welcome.

Cheers

Dave#...
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
673
If you can post the diagrams and ideally a photo of the guitar wiring showing the switch I might be able to help more.
 

thauma

New member
Joined
Oct 13, 2015
Messages
6
Paul,

You previously passed through the link to the graphtech site with the manuals and wiring, but here is a summary of the pages I was referring to https://www.dropbox.com/s/7raagn49vhgn9np/Screenshot 2020-03-28 12.53.30.png?dl=0

This is the diagram I was sent by Gibson https://www.dropbox.com/s/7rvhq5giwoay5k2/Alex Lifeson Schematic.pdf?dl=0

and here are some pictures of the guitar wiring (apologies for the quality)


Note that the BLUE wire in the pictures is shown on the Gibson wiring diagram as RED/BLUE(OPEN)

Ultimately, I don't know if the loose blue wire should be connected to anything. It appears from the Gibson wiring that it shouldn't, but it is strange that they have routed it through to the control cavity, rather than simply clipping it short.

So I don't know if you can make sense of the pictures / diagrams. If you can't - I thank you for your help so far ... the internet can be a great place, and is full of knowledgeable people such as yourself.

Cheers

Dave#...
 

thauma

New member
Joined
Oct 13, 2015
Messages
6
If you can post the diagrams and ideally a photo of the guitar wiring showing the switch I might be able to help more.


Paul - I have posted a reply (yesterday) with links to diagrams and pics.... but the post is awaiting approval from an admin..... hopefully it will appear soon
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
673
Yes, it certainly looks from the Gibson schematic that it's not connected but strange that it would be left like that with a bare end, at the very least I would expect it to be insulated in some way. I would think the thing to do is try it with the wire disconnected first, if everything works as it should then just tape it up and leave it, if it doesn't work properly then I would try it connected to the switch terminal above the red and black wires. At the end of the day it's all signal path wiring so it's not going to cause any harm if it's not connected correctly, it just won't work as expected!
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
673
Just thinking a bit more about this, the Graphtech diagram shows the red black and blue wires going to a 3 position switch to select either the normal pickups, the piezo or both together. I guess the Gibson switch is only a 2 position push/pull switch so only 2 of these options would be available? That would reinforce the idea that it should not connect to anything.
 

thauma

New member
Joined
Oct 13, 2015
Messages
6
Paul,

your input is greatly appreciated, and as a non expert in the field of wiring/electronics it gave me some confidence that the wire shouldn't be connected and is actually a 'red-herring'; more importantly it also gave a direction to fault find if more investigation had been required.

I've replaced the graph tech saddles in the bridge, and routed everything appropriately, and then connected it all together. All components of the guitar are now working as they did prior to the original issue.... and the spurious blue wire (RED/RBLUE (OPEN) on the gibson diagram) is not needed, so I have tidied that away.

I suppose that the wire should have been clipped in the factory ... but never mind. My problem is solved, my guitar is fully usable again and my concerns were alleviated by your input.

Many Thanks

Cheers

Dave#...
 
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