Help on a complex wiring plan -Gib LP Professional

[pemorin]

Hello,

I have a Les Paul Professional that I am trying to bring back to shape, but I am not really familiar with electronics. I have found plans and schematics of Les Paul Recordings here in the past (similar model), and thought I should try my luck for some help.

So I got my hands on a official Gibson schematic for my model, but when i got to work on the real thing, it was a little bit more complex.

Armed with the plan, a picture of another professional and one of a personal, my friend and me drew a plan of every wire and connections needed.

If someone with experience in this could help me by confirming that we got the "translation" correct, I would be eternally gratefull.

Here are the pictures :









Thank you !

[sbgodofmetal]

Hello and welcome to GN2!!!

This is a very interesting setup, to clear a few things up how many position do the rotary and blade switch have??? And what style switch are you using for the phase??? Are those 'diodes' l see on that volume pot??? whats their purpose there??? ls this dual humbuckers or p-90's???

Reguardless thats a hellova setup.

+1 for posting the schematics and gutshots they've inspired the lil' hamster in my head. ;D

[newey]

pemorin-

Hello and Welcome to G-Nutz2!

I like that you have offered your own attempt at translating the schematic into a wiring diagram. (It's a lot better than just expecting some kind soul to do it all for you!)

But, your diagram needs work:

1) your phase switch, as shown on the schematic, requires one output to ground and the other to the bridge side of the 3-way pickup selector. Yours has one wire going to the decade switch, and no ground is shown.

2) The neck pickup's connections to the three-way switch are unclear, as is that switch in general; I can't tell which connections are which, and I suspect you are showing a frame ground in there which is confusing things. In any event, the neck pickup's wiring to the three-way may or may not be right, I can't tell from the diagram.

3) The common connection (the center one) off the three-way switch goes to lug #5 on the decade switch, and from there to the CW lug of the bass tone pot, and from there to the tone switch lug #7. I don't see that on your diagram.

There may be more; I stopped at three . . .

For your reference, there are several things to note about Gibson's drawing. First, where 2 wires cross but do not connect, the one wire "humps over" the other one. If there's no "hump", it's a connection.

Second, the diagram for the three-way is a little tricky, as the schematic shows a sort-of "see-thru" approach, showing how the two sides are joined in the center position. The two center levers (with the triangles) shown contacting the A and B sides join together to form a single center terminal. The two sides thus represent the A and B connections.

The pot connections seem to be giving you trouble as well. Look at the schematic for the treble pot (labelled as "Treble 1K L"). The "hot" end of the pot (i.e., the Clockwise connection) is wired to Lug #3 on the tone switch, the counterclockwise lug is not wired to anything, and the center lug (the "wiper", shown as an arrow) is connected to ground through a 33KΩ resistor in series with a 2.2µf capacitor.

HTH

[pemorin]

Thanks for the reply !

Jun 3, 2011 17:19:11 GMT -5 sbgodofmetal said:

How many position do the rotary and blade switch have???

Well the decade switch (rotary) is a strange thing, I'll try doing a different reply about it.
For the Tone selector (blade switch), there is 3 positions, labeled as 1 2 3 on the outside of the guitar.

Jun 3, 2011 17:19:11 GMT -5 sbgodofmetal said:

What style switch are you using for the phase???

Its an On Off type of thing :

Jun 3, 2011 17:19:11 GMT -5 sbgodofmetal said:

Are those 'diodes' l see on that volume pot??? whats their purpose there???

It must be my lack of drawing skill that confuse you
Theres just a pot, some resistance and a cap.

Jun 3, 2011 17:19:11 GMT -5 sbgodofmetal said:

ls this dual humbuckers or p-90's???

It's actually dual low impedance pickups. My guitar is a strange one, straight out of Les Paul's twisted brain ;D

[sbgodofmetal]

Oh ok they're resistors, l was looking at the gut shot on that one. l've been cleaning all day and l think the cleaner fumes got to me cause normally i'd of known that one.

[pemorin]

Thanks for you help

You reply is very technical for me so I'll take it slow, one by one

Jun 3, 2011 17:59:51 GMT -5 newey said:

1) your phase switch, as shown on the schematic, requires one output to ground and the other to the bridge side of the 3-way pickup selector. Yours has one wire going to the decade switch, and no ground is shown.

I remember from looking at other pictures that the phase switch on the schematic is different then the way it's hooked up in a real guitar. From the photos, i could see the red wire coming out from the lower left lug to the "patch bay" lug #5. From that same lug, another red wire goes back up to the pickup selector. Does that work, or is there an issue with it connecting on the patch bay ?



For the ground, the lug #2 acts as one(same for #7), at least I think so, as seen in this photo :



Close up of my phase switch (most of the wiring in my guitar is not ok at the moment but this part looks ok compared to other pictures I've seen, minus the 2 wires coming from the pickup, for obvious reasons) :


Let me know if it's ok.

[pemorin]

Jun 3, 2011 17:59:51 GMT -5 newey said:

2) The neck pickup's connections to the three-way switch are unclear, as is that switch in general; I can't tell which connections are which, and I suspect you are showing a frame ground in there which is confusing things. In any event, the neck pickup's wiring to the three-way may or may not be right, I can't tell from the diagram.

Yeah, I did put a frame ground, but only as a reminder that that would be grounded. It gets grounded back down at lug #2 of the patch bay. You are right, it looks like it gets grounded right up there, but it is not. My fault.

Lets try this reenactment instead :



Let me know if I got it wrong, thanks

[pemorin]

Jun 3, 2011 17:59:51 GMT -5 newey said:

3) The common connection (the center one) off the three-way switch goes to lug #5 on the decade switch, and from there to the CW lug of the bass tone pot, and from there to the tone switch lug #7. I don't see that on your diagram.

That also was an "adjustement" I did because of real life photos from other guitar, as seen here :



Can it affect the sound if it goes to the tone switch log #7 first as in the pictures ? I still have difficulties sometimes picturing the relation between the plan and the effect on the sound it will produce.

Thanks a lot for your help

[pemorin]

Jun 3, 2011 17:59:51 GMT -5 newey said:

The pot connections seem to be giving you trouble as well. Look at the schematic for the treble pot (labelled as "Treble 1K L"). The "hot" end of the pot (i.e., the Clockwise connection) is wired to Lug #3 on the tone switch, the counterclockwise lug is not wired to anything, and the center lug (the "wiper", shown as an arrow) is connected to ground through a 33KΩ resistor in series with a 2.2µf capacitor.

HTH

Ok, not sure i got it all, but I think I did. So if I apply what you said to my plan, the thing that would be incorrect is which lug receives the brown wire, right ?
For the ground, does the top of the pot work ? That is what I tried to picture.

Thanks

[pemorin]

Jun 3, 2011 17:59:51 GMT -5 newey said:

For your reference, there are several things to note about Gibson's drawing. First, where 2 wires cross but do not connect, the one wire "humps over" the other one. If there's no "hump", it's a connection.

Yes, my friend tried to explain that to me. I know there are still a couple times on my plan i forgot to hump over

Jun 3, 2011 17:59:51 GMT -5 newey said:

Second, the diagram for the three-way is a little tricky, as the schematic shows a sort-of "see-thru" approach, showing how the two sides are joined in the center position. The two center levers (with the triangles) shown contacting the A and B sides join together to form a single center terminal. The two sides thus represent the A and B connections.

Yeah i did mine pictured from the top. Similar to the picture i posted as the reenactment. I'll see if I got it worng depending what you say about that one.


Well I think i covered it all. Time to go eat. Thanks for you help guys.

[pemorin]

Here is a little explanation on the strange circuitry.

Taken from jbwid.com/guitar/lpp02.htm

[newey]

pemorin-

I was simply comparing the Gibby schematic to your diagram; I did not attempt to compare the wiring in the pictures to either your drawing or theirs.

Whether the wiring in either your guitar and/or the other one you photographed matches up to the schematic or not is an open question. First, there may have been alternate versions of the guitar from Gibson. Second, the schematic can be translated in several different ways to an actual wiring plan or diagram; the wiring in the guitar may be "equivalent" to, but not exactly equal to, the schematic. Finally, someone may have screwed with it before you got it.

Since I gather from your post that it wasn't working when you got it, and was in fact missing some parts, option #3 is looking good . . .

I can't tell much of anything from your pictures. They're good photos, but there's enough going on that it's hard to trace anything out. And your disambiguation of the switch still has me puzzled as to which wires are connected where.

But there are a few basics we can look at here.

First, Gibson's schematic will do what it it supposed to do, and if that comports with what you want it to do, then wiring it according to the schematic is your best bet.

The basic scheme here is the that the bridge pickup goes first to the phase switch, and then from the phase switch to the 3-way switch. The neck pickup goes directly to the 3-way. The bridge pup hot lead attaches to the bridge side of the 3-way; the neck hot to the neck side. Both pickup grounds go to any convenient grounding point (back of a pot is fine).

The center terminal of the 3-way then goes "out" to the rest of the switching and controls. Think in terms of the signal flow so far- each pickup goes to the three-way switch, with the bridge pup being selected for phase (or not) first.

At the three-way switch, a pickup or pickups are selected, and the signal travels on to the "tone network". This network comprises several elements- a bass pot, a treble pot, a "decade switch" and a "tone switch".

Think of it as if it were one big tone control, albeit a complicated one. But the whole shebang could be easily replaced with a single tone pot- simpler but with less variability. The whole "tone network", as I'm calling it, is a module, a discreet piece of the larger design.

After the signal gets bent up some in the tone network, it goes on to the volume pot and then out to the jack.

I hope that wordy description actually helps make it easier to see what's happening here.

Can it affect the sound if it goes to the tone switch log #7 first as in the pictures ?

Not sure on that, let me study the pix some more.

[pemorin]

That wordy description was great. And I was happy to be able to do mental check marks as I read it.
My drawing may be hard to read since it's probably full of errors and faults (like forgetting to hump over a wire), but reading your flow and reading the tone selector information has helped me to get a better grasp... and I am starting to think the plan is ok.

I will try to do a little thing to make sure.

[pemorin]

Ok,

This is the way i see it, let me know if you find a fault.

The tone switch lugs are numbered 1 to 4 on the top row left to right, and 5 to 8 on the bottom row, left to right.

1 and 8 are always active in the flow.

When tone 1 is selected, lugs 2 and 5 are active.
Compared to what jbwid.com says, the way i see it, the decade is bypassed in Tone 1 mode.
So its straight Pickups to 150 resistance and 0.47 cap, then volume then out.


When tone 2 is selected, lugs 3 and 6 are active.
It renders the treble pot, bass pot, decade and pickup selector active.


When tone 3 mode is selected (lug 4 and 7), its just pickup selection and decade before volume and out.


Now, when you read the Gibson Schematic, knowing what lug the tone selector affects, is that what you read too ?

Let me know.

[newey]

Now, when you read the Gibson Schematic, knowing what lug the tone selector affects, is that what you read too ?

Let me know.

That's what the Gibson schematic shows all right, but not what the other guys description says, as he claims the Decade is disconnected at position 3.

The buss used makes this more confusing than it needs to be. I have no idea what the purpose of that is, particularly since several of the connections are not used anyway.

1 and 8 are always active in the flow.

These are the "common" or "pole" connections. The switch is a DP3T switch ("double pole, triple throw") and is the same as is used on a std. Tele and on vintage Strats.

One pole is comprised of lugs 1 through 4 (as shown on your diagram); the other is 5-8. the two poles are wired together in this scheme but they don't have to be, they can be used independently.

lug #1, the common lug, connects to lugs 2,3, and 4 in succession as the switch lever is pushed through its rotation. At the same time, lug 8 is connected to 5,6, and 7 in succession.

[pemorin]

Jun 4, 2011 7:25:32 GMT -5 newey said:

That's what the Gibson schematic shows all right

All right, I think at this point I will take that and run !

Maybe the guy just explained it improperly, as even his schematic for Tone 1 seems to not connect the decade with the flow to the output, and on Tone 3, the flow goes directly through the decade to reach the other stuff.

Ok last one : I think in your first reply, you were telling me i should use the clockwise lugs of the pots. This is what seems to be done for volume and bass pots in the other unmodified (afaik) pictures, but not for the tone. Both seem to use the counterclockwise lug.

Now, being a rookie solder flinger (that's what the forum gives me as a title, so it must be true ), I would be tempted to do the same. Can you explain to me the difference that exist between both lugs ?

Thanks a lot for your help, I feel like a 1st grader asking that last question

[newey]

Now, being a rookie solder flinger (that's what the forum gives me as a title, so it must be true ), I would be tempted to do the same. Can you explain to me the difference that exist between both lugs ?

Well, I came up with the titles so I guess you can blame me for the moniker. Keep posting, it'll change soon enough . . .

The schematic from Gibson doesn't label the lugs, but the "hot" to the CW lug would be the usual way to wire it.

The difference is in right vs. left handedness. If you're a righty, you want the knob to turn clockwise to go to "10"; reverse the outside lugs on a pot and it's wired lefty, where "10" is all the way CCW.

If you wire it up and the knobs work backwards, you just have to switch the wires to the outside lugs.

It doesn't have to be the one way, it will just work opposite if wired backwards. I purposely wired my single HB Strat with the Vol knob wired lefty, since I kept hitting it with my hand while strumming. Wired righty, hitting the knob turns it down or even off, which I found annoying. Wired lefty, if I hit it, it turns up if I had it turned down to start with, it stays at 10 if it was there already.

Took me a while to get used to it at first, but after awhile it became like second nature.

[pemorin]

Well thanks a lot for everything Newey, you've been extremely helpful. I'll be doing the modifications soon, so wish me luck.

If you wish to see my restoration process, I am documenting it over at the My Les Paul forum :
www.mylespaul.com/forums/gibson-les-pauls/99478-my-lp-professional.html

Thanks !

[newey]

A very detailed thread on your restoration project. +1!

And, on the related wiring thread you gave me props, so thanks! But lets's be sure it works as intended before you thank me too much!