EMG SG/LG Jazz wiring diagram?

[travismoore]

Hi,

I am trying to find a wiring digram for some old EMG SG/LG pickups. I have found the diagram for the newer solderless version on their site but this involves a circuit board and is a fair amount more complicated.

All it consists of is the 2 pickups, Tone/Vol/Vol pots and a 9V battery connecter. I have done a fair bit of soldering in the past I just don't really know how its meant to go together as a circuit.

I also have another question, does anyone know where I can find a circuit for a low battery LED. Only one I've found so far I know will work great but is quite expensive.

http://www.east-uk.com/index.php/all-products/bli-01.html

Cheers,

Travis

[curtisa]

Is the LG/SG anything like the LJ/SJ pickups?

At the bottom of this page is something that sounds roughly like what you're after. Pots would be 25K log taper, tone capacitor 0.1uF or to taste.

I also have another question, does anyone know where I can find a circuit for a low battery LED

Are you after a diagram to roll your own, a kit or a pre-assembled module? Lots of schematics floating around for low battery monitors. The ones that are the most useful to you will be circuits advertising low battery consumption, like this or that (click on "figure 1" to see the diagram). The second one actually sounds enough like the module you linked to above for it to be fundamentally the same, except for the massive price mark-up. Your local electronics DIY/hobby store may have kits or pre-assembled modules for sale that will work, but size and/or power consumption may be limiting factors. Other pre-assembled modules exist but IMO are all overpriced for what they do.

[travismoore]

Perfect that is exactly what I was looking for. Many thanks for your help

[travismoore]

I have been wiring up the bass today and as far as I can tell I have everything correct but I am getting no output from the bass at all. I would appreciate if anyone could take a look at it.

The red wire that runs off to the right is going to the battery and is connected on the left to both the red wires from the pick-ups.

Edited January 3, 2014 by travismoore

[curtisa]

Few things you can check:

• Is the battery and/or battery clip known good?
• Are the pots known good?
• Were/are the pickups known good?
• Are there any shorts between the white signal wires daisy-chained to the output jack and the cases of the pots?
• Is the jack wired correctly (signal output from tone pot to Tip, battery negative wire to Ring, ground from pots to Sleeve)?
• Could you have applied too much heat to the braid of the pickup wires when attaching them to the pot shells and melted the insulation around the inner signal conductor?
• With the bass plugged in and a battery fitted can you generate any buzzing noises if you touch the wiring with your fingers?
• If still no joy, try unsoldering one of the pickup signal wires (eg middle lug of left pot in pic above) and temporarily connect it to the Tip of the output jack. This connects the pickup directly to the output, bypassing the volume and tone pots. Plug the bass in and see if the directly-connect pickup works. If it works the fault is likely in or near the volume pot that pickup was previously connected to and/or the tone pot. Repeat for the other pickup.

You'll probably need a multimeter if you're still having trouble beyond the above suggestions.

[travismoore]

I did have it all working in another bass but they have been sitting in a shoebox for a couple of years since then. There are no signs of corrosion etc, So I can only assume they work, the only difference is when they where installed previously they where hooked up to a barrel jack.

I can't see any shorts in the white wire.

Double checked the jack - Tip is connect to tone pot, Ground to Sleeve and Battery Neg to Ring.

I have connected it all up with battery and touching the wires gives no found what so ever. I assume this means the circuit is not complete?

I will try your other suggestions and report back, thanks for the help.

Also just to make sure I am correct, I have wired the red wires from the neck and bridge pick-up wired into the red wire from the battery. Is that correct?

Edited January 3, 2014 by travismoore

[travismoore]

Ok, so I just wired it up with only the pick-up and the battery and I am still getting nothing when playing the strings but if I touch the pick-up or anywhere in the circuit I am getting some buzzing. Not sure if that is good or not?

[curtisa]

You still need the braid from the pickup lead to go to ground via the Sleeve tab on the output jack - the ground connection is missing in that 2nd pic.

Also just to make sure I am correct, I have wired the red wires from the neck and bridge pick-up wired into the red wire from the battery. Is that correct?

Unless EMG changed their wiring colour scheme over the years, I'd say yes - all reds joined to the red (positive) of the battery clip.

If you could get some buzzing with the pickup direct to the output jack, and nothing at all with the original circuit, you most likely have a short between the signal wire and ground somewhere in the original wiring (buzzing is a good thing - proves it's possible to get some kind of signal out of the bass).

Edited January 3, 2014 by curtisa

[travismoore]

Just wired up the braid wire to the ground and tested it and I get nothing, no sound through the amp and nothing if I touch any of the components. Does this mean that there is an issue with the input? Only sound I got was a pop when I unplugged the battery.

Also just to rule it out I stripped back the white wire with the braid to see if I had melted through to the wire in the core and it was fine.

I am going to order a multimeter so that will hopefully make life easier.

EDIT:

So I have worked out what my problem is.... and I feel totally stupid now and I can't believe it didn't dawn on me before but the clip that does clips on to the underneath of the Pick-up can in fact be put on the wrong way around.......

It is now working with the single pick-up. going to wire everything up now and I have a feeling its all going to work.

Edited January 4, 2014 by travismoore

[travismoore]

Ok so a little update, I put it all back together and it still doesn't work so maybe putting the clips on upside down was only one of the issues. I have soldered it all up with just the one volume pot and the tone pot now and still nothing. So far the only working configuration is with just the input jack and pick-up. The multimeter is arriving in the next few days then I can test things in a less trial and error kind of way.

Current (not working) wiring:

[curtisa]

If both pickups work direct to the output jack the fault has to be in the volume or tone pot. Visually it looks OK, gotta be something sneaky.

From your pic it's a bit hard to tell, but is the top lug of the middle volume pot (with the black wire soldered to it) also soldered to the case?

Are the pots valued at 25K (not 250 ohms or something unusual)?

If you're happy to try another stab in the dark, you can also try removing the tone pot from the equation by disconnecting the two white wires from the middle lug of the tone pot (leave the two wires connected together but hanging in mid air). The remainder of the battery and pickup wiring can remain as-is. If there's still no sound the fault must be in the volume pot.

[travismoore]

Finally got a chance to look at this wiring again, with my new multimeter this time. I have checked the pots and they are all "15A 25k 0240 S" and the the earth soldered to the middle volume pot is definitely soldered to the wire as well as the pot.

I rewired everything and went the through with the multimeter testing. I tested both volume pots (by touching the terminals to the outer of the white wire from the pick-up and the inner one that's connected in the centre terminal). They are working fine but when I did the same to the tone (with the black earth wire and white wire) and that is where the issue seems to be. I am getting no reading what so ever, So I can only assume there is a problem with that pot or maybe the capacitor?

Edited January 19, 2014 by travismoore

[curtisa]

Need a bit more information. I'm a bit unclear about how you're testing the pots. Assuming the wiring hasn't changed from your last photo (one pickup, one vol, one tone) try these tests:

1. Unplug the pickup connector and battery. Wind the volume and tone pots to maximum. Set your multimeter to ohms and connect the probes to the two outer lugs of the volume pot - should read 25K ohms.
2. Connect the probes between the centre lug and upper lug of the volume pot - should read 25K.
3. Connect the probes between the centre lug and lower lug of the vol pot - should read 0 (or close to)
4. Rotate the volume pot and repeat steps 2 and 3 at various points of rotation - you should see the resistance recorded at step 2 gradually reduce to 0, and resistance recorded at step 3 gradually rise up towards 25K.
5. Repeat steps 1-4 for the tone pot - should get exactly the same results.
6. Measure between the tip and sleeve lugs of the jack socket - with the pots at max you should read 25K. With the volume at minimum you should also read 25K.
7. Connect one probe to the sleeve lug of the jack and use the other probe to check for continuity to the various earth locations - your meter should read 0 with the other probe touching the upper lug of the volume pot, the case of each pot, the braid of the pickup wire and (if you can fit the probe in) one of the sockets in the pickup connector.
8. Connect one probe to the tip lug of the jack and use the other probe to check for continuity of the signal (white) wire - meter should read 0 with the other probe touching the middle lug of each pot.
9. Plug in a battery and a guitar lead (leave the other end of the gtr lead and the pickup disconnected at this stage). Set your multimeter to measure DC volts. Place one probe on the sleeve of the guitar cable and the other probe on the red wire of the pickup connector - meter should read 9V (or whatever your battery is currently charged to).

See how you go.

Edit: corrected test 6.

Edited January 19, 2014 by curtisa

[travismoore]

Sorry I mean't to post a picture in my previous post I have it all wired up again like so:

http://i24.photobucket.com/albums/c47/travis_moore/DSC_0157_zpse260b692.jpg

Used my multimeter and got the following results:

Neck Volume Pot Full - Top & Centre - 24.8

- Centre & Bottom - 0.0

Neck Volume Pot Off - Top & Centre - 0.0

- Centre & Bottom - 24.9

Bridge Volume Pot Full - Top & Centre - 24.9

- Centre & Bottom - 0.0

Bridge Volume Pot Off - Top & Centre - 0.0

- Centre & Bottom - 24.8

* Tried them at various in between volumes and it seemed to be consistent or from what I could tell.

5. Did same test on tone pot and got similar results

6. Input jack also read around 25k at Min & Max volumes

7. Checked earth from input jack sleeve lug at all points including inside pick-up clip. All read 0

8. Check signal wire at all points, all read 0

9. Checked from sleeve of lead to red wire of pick-up clip and was reading the same voltage as battery (8.25 ish)


After all this as everything seemed to be functioning I wired up the bass to test it and to my surprise the bridge pick-up was working so I decided to mess with the pots a bit and I realised the the neck pick-up was working but the volume pot would ramp up to a point then all volume would cut out. I also found that the volume for the bridge p/u will get loud then quite then loud as you turn it.

I put some switch cleaner in all the pots because one was also a bit scratchy and that seems to have fixed the neck p/u volume issue as it is now nice and smooth. The bridge p/u volume however still has the same issue.

The tone pot is also functioning just fine but I am a small amount of hum when its all the way off and a lot of hum when its all the way on. There is no grounding to the body or the bridge at the moment though so I take it that may be the issue? Should I ground to the body and bridge and if so what pots/wires should I attach them to?

Here is a video of the issue:

http://youtu.be/x5_GvUsiTP8

Thanks again for all the help

[curtisa]

I'd say your pots are shot and should be replaced if they're cutting in and out at full rotation. Otherwise it sounds like they're operating as expected.

Regarding the buzz in the tone pot, it may be that you have insufficient shielding inside the control cavity. Is the cavity lined with conductive paint or copper/aluminium foil? Any shielding in the cavity needs to be grounded via the sleeve of the output jack. If you can make the buzz change in intensity by hovering your hand over the wiring or moving the bass around the room your shielding needs sorting out.

The tone pot is unlikely to be the cause of the buzz, but rather the method of revealing it. As the tone pot is wound down to minimum the filtering action of the tone circuit reduces the apparent intensity of the buzz, similar to winding down the treble control on your stereo while playing a noisy vinyl LP.

[travismoore]

Ok sure thing I will replace the pot and insulate the cavity. Thanks so much again for your help, it is much appreciated.

[travismoore]

I am back again, I have finally got to putting in the new pots but I am still having some issues unfortunately. I ended up replacing all three pots because I was having a lot of issues finding pots to match the EMG ones.

Anyway while I am getting sound and the tone pot etc is working fine the output volume seems to be greatly reduced. I would say its 3/4-1/2 what it used to be with the original passive pick-ups. Seems a bit strange as surely an active bass should have a louder output?

I can only assume that maybe when the volume pots are at full they aren't at 25K as they should be? I am going to test them but I wanted to get an opinion first just in case it is actually something else?

Current Wiring:

I also have another issue, I have shielded the bass with copper tape but I think I may have done something incorrectly as I am still getting a large amount of noise. I insulted the control cavity, cavity cover, pick-up cavitys and then ran wires between them. Only thing I didn't insulate is the batter compartment, I thought that would be ok as its a plastic container? Here is a picture:

[Prostheta]

With EMGs I wouldn't bother with insulating, to be fair. The internal differential pre-amps in the pickups reject noise well enough, and the fact that the rest of the circuit runs at low impedances helps keep everything quiet.

Is the socket wired tip/hot, ring/battery negative, sleeve/grounding? It is entirely possible that the pots are screwing up your output if they appear faulty.

[travismoore]

With EMGs I wouldn't bother with insulating, to be fair. The internal differential pre-amps in the pickups reject noise well enough, and the fact that the rest of the circuit runs at low impedances helps keep everything quiet.

Is the socket wired tip/hot, ring/battery negative, sleeve/grounding? It is entirely possible that the pots are screwing up your output if they appear faulty.

I didn't have the insulation in their previously but added it because there was so much noise, Unfortunately there is still a lot of noise. The input is fired up as you described, I guess I will have to get out my multimeter and test the pots so see if they are working correctly

[Prostheta]

Bypass the pots. Straight to the jack. Pull the pots out of the equation.

[curtisa]

Anyway while I am getting sound and the tone pot etc is working fine the output volume seems to be greatly reduced. I would say its 3/4-1/2 what it used to be with the original passive pick-ups. Seems a bit strange as surely an active bass should have a louder output?

I can only assume that maybe when the volume pots are at full they aren't at 25K as they should be? I am going to test them but I wanted to get an opinion first just in case it is actually something else?

Battery known good? Distance of pickups to strings? Were the original pickups hot output to begin with? Are these particular EMGs marketed as a medium output set?

Pots being the wrong value is a possibilty, but should be easy to confirm before ripping apart all your hard work.

I also have another issue, I have shielded the bass with copper tape but I think I may have done something incorrectly as I am still getting a large amount of noise. I insulted the control cavity, cavity cover, pick-up cavitys and then ran wires between them. Only thing I didn't insulate is the batter compartment, I thought that would be ok as its a plastic container?

Shouldn't need to shield the battery compartment. Your shielding looks very thorough. You mention that you've run wires to all sections of shielding, but have you verified that they have continuity to the output jack shield tab (shielding needs to be grounded to be effective)?

Maybe the remaining noise is external to your bass? Does the noise change in proximity to a computer monitor, fuorescent lights, lighting dimmers, laptop powerpack, fridge etc? Does the noise change when plugging in to an amp in a different room of your house? In a different house altogether? What about swapping to a different amp or guitar cable?

[Tim37]

You dont need to ground the strings and shielding with emg's in fact they say on there web site not too. You could be grounding through the pots if so use some electrical tape to insulate them.

The volume could be few things but specific to emg the pickups need to be closer to the strings. And if everything is right and your still not happy tiss in another battery and make it 18v

Also if your having problems with finding 25k ohm pots just use larger ones it wont hurt a thing.

[travismoore]

Thanks for the responses guys,

You where right about the hum Curtisa I sit with my bass right near my PC tower, I have tested it an if I angle the bass toward it or move it closer the noise increases. If I stand up or go anywhere else in my room there is no noise. So that's one problem solved.

I have tested it with a brand new battery and it is the same. Just measured and the E string is about 2mm from the pick-ups I think any closer and the string would hit the pick-up and create issues.

It originally had Seymour Duncan's in but it was like that when I bought it and I can't see a model number on them so not sure if they had a hot output. That being said my fender is now much quieter than my other basses and it used to be about the same. If I use my audio interface as an example for most of my basses I put the volume to about 12 o'clock - 2pm area before it starts clipping. Since putting the EMG's in I can put my audio interface at full volume (5pm) and no matter how hard I play it won't clip. Can't see any markings on the EMG's to indicate they are lower output they are the standard LJ & SJ set.

These are the pots I got:
http://www.thomann.de/gb/allparts_poti_25k.htm
They came in "allparts" packaging but actually say "alpha" on the back but definitely state they are 25K

I was thinking about it there is another possibility for what is causing the issue, I had some issues with the battery compartment that I put in. Only after I made the hole in the bass for it I realised that the way it was designed doesn't allow for the battery to actually clip into the battery clip when you close it. Anyway in order to get it to work I had to hack things a little .... I used two parts of a bent up paper clip to make terminals and padded the inside of the box at the back so it would push up against them. Then soldered the wires directly to the paper clip. Maybe not the most elegant solution but I had been working on the bass that day from when I woke up until around midnight so seemed like a good idea at the time. Is it possible this is restricting the flow of current?

Picture:

Edited March 24, 2014 by travismoore

[Prostheta]

+1 on the 18v mod. It will not increase output though, unless your signal was hitting the rails. The older preamp design prior to the newer EMG-X pickups didn't have as much headroom from what I can make out. This mod will not solve your current issue. No joke intended.

[curtisa]

You dont need to ground the strings and shielding with emg's in fact they say on there web site not too.

The reason given by EMG for not grounding the strings has nothing to do with noise reduction. The claim by EMG is that it is a shock hazard due to you being grounded via the strings and then touching something ungrounded (or differently grounded than your instrument). Personally I'd want all exposed metal objects connected to electrical equipment to be at the same potential no matter what. If you're ungrounding your guitar in an attempt to avoid shocks from other connected equipment the potential for shock is still there and should be dealt with at the source.

Shielding in the control cavity isn't mandatory with EMGs, but won't be detrimental to noise performance of the instrument either. Shielding the pickup cavities shouldn't be necessary and can be removed if you wish.

It originally had Seymour Duncan's in but it was like that when I bought it and I can't see a model number on them so not sure if they had a hot output. That being said my fender is now much quieter than my other basses and it used to be about the same. If I use my audio interface as an example for most of my basses I put the volume to about 12 o'clock - 2pm area before it starts clipping. Since putting the EMG's in I can put my audio interface at full volume (5pm) and no matter how hard I play it won't clip. Can't see any markings on the EMG's to indicate they are lower output they are the standard LJ & SJ set.

You may need to get in touch with EMG and ask them what the difference is between the LG/SG and LJ/SJ pickups. It almost sounds like the LG set you have are active pickups with a high impedance output and don't use the low value pots normally supplied with active EMGs. It may be that the LG/SG set require higher value pots in order to develop the full output, or (hopefully not) require an additional preamp to boost the pickup outputs up to full throttle.

These are the pots I got:

http://www.thomann.de/gb/allparts_poti_25k.htm

They came in "allparts" packaging but actually say "alpha" on the back but definitely state they are 25K

Alpha make most of the world's supply of generic pots. You can probably pick them up at your local electronics DIY supply store for a fraction of the cost charged by Thomann.

I was thinking about it there is another possibility for what is causing the issue, I had some issues with the battery compartment that I put in. Only after I made the hole in the bass for it I realised that the way it was designed doesn't allow for the battery to actually clip into the battery clip when you close it. Anyway in order to get it to work I had to hack things a little .... I used two parts of a bent up paper clip to make terminals and padded the inside of the box at the back so it would push up against them. Then soldered the wires directly to the paper clip. Maybe not the most elegant solution but I had been working on the bass that day from when I woke up until around midnight so seemed like a good idea at the time. Is it possible this is restricting the flow of current?

Unlikely. According to the LJ datasheet each pickup draws 80 microamps at 9V. In order to reduce the output so significantly at that current draw your battery box would have to be introducing an additonal 20-40Kohms of impedance at the battery terminals. If you want to verify, you can measure the battery voltage at the pickup and at the battery box. If the volts are practically the same then your makeshift terminals are working fine. You'd probably notice other problems first, such as distorted output or intermittent operation.

+1 on the 18v mod. It will not increase output though, unless your signal was hitting the rails. The older preamp design prior to the newer EMG-X pickups didn't have as much headroom from what I can make out. This mod will not solve your current issue. No joke intended.

Indeed. The EMG 18V mod is akin to going to your local and asking the landlord to pour you a 10oz beer in a 1 pint glass. The bigger glass is capable of holding more, but you've still got the same amount of beer to start with.