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Problems with a set of active EMG Jazzes

Discussion in 'Pickups & Electronics [BG]' started by Hambone, May 16, 2005.


  1. The Jazzwick project still sits on hold as I try to figure out this devilish problem. Here's the scoop:

    This is a pair of ebay pups that came with new pickup leads but a used control harness. I desoldered all of the pots and cleaned them up before installation. After installation things weren't going well. First no sound, then after diagnosing a cold solder joint and a small detail in wiring that went unnoticed because of a worn fold in the instruction sheet right over said detail I finally got sound to come out but it was dodgy and I didn't seem to have any volume control for either pup. I chalked all those problems up to the used harness and ordered up a new one. When that arrived, I was surprised to find it already soldered up so I installed it and the problems continue. First, though the output jack is wired correctly, the signal will only come out if the plug is pulled out so the tip detente is lodged on the first contact. This jack is wired precisely as the other one but doesn't work the same. Second, I still don't have any volume control for either pup. I do have tone control and both pups are working but neither of the pots affect their pups volume. :confused:

    I'm leaning towards thinking that there's something wrong with the internal preamps in these pups. How both of them got that way is anybodies guess but since the harness is new and the wiring isn't complicated at all, I'm at a loss to come up with anything else.

    Any idea's?
     
  2. jja412

    jja412 Fine gear enthusiast

    Feb 2, 2004
    St. Louis
    I come up with the same conclusion, Allan....probably the internals??
    Did you put the quick connects on the right way???? :meh:
    The sets are so easy to wire that it's probably not user error...you know what you are doing. Perhaps contact EMG??? I have no idea. Thanks for the neck inserts, by the way. They worked perfect!
     
  3. Whew, glad to hear it (about the inserts) - The last guy that tried them split his neck! :rolleyes: That's why I removed the ad. :scowl:

    The connects are on the right way and haven't been moved since the first setup - only the controls were changed in the cavity. Since I get sound, I'm sure the power is on the correct contact. If it wasn't, I shouldn't get anything from that pup. The other two leads are just hot and ground like any other.
     
  4. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    Screw the harness and run the pups straight to the jack. Your main concern is the pups, and those you suspect so eliminate all but the essentials and check them out so you'll know.


    Took me the rest of this to get to the above so I just cut it and stuck it first - but you can read this junk if you want :)

    I've had many sets of EMGs and never had a problem - and some were tortured as evidenced by appearance. Given they have clips, yours are later model and I suspect highly unlikely to have internal problems. I know it's not uncommon for external pre's that are about 10 years old to have problems but I suspect the internal stuff is pretty impervious. Unless somebody fired them up to a diehard, to my knowledge they can't be damaged.

    But I've never seen where those EMG pup clips were anything but a pain. I even had a late model set some dude had soldered leads to the pup tangs cause he didn't have the clips - did a hell of a job I might add (I used them and sold them that way and I'll bet they're still that way and working fine). You can put those clips on backwards but they're clearly marked in my recall.

    First I'd take a meter and check the clips for continuity to make sure they're not screwed up. Then I'd take an input plug and check the jack to make sure it's right. You can just use a naked input - I usually use one I keep laying around from one of those cheap chords that went South and I clipped the end off and stripped the wires.

    If you're talking about a standard EMG vol/vol/tone harness - there's really noting else to go wrong if it's wired correctly.

    EMG site has the wiring scheme.
    http://emginc.com/downloads/wiringdiagrams/J_models1.pdf

    Make sure the battery clip negative is going to the stereo jack nuetral and not the ground. Ground goes to the jack ground and vol to the hot of the jack. The red lead from the pups joins with the Battery clip red and that's it.

    Make sure the batteries good - check it with the meter.

    Make sure the chord is good.
    =====================

    Reading back through the first post, sounds like a wiring problem to me. I could be wrong but if you've got a toasted set it'll the first set of active EMGs I've heard of gone bad.
     
  5. I just read your post Ron,

    OK simple question and it will cut directly to the heart of the matter here...

    Would a reversed plug at the pickup account for the pup having a signal with tone control but without volume control?

    Because here's the thing - the harness is absolutely correct - it's a factory wired harness and I've retraced it's circuits and it matches every schematic (now 2) that I've seen from EMG. The plug has been attached to the pup in the correct orientation according to these instructions but that's referencing the plug alone - not the orientation of the wires going into the plug. The other end of the pup leads are correct - well, because I did 'em :D. After all, other than the battery lead, they aren't any different than any other pickup. So that leaves the possibility that the pup leads could have been made wrong (this hasn't been checked and verified) or the 3 contacts on the bottom of the pup are reversed - an unlikely yet verifiable condition. The only other possibility is that the pup lead should be installed different than what has been illustrated in the instructions, in which case I would have put them on wrong from the beginning - another unlikely scenario.
     
  6. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Don't know, never done it and I'm a do and find out guy, not a smart one. Dharmabass would probably know - and others.

    But I do know, somebody else posted a similar issue - only he has a P bass and instead of getting vol/tone, he's getting vol/vol. But I think he dropped it into the stock harness on an artcore. Maybe EMG's QA is not up to snuff but I haven't heard anything - now Dimarzio, those guys have had their troubles.

    By "plug" I assume you're talking about the quick connects to the pup. Not sure if his had those or not. I don't see anywhere where you say what kind of pups they are. The only EMG's I have at the moment are a set of old PJ's without the quick clips. But assuming they're P or J, the pups should have 3 tangs (and so the quick clips - unless they do HB's different) equating to the white(hot)/ground/and red (battery lead) of my pups. A continuity check will show markedly more between the hot and ground tangs than between the battery and the other two, so you can isolated the battery lead which only leaves two to go wrong. You should get the same meter response in connecting the clips and reading the end of the leads. If not, I'd check the quick clips from end to end to make sure they're not screw up.

    If all seems well then I'd take just one pup and wire it straight to the jack and see how it sounds, if funky then swap the leads at the jack. Probably would be a good idea to swap them anyway cause you won't damage anything in the process and their may be a subtle difference.

    If your good to go, do the other pup the same way beginning to end. If you're not good to go, I'd definetly check the jack.

    That's all that comes to mind.
     
  7. Nino Valenti

    Nino Valenti Commercial User

    Feb 2, 2001
    Staten Island NYC
    Builder: Valenti Basses
    I would try to reverse the Quick Connect clip on the pickup.

    EMG recently chaned the look of the clip and when I installed a set in a bass, I put the clip on backwards and the problems you're having seem to be the same problems (sound output) I had.
     
  8. oooo, now there's an interesting piece of info! These clips were new ones sent with the pups even though the pups were used. Verrry interesting...

    [heads out to shop]

    Just got back in from the shop to try switching the plug polarity. This is absolutely the dumbest thing I've seen in a long time. The pups work exactly like they did before - no change. What the hell is this? Does it not matter which lead the voltage gets applied to? Both pickups work and both have tone control but neither have any volume control through the pot - with the plugs attached in either direction! The jack is wired correctly but there is still no signal to the tip - the only time I get a signal is by pulling the plug out to where the tip engages (what would be) the ring contact. This schematic is precisely the one that is being followed:
     
  9. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    now I see what you mean by pulling the plug out to the tip - you're talking about the cord input. Do the thing I suggested in the first and second post and check the jack with a meter, then check the a test plug with a meter (as preveiously suggested), cause it sounds like the problem may be in the plug not making proper contact with the jack. Also, I don't suppose you're using a cord with a stereo plug (two black bands on the top) instead of mono (single black band). That may alter the alignment with the jack which is designed for mono input.

    It almost sounds like what EMG has done with the quick connects is to make them so they're stooge proof and can't be plugged in backwards - but it you reverse the plug you reverse the connections to made. It does matter which lead goes where.

    Also do the meter check on the quick connects I suggested. I really doubt there's any problem with those pups. I've just never heard of an active EMG gone bad - though no doubt it's happened.
     
  10. I've done continuity checks nine ways to sunday and after going down a couple of forked roads, I think both volume pots are faulty. What I've found is that I've got continuity between the case and the center tab no matter where the the knob is turned. This has the effect of bypassing them and going straight to the tone pot. In this case I don't think that is working either. When I took the entire assembly apart I checked it and I don't get any signal through it anywhere in it's rotation. I've probably been hearing things with the tone pot :rolleyes: I've done some comparing with other new pots I've got here in the shop and except for a difference in rotation, I could always get an on/off condition from them. None of the EMG pots worked that way.

    So does this sound right?
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Allan,

    not sure if I'm following you correctly but there shouldn't be any continuity between the center lug (or any of the lugs for that matter) and the pot case unless one of the lugs is somehow connected to the case (ie through the pickup when the pups are connected to the pot, grounding the right lug to the case as is commonly done, whatever).

    I check pots for sweep by connecting to the center lug and either of the other two lugs - if I get sweep on the meter, the pot works. I've got an old EMG standard vol/vol/tone harness I get sweep on all 3 pots.

    Nothing unusual about hearing things either - common place in tone searching. What's uncommon is admitting it :- )

    Oh yeh, so I'm guessing you haven't ran a pup straight to the jack yet to rule out the pups?