Lace aluma x-bar hum problem

Discussion in 'Pickups, Electronics & General Tech' started by Riker_Maneuver, May 20, 2017.

  1. Riker_Maneuver

    Riker_Maneuver SS.org Regular

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    I have a strandberg that has the lace aluma xbar 3.5's. I had to have the vol pot replaced due to it cutting out and cleaning with deoxit not doing the trick. The shop replaced it and I'm getting a hum when I touch either pickup when selected. The hum goes away if I touch the strings. I took it back to the shop and they couldn't find anything wrong after testing it with a multimeter they seem to think that it was grounded properly. I don't know if it's just the nature of the pickups to do this, but I somehow doubt it. None of my other guitars do this. I've emailed Lace asking for a wiring diagram for a 2 hum, 1 push/pull vol, 1 tone 3 way blade diagram but haven't received a response. I'm hoping that someone here with more knowledge can tell me based on these pictures if it appears wired correctly. The only thing I can think of is that the bridge ground wire may not have a good connection to the bridge? Anyway, hoping someone can give me come insight into what's going on.

    https://goo.gl/photos/S8iMfR9mtiihbKxP9
     
  2. rami80

    rami80 SS.org Regular

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    From the photos it looks like a lot is grounded to the push-pull pot but I don't think there is any ground wire going from it to the bridge.
     
  3. Riker_Maneuver

    Riker_Maneuver SS.org Regular

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    The black wire at the top of each photo is the bridge ground, and it doesn't appear to be loose by slightly tugging. This is very perplexing to me. Thanks for taking a look.

    Just checked with my multimeter with one probe against the input jack tested strings to jack, pickup to jack, and bridge to jack. Strings and bridge gave a reading, pickups did not. However when I tested the mounting screws on each pickup, 1 out of the 4 screws per pickup gave a reading but not the pickup itself.
     
    Last edited: May 20, 2017
  4. rami80

    rami80 SS.org Regular

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    I see there is a ground to the back of the pot going to the last lug. Can you check if there is continuity between the pot itself and the switch on top of it?
     
  5. Riker_Maneuver

    Riker_Maneuver SS.org Regular

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    So I went out and bought a new multimeter that has an audible continuity setting and started going to town checking everything against the input jack. What I discovered was that the ground soldering on the back of the pot was pretty spotty. Some place triggered the continuity beep other spots didn't. So I took out my soldering iron and re-soldered everything to ground on the pot and now the hum is gone! Or so I thought. It was gone, but came back. When it does, there are clicks and pops then it either goes away or come back when I touch the pickup. I drew up a wiring schematic of how it's wired. It doesn't look anything like how lace suggests, so I'm not sure if the shop to some liberties with the wiring or if they just copied the Strandberg factory wiring it came with.

    http://imgur.com/a/2qU4Y
     

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  6. Lace Music Products

    Lace Music Products SS.org Regular

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    Hello Riker,
    From reading your posts, i would focus on the replaced pot. Generally, when more than one pickup develops a hum, after a component has been changed, it's usually some common point in the connections to that component. Try re-soldering all the connections to the pot. Make sure that there is a ground connection between the pot and push pull switch. On the Alumitone, the black anodizing is non conductive, but usually one or more mounting screws makes a ground connection thru the anodizing. If one screw is conductive the the jack, the that one should be fine. Hope this helps
     
  7. Riker_Maneuver

    Riker_Maneuver SS.org Regular

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    Hello and thank you for the reply! I rewired the vol pot so that it now matches the Lace diagram. I also soldered a piece of guitar string from the pot to the switch just to make doubly sure there was a solid connection. I have continuity through out according to my multimeter. Still had the hum, but didn't seem as bad as before. I then check the pickup mounting screws for continuity and none of the ones on the bridge pickup had it (which is pretty much where I am having the hum) and then checked the neck pickup and had one screw that had continuity to the jack and to the bridge. I took one mounting screw out of the bridge and then sanded a bit of the coating in the pickup screw hole off and replaced the screw. I now have continuity from that screw to the jack and to the bridge. I'll have to test everything out for a few hours to see if that finally resolves it and I hope it does seeing as the neck didn't really have the problem. I'll report back on my findings.

    One other question off-topic - What pickup height do you recommend for the x-bar 3.5's? I can't get them any closer than about 1/4" where normal passives I tend to have at about 1/8". The output is rather low and I'm not sure if that is the nature of the pickup or just the distance from the strings. I can't really find any info regarding pickup height for these pickups on the Lace site
     
  8. Riker_Maneuver

    Riker_Maneuver SS.org Regular

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