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Repairing electronics in old Mako bass

Discussion in 'Pickups & Electronics [BG]' started by CGEffex, Dec 2, 2013.

  1. CGEffex

    CGEffex

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    First of all I must apologize for my amateurishly little knowledge of bass guitars in and of themselves, but I'm new to the whole bass scene. I'm also sorry if I picked the wrong forum for this topic, I thought I might put this in 'Hardware, Setup, and Repair', but my issue is electronics related so...here I am. Oh well...That being said, here's my story and dilemma:

    For a while now, I've been interested in purchasing a bass guitar. I've been playing acoustic guitar for around a year now, and it has been a very enjoyable self-taught learning experience. I hadn't been planning on buying a bass (it was sort of a back-of-the-mind thing), but when I happened across a nice looking bass in a thrift shop for a ridiculously good price, I couldn't resist.

    About the instrument itself...as of yet, it is sort of unidentified. When I bought it, I assumed the 'Mako' name on the headstock referred to some kind of little-known cheap guitar manufacturer, but after doing a little research I now suspect it may be of the (infamous?) Matsumoku line. I encountered some difficulty registering at the matsumoku.org forums, and so I came here hoping (mainly) to figure out how to repair a (likely infinitesimal) electronics problem, and possibly, with any luck, happen across a user who might know something about the instrument's origins.

    They say a picture is worth a thousand words, so here she is in all her glory:
    [​IMG]
    Except for that hole some fool gouged into the body below the tone knob (I don't know why someone would do that, there's no electronics you can access through that hole that you couldn't access through the back panel) the guitar is in beautiful shape. Of course there are a few scuffs and nicks here and there, but overall it's fine.

    Now here's the dilemma:
    [​IMG]

    (I'll refer to the picture above as I explain the problem)

    When I first got the guitar home, I cleaned it up (dusty, grimy, sticky!) and first thing after that I tested it out by plugging it into my Tascam DR-03 audio recorder via a 1/4th" to 1/8th" plug and 1/8th" cable (The recorder only takes in 1/8th"), setting the recorder to mic level audio input, plugging my headphones into the output, and turning on the pre-record mode (in which I can essentially hear what would be recorded if it was recording). In this way, the recorder essentially functions as an ad-hoc headphone guitar amp.

    To my great surprise, the guitar seemed to work fine, although there was a noise/buzzing from what sounded due to grounding problems. I also noticed that although the volume knob (leftmost knob in the picture) worked fine (except for what sounded like a bit dirty pots), the tone knob (rightmost knob in the picture) didn't seem to do much but change the 'tone' of the noise/buzzing.

    As you can see from the picture, there is one (brown striped) wire loose and I am mostly sure that is the cause of my problems. I'm also fairly sure it should be soldered back onto that third (unconnected) terminal on the tone pot, but I'm not positive and here's why:

    - With the guitar connected to my computer (I later used my computer's mic in as my amp setup) and the unconnected wire left unconnected I get a mild buzzing while the volume is up that goes away when I touch the volume knob and gets louder when I touch the tone knob. (The noise also goes away when I touch the metal of the 1/4" jack plugged into the guitar.

    - With the guitar connected to my computer and the unconnected wire held where I believe it should go, there is even more buzzing. That only goes away a little when I then touch the volume knob. (Shouldn't all buzzing go away when I put the wire where it goes?). Also, THIS buzzing get's even WORSE when I touch the strings.

    So my main question is: What to do. Should I solder the wire where it seems it should go and go from there (although it seems illogical), or what? (Will that buzzing go away when I'm not holding the wire in place with my hands?)

    As you can see, I know very little about electronics. Sorry for the long post, I tried to break it up by paragraph as best as I could to make it a little bit easier to get through. Thank you very much for all help in advance! :D

    EDIT: Another thought: Could there have possibly been another knob (such as a pickup selector) where that hole is now? Or not?
  2. lowerthetone

    lowerthetone

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    Hi there,

    The big hole on the front is probably caused by someone accidentely ripping out the input jack, wich is now installed on the back on the cover, wich is a very uncommon place for a input jack. It could be caused by someone standing on the instrument cable, creating a lot of force on the jack. The wood in that area is rather thin.

    The loose wire normally connects the bridge (and the strings) with the ground. This wire should stop the humming/buzzing from touching the strings. It must not be connected to the third lug of the tone pot. Just solder it to the metal casing of the tone put, just like the orange capacitor.

    So my advice would be; solder the loose wire to the back of the tonepot and see what happens.
  3. kohntarkosz

    kohntarkosz

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    I'm curious as to the role of the second, smaller, capacitor over the volume control.
  4. Chainsaw Willie

    Chainsaw Willie

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    Sometimes rolling off volume rolls off treble too much. You can put a tiny cap between the pickup hot and the pot wiper out to bleed some treble around the pot. That way as you lower volume the treble doesnt get attenuated as much.

    But then, sometimes you roll off the volume a bit to change the tone of the pickup, and this mod defeats that.
  5. Chainsaw Willie

    Chainsaw Willie

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    Yeah, someone just ripped the original output jack out of the wood and did a quick cheap "repair". The output jack out the back is just gunna get in the way. I woulda mad a new plate to go over the hole, like a mini pickguard, and installed the output jack in the original position.

    or maybe even buy a cheap output jack plate and install it over the ripped hole.

    maybe find a flat version of this:
    http://www.allparts.com/AP-0633-003-Black-Jackplate_p_370.html
  6. CGEffex

    CGEffex

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    Thanks for the replies, guys...for the loose wire, I'm gonna go ahead and solder the wire back onto the empty terminal, and go from there.

    As for the hole, I actually was originally planning on putting some kind of decorative (mini-pickguard) there to cover up the hole, and so now that I know the output jack would have been there, I'll adapt my plans and put the output jack back there where it belongs. (I had seen some pictures of similar guitars that had the input jack there where the hole is, and so I wondered if maybe it would have been there originally.)

    How would you recommend attaching this 'mini-pickguard' plate to the guitar? I'm visualizing the install right now, and at the top end of the plate a screw would go into that cavity in the guitar, and potentially mess with the electronics (Unless it was a certain length), and at the bottom end of the plate a screw would be going into the solid body of the guitar. (I'd like not to have to screw into the guitar body [although that seems the best way to go, one way or the other] and I really don't wanna use glue.) If there are any alternate less-destructive ideas I'll hear them out, but I guess seeing what damage has been done, it would be best to just put in the screws somehow and be done with it.

    About the guitar itself, does anyone know anything about this particular instrument? I have heard that Matsumoku-made guitars can be collectible (although I'm not positive yet if this is of that maker...help there would be appreciated as well!), and I don't want to chance (further) damaging the value of the instrument by putting more holes in it.

    Thanks for the help so far! :D

    EMERGENCY EDIT:
    Like a complete IDIOT, my stupid brain read lowerthetone's post something like '...the wire must be connected to the third lug of the tone pot...' :bawl: And, of course, I followed through... :crying:

    I feel like a total moron...(someone please tell me this mistake won't ruin anything :()

    Of course I'm going to de-solder the wire and fix this as soon as possible...I'll update again after I get through that...
  7. RBS_Johnson

    RBS_Johnson

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    It shouldn`t hurt anything, just solder it to the back of the pot and go on with playing.

    For all the bigger the hole in the bass is, I would consider putting a start style jack plate into it. Give me a second and I will dig up a picture for you.

    EDIT:
    Here is the jack plate: Clicky!
    Also check out what the plate looks like in it`s original home: here
  8. Chainsaw Willie

    Chainsaw Willie

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    Hey, that is a cool idea, a Strat (spell check does funny things!) recessed output jack. That might cover the hole all by itself.

    Although looking at the position of the torn hole, it looks like it may be too close to the edge for a normal angle as mounted on a Stratocaster.
  9. CGEffex

    CGEffex

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    Believe it or don't, my first thought when I realized I'd need a new cover plate was 'Oooh...I could use one of those Strat recessed jack plates!'

    But after examining that type of setup, it seems that I would have to actually cut more out of the guitar to fit a recessed plate on there (the hole itself really isn't that big).

    So, now, I'm thinking of something simple like this: Chrome Football Jack Plate

    And as a bonus, once I finish this, I can always add 'Custom' to the end of my guitar's name (once I find *that* out!)

    - "Hey, what kind of bass is that?"
    - "Oh, this is my Mako Something-or-other Custom!"
    - "Ooooh, that's nice!"
  10. Chainsaw Willie

    Chainsaw Willie

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    I have been unhappy with the footbal plates in the past. They wobble side to side and then start pulling up their two mounting screws.

    Try one of the square 4-screw plates like on an explorer, and watch out for curved plates. many of these are made to be on the side of a curved body. Some, like for an explorer, are flat.
  11. Arial Bender

    Arial Bender Supporting Member

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    Strat plate inside out.
  12. CGEffex

    CGEffex

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    Well, I got that grounding wire back off the third terminal, and I haven't soldered it back yet, but I have a *new* problem...

    That blue cable (with it's own wire and a smaller white cable inside) that connects to the top of the tone pot has come undone. The white cable that connects to the second terminal on the tone pot is still intact, but the blue cable's wire is undone, and there is not much wire left outside the end of the blue cable to solder back. So here's my question: I'm gonna try to carefully strip some of the blue away so I can get enough of an end to work with and solder back. However, am I correct in assuming that the wire inside the blue cable is not to touch the wire inside the smaller white cable that runs alongside it?

    *Also*...I did manage to test some positions for that grounding wire before the blue cable came loose (I don't want to solder this cable anymore until I'm sure where it goes):

    With the grounding wire on top of the tone pot (I tested this setup by holding it in place), there is still noise and buzzing, although just a little bit less.

    The only place the grounding wire *seems* to do any bit of good is touching that thin, shiny, metallic layer on the inside of that back plate (that the jack now goes through). This almost completely eliminates all the noise, although there still is a tiny bit left that goes away when I touch the volume control.

    Could it have been that the grounding wire (Which is quite stiff) was designed to simply push against that metallic layer? (I don't see how this is a very solid grounding method, but who knows?)

    I'm seriously looking into the origins of this instrument right now, maybe I can get my hands on some wiring diagrams or something...I'll post any info I find out.
  13. Chainsaw Willie

    Chainsaw Willie

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    The blue wire is coax. There is a center wire, and a braided tubular outer shield wire. The center wire is the signal hot side. The outer wire is the low side, or signal return, or ground, or shield... They should not be connected.

    It doesn't matter what order the pickup return, the pot cans, the bridge, and the outer ring of the output jack, are connected. All these things need to connect to the outer ring. The way they are daisy chained, any one break can kill the path for other things. That is probably why the bridge wire kills noise when hooked up to one spot and not the other. All grounds/shields have to be hooked up at the same time.


    Coax wire can be tricky to work. You can probably just let it be broken and add your own new wire attaching all the return points.
  14. Chainsaw Willie

    Chainsaw Willie

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    Basic P-bass wiring diagram.

    http://millerguitar.com/?a=pbass_style

    It simply doesn't matter how or where all these returns/grounds/shields tie together, but ALL of them MUST be tied together somehow.
  15. CGEffex

    CGEffex

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    Thank you for your help so far willie, but the middle paragraph of the former of your last two posts kinda went a few inches over my head (Although I think I have a decent handle on what you're getting at)

    I just drew myself a reference diagram of the electronics as they are in my guitar, and there seems to be a problem.

    In your diagram, a wire travels from the output jack to the top of the tone pot. In my guitar, this same wire travels from the output jack to the top of the volume pot, but the other wire still travels from the output jack tip to the middle terminal of the volume pot.

    Also, in your diagram it appears that that grounding wire should be connected to the top of the volume pot (Oddly enough, I believe that when I test-connected the grounding wire to the top of the volume pot in my guitar, the noise did stop!)

    Here's the diagram of the electronics in my guitar as they currently stand (Except that that one blue wire is not connected back to the top of the tone pot yet):
    [​IMG]
    I color coded the wires in my image as they appear in my guitar except for two differences: The wires inside the blue wires (The white wires) are color coded black in the image above (Because otherwise they wouldn't show up on the white bg!) and the white wires are also not show stuffed inside the blue wires as they are in my guitar. (Do I understand correctly that the white wires don't *really*need to be inside those blue wires, as long as they are connected properly? Also, why in my guitar is the blue wire coming from the pickups hooked up as the hot? Shouldn't that wire be red or something?
    Maybe this will help you help me 'debug' my guitar.
  16. Chainsaw Willie

    Chainsaw Willie

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    All these things we call return, low, ground, sheild...
    The pickup return side
    That lug on the volume pot
    The tone capacitor
    The bridge wire
    The volume pot can
    The tone pot can
    Any shielding

    They must somehow connect to the outer ring of the output jack. It doesn't matter how you do it.

    You could run 7 separate wires to each item and then tie them together at the jack.

    You could have one long wire that goes from the pickup to the pot lug to the pot can to the other pot can to the tone pot to the bridge wire to the output jack.

    It doesn't matter if your bridge wire goes to the volume pot can or the tone pot can.

    It just has to connect to the output jack or connect to something else that is connected to the output jack.

    If the bridge can be wired to either pot can, as long as that pot can is wired to the output jack.

    If it works well (eliminates hum) on one pot and not the other, it is because one pot can is not "grounded" to the output jack. A broken coax outer sheild wire would do that.
  17. CGEffex

    CGEffex

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    Thanks Willie, I think I finally have a handle on this whole thing. I also think I found out why I seemed to have buzzing for no apparent reason...even when I think I've got all the wiring right...

    It seems that one of the computers I use to amplify the guitar (it's a laptop, not a desktop like the other computer) has grounding issues itself.

    By rigging the guitar up to my audio recorder and using that as a direct, compact, secure method of amplifying the guitar, I get no noise whatsoever with the wires held in the places you told me to put them. Tomorrow I'm going to solder everything in its (hopefully) final place, so I'll let you know how that goes...

    Thanks for all the help, and thanks for putting up with all my newbie-ness in this field! I feel that I've learned quite a bit, and to me, that's the important part of any endeavor.

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