Semi-hollow Rewiring

Discussion in 'Restoration & Repair' started by basskidd, Sep 24, 2015.

  1. basskidd

    basskidd New Member

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    Howdy, new guy on the boards here.
    Sorry if this has been posted already, I used the search function but wasn't able to find anything.
    I'm working on repairing the wiring on a Hezz semi-hollow, and have run into a small issue. I have the pots sunk into the body (still accessible with floss, crude but effective) but am still unable to properly access the pots themselves. The first issue is that the components wired between the pots don't allow for the necessary maneuverability, but the main issue is that the f-holes themselves are too small to pull the entire wired array out of the cavity. I've attached a few pictures to illustrate the issue.
    I was wondering if anyone else has come across this, and if so (or if not) have any recommendations as to how to access the electronics?

    Thanks!
     

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  2. Duplex Dave

    Duplex Dave Active Member

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    You probably need to pull everything in and out through one of the pickup holes. What are you trying to repair with the wiring?
     
  3. fumblefinger

    fumblefinger Member

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    Note to self: Never buy a hollow body needing electrical work....
     
  4. basskidd

    basskidd New Member

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    I was afraid you were going to say that.. haha
    There are a couple things a little screwy, first off the ground sounds like it's been broken. Other than that I'm having a hard time diagnosing whether the issue is dirty pots or an intermittent connection somewhere in the circuit
     
  5. pshupe

    pshupe Member

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    Can you post a pic of the whole guitar? I've never heard of Hezz. Generally I think the f-holes are where all the wires and pots were fed back in after wiring. I have heard of people using medical tubing attached to the pot shafts for pulling them up through the holes. Those f-holes do look quite thin, unlike a ES-335

    Cheers Peter.
     
  6. Duplex Dave

    Duplex Dave Active Member

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    Okay, some of the older off brands never had a ground wire installed. If it has a Tun-o-matic style bridge it should be in one of the anchor/post holes. If it has a trapeze style tailpiece like an ES-125 it will be under the mounting plate at the tail end of the guitar.
    If you have dirty pots and no string ground (2 problems or more) then it would serve your time to re-wire the whole system instead of applying a band-aid. You could target your 2 problems then get it all back together and the switch goes bad, then you're starting over. Also, those really old pots can sometimes disintegrate inside when sprayed with De-Oxit (electronics cleaner for guitars).
    Hope that helps.
     
  7. basskidd

    basskidd New Member

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    Sure thing! Here are a couple photos.
    There is an inscription on the inner belly of the guitar (visible through the f-hole) that says
    "Sept 1973 Made by Hezz Hall"
    if anyone is interested.
    Sorry about the late reply, been a crazy busy week haha
     

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  8. basskidd

    basskidd New Member

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    Yeah, this one has the turn-o-matic bridge, the ground wire is run between the neck pup pot and the anchor hole on the bridge. Still getting the crazy ground hum issue, it goes away completely when I touch metal on the guitar haha.. Pots are in good working order again though, and I'd honestly rather avoid a complete overhaul of the electronics because I feel that it may be a little ways out of my league haha
    Any thoughts on fixing the ground? All the connections are solid and I can't seem to figure out what's wrong with it..
     
  9. Luthier-Atlanta

    Luthier-Atlanta New Member

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    I run fishing line thru the holes, one for each item. Tye the line to each one and pull the furthest one thru first. Tye the line to the shaft.
     
  10. basskidd

    basskidd New Member

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    I did the same thing with floss haha
    trying to get this crazy ground problem worked out now :p
     
  11. Duplex Dave

    Duplex Dave Active Member

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    If the hum goes away when you touch any metal part on the guitar (most importantly the strings) then the ground is installed correctly. Does the hum get a little less when both pickups are on by chance? I'm thinking those are single coil pickups like P-90's and the hum (60 cycle hum inherent to single coils) will be present just like any single coil guitar. If you remove (carefully) one of the pickups you will see either 1 or 2 coil construction.
    That looks like a really, really cool guitar! If it feels like you're getting in over your head just take it in to the best local luthier you can find, and maybe try to establish a value on the instrument before you go any further.
     
  12. Luthier-Atlanta

    Luthier-Atlanta New Member

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    Did you run a ground wire out of the tail strap/piece screw hole?
     
    Last edited: Oct 5, 2015
  13. basskidd

    basskidd New Member

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    I'm not sure, can't get a good look that far back. The ground that is in place runs between the bridge anchor hold and the neck pickup volume pot
     
  14. basskidd

    basskidd New Member

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    No, actually the hum gets louder with both pups on haha
    I'm pretty sure they're single coil, but there's a fibrous cover over the back plating.
    I would really like to get rid of the hum, it's causing distortion and a bit of signal loss when I'm not touching metal (i.e. Anytime I take my hands off the guitar)
     
  15. Duplex Dave

    Duplex Dave Active Member

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    You're not going to be able to escape the hum with a single coil set-up. However, it can be sometimes be minimized. These pickups look as old as the guitar and they may never sound any better than they do now. But, you could try to have them re-potted. It's a process of removing the covers and dunking them in liquid wax. It can improve squeeling and microphonic problems with pickups. But it won't change the fact that you are dealing with single coils. It is odd that it gets louder with both on, they should become a little hum canceling like the 2 and 4 positions on a Strat switch.
     
  16. basskidd

    basskidd New Member

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    I get that single coils invariable have a bit of hum to them, the problem is rather that it sounds like this:

    https://drive.google.com/file/d/0Bz_rFvQwkCgKTUczYUNSejFxNDA/view?usp=sharing

    (just a quick recording I did while getting ready for work)
    The cutting in and out you hear at the beginning is just from me placing my finger on the trem system, while I'm fretting the sound is quite good but the open string toward the end gets a little weird..
    I figured it'd be easier to show rather that try to describe the issue haha
     
  17. basskidd

    basskidd New Member

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    Any thoughts on what could be causing this?
     
  18. Duplex Dave

    Duplex Dave Active Member

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    It doesn't sound like a ground issue, it sounds mechanical. It sounds like the pickup is physically rattling as the note decays. I would make sure it is mounted good and solid. It could also be loose wraps in the coil of the pickup. Again, I'm not a electric guitar guru but this does not sound like a ground related issue.
    Very nice recording you made for the demo!
     
  19. basskidd

    basskidd New Member

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    Haha thanks, was just di into logic, nothing fancy :)

    I think I've tracked down the source of the problem, it seems the pickup selector is the culprit. Essentially the three wires going from the selector to the pickups are causing trouble. When I touch the wires (at the soldering point or on the plastic casing) before the solder point (still on the side of the selector switch) the humming gets louder. There's no change in noise when I touch the housing after the solder point (closer to the pots). You can see in the picture that only one wire (the red one) appears to be of the shielded variety. Needless to say I'm at a complete loss here. Could it be a mechanical issue with the selector switch? And if so would replacing it do the trick?
     

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  20. Duplex Dave

    Duplex Dave Active Member

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    Oh. Those solder joints don't look so good and they need to be sleeved with heat shrink. A combination of a cold or loose solder joint and if any of the connections are touching one another or any other metal part inside you're going to have problems. I would start with that. Get some heat shrink from HD or Radio Shack, cut and re-solder those leads.
     

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