Changing humbuckers; questions from a novice

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MagicPigDetectiveMagicPigDetective Frets: 2992
edited March 2018 in Making & Modding

I plan to change the humbuckers on my 1993 Washburn Mercury MG42. I’ve never touched a guitars wiring in 25 years, so it’s about time I learnt, 

The 2 stock humbuckers, no idea what they are, have three height adjusting screws; most pickups seem to have only two. There are three holes in the scratchplate, if I use a two screw humbucker it will need a new central hole on one side. Is the answer as simple as just drilling a new hole in the scratchplate, a straightforward job with a power drill? What kind of bit would be best? 

Pots: I’m looking at Iron Gear pickups and they recommend 500k pots and 0.22 tone capacitors. The volume pot on the MG-42 is marked 250k;  not sure what the tone pot is. The tone capacitor is green, no idea if its a 0.22. The tone pot is a push pull to split the bridge pickup. 

So do I need to replace the pots and maybe a capacitor? I’m a total novice with guitar wiring but want to give it a go. Below are some photos if the innards; in what kind of state does it look? It was made in Korea. Perhaps I should change the 3 way blade while I’m at it? Anything else to note? 

https://i.imgur.com/D4lQ68C.jpg

https://i.imgur.com/995soUu.jpg

https://i.imgur.com/erRUMx7.jpg

https://i.imgur.com/hAtHy0v.jpg

https://i.imgur.com/zPxoDq6.jpg

https://i.imgur.com/TyO5v8B.jpg


Any advice would be much appreciated. 











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Comments

  • sawyersawyer Frets: 732
    Fender quite often use 3 screw humbuckers. Checkout Telecaster Deluxes.Maybe they could be an option?
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  • ICBMICBM Frets: 71951
    It’s probably worth asking... what is it you don’t like about the ones it has? I would be inclined not to drill holes if it’s not really necessary.

    The stock controls are junk though, and do definitely need replacing - including the jack, which is bound to be as well - probably except for the tone pot and cap, which are OK.

    If it matters, the 250K volume pot value may be chosen because the bridge pickup has a coil split, and a single coil usually sounds worse with a 500K pot than a humbucker does with a 250, but there is a better way to fix this problem if only one pickup is being split with the switch.

    Replacing the 250K volume pot with a good quality 500K should open the tone up noticeably.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • FunkfingersFunkfingers Frets: 14320
    edited March 2018
    MagicPigDetective said:
    2 stock humbuckers, no idea what they are
    https://tenor.com/view/poo-emoji-gif-8722140
    ICBM said:
    The stock controls ... definitely need replacing ... except for the tone pot and cap, which are OK.
    +1

    I would remove the entire pickup and electronics assembly from the scratchplate without desoldering anything except the bridge grounding wire and both terminals on the output jack socket. Start from scratch with clean, good quality components.

    ICBM said:
    I would be inclined not to drill holes if it’s not really necessary.
    The spacing of the two screws fastening that seven contact selector switch may not comply to the standard distance found on the overwhelming majority of switch designs. Some drilling or light filing may be unavoidable. 

    How deep is the control cavity? Would it accommodate a Superswitch? The guitar has four pickup coils. You might as well get more than three sounds out of them.
    Be seeing you.
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  • ICBM said:
    It’s probably worth asking... what is it you don’t like about the ones it has? I would be inclined not to drill holes if it’s not really necessary.

    Good question. The guitar is not worth much, but the bridge has now been upgraded and I'm using it as a modding platform as a way to teach myself about the inner workings of a guitar and get my soldering skills up to scratch. I've already learnt more about the wiring in the last 24 hours than in my entire life!! The pickups themselves sound ok but nothing special, and after 25 years with it it's time for a change. I would not be too bothered about two empty holes above each pick up, to be honest.

    MagicPigDetective said:
    2 stock humbuckers, no idea what they are
    https://tenor.com/view/poo-emoji-gif-8722140

    Thanks for the confirmation :lol:

    Looked again; the treble pot capacitor is 0.22 and the tone pot is 500k. The output jack does look junk. The control cavity is 40mm deep. Superswitch - so that would give you 5 sounds, out of the various combinations of the 4 singe coils? sounds good but daunting for a first time project. In terms of removing the electrics, would it be then a case of removing the pots and switches, keeping the wires and resoldering them to the new pots/switch? Or would new wires be better? Sorry it I'm asking the obvious. There's a lot more to this than I imagined!  

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  • FunkfingersFunkfingers Frets: 14320
    Does the tone pot produce crackling sounds as you rotate the control knob from ten to zero and back? If not, follow ICBM's suggestion to retain it.

    I notice that the bridge position pickup appears to have chunky three-conductor + shield output cable whereas the neck position pickup has a thinner single-con + shield type. This suggests that the bridge position humbucker has sufficiently high output to be worth coil splitting.

    If you have a meter, take D.C. resistance readings of the two pickups. They might be worth persevering with.
    Be seeing you.
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  • ICBMICBM Frets: 71951
    Funkfingers said:
    The spacing of the two screws fastening that seven contact selector switch may not comply to the standard distance found on the overwhelming majority of switch designs. Some drilling or light filing may be unavoidable.
    I think that one is standard - the 'short frame' switches don't have the extra lip at each end. I am unfortunately quite familiar with this problem since I'm quite a fan of Matsumoku guitars which often use short-frame switches...

    (If it isn't standard, I have a few better-quality short-frame switches available, but only 3-way.)

    MagicPigDetective said:

    The guitar is not worth much, but the bridge has now been upgraded and I'm using it as a modding platform as a way to teach myself about the inner workings of a guitar and get my soldering skills up to scratch. I've already learnt more about the wiring in the last 24 hours than in my entire life!! The pickups themselves sound ok but nothing special, and after 25 years with it it's time for a change. I would not be too bothered about two empty holes above each pick up, to be honest.
    It certainly isn't a valuable guitar, and a couple of extra holes won't really devalue it an any way - but actually, the three-screw pickups are better because you can properly adjust the angle relative to the strings, rather than having them just flop around. You often find you need to put bits of foam rubber under 2-screw pickups to get them right...

    Does the tone pot produce crackling sounds as you rotate the control knob from ten to zero and back? If not, follow ICBM's suggestion to retain it.
    Even if it does, try cleaning it first - it's a mini-pot, but most push-pulls are based on these anyway and it's not actually that bad. The volume pot is worse quality.

    I notice that the bridge position pickup appears to have chunky three-conductor + shield output cable whereas the neck position pickup has a thinner single-con + shield type. This suggests that the bridge position humbucker has sufficiently high output to be worth coil splitting.
    The bridge pickup is definitely splittable on these, that's what the push-pull does.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Looking at this diagram, you could split two pickups with the current set up. Pulling the tone pot would split both? If the volume pot was also push pull, you could split both independently, right? 

    http://www.irongear.co.uk/2_x_humbuckers__1_vol__1_tone_switched___3-way_blade_v01_igwm.gif
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  • ICBMICBM Frets: 71951
    Looking at this diagram, you could split two pickups with the current set up. Pulling the tone pot would split both? If the volume pot was also push pull, you could split both independently, right? 
    Yes, exactly.

    Using independent switches not only means two more sounds (each full humbucker added to the other single coil), it means you can use the second half of the switch to add a resistor to give an effective 250K volume pot value when it's in single-coil mode.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • MagicPigDetectiveMagicPigDetective Frets: 2992
    edited March 2018

    ICBM said:
    Looking at this diagram, you could split two pickups with the current set up. Pulling the tone pot would split both? If the volume pot was also push pull, you could split both independently, right? 
    Yes, exactly.

    Using independent switches not only means two more sounds (each full humbucker added to the other single coil), it means you can use the second half of the switch to add a resistor to give an effective 250K volume pot value when it's in single-coil mode.
    Ok great, think that's the way I'll go.

    The current 3 way blade swicth has a gap of ~41mm between the two screw holes, the same a the gap on my strat, so I assume it's standard.

    I'm looking at the top switch in the link below:

    http://www.axetec.co.uk/guitar_parts_uk_049.htm.

    Are the parts on this website what you would class as good quality, or cheap and nasty? Which website is recommended for pots and switches?

    Aslo - I don't think the neck pickup is connected to the tone pot, it goes straight to the volume. I might need some wire. Is hook up wire suitable for all the connections? I take it the different colours are to help identify different wires and have no significance, apart from black for ground? 

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  • FunkfingersFunkfingers Frets: 14320
    Would you like your selector switch to last weeks or years? 

    IMO, all of the items illustrated on the Axetec page are cheap 'n' nasty. I avoid all eight-in-line contact switches on principle. Their "CRL-type" switch is better but still shows signs of Cheepnis. 

    The CRL-branded examples with a tension spring are the nicest to use. The unsprung CRL type sold by Fender is reliable but less satisfying to the touch.


    Be seeing you.
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  • I have much to learn. I’m ordering Dan Erlewine’s book and will retreat to youtube research and come back wiser. 
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