Humbucker - what are the 4 little screws on the bottom for?

[SGJ]

I was trying to figure out what kind of humbuckers I have in my SG, so I carefully lifted the bridge pickup out of the body and removed the 4 little screws on the bottom (thinking this is how you take the cover off), the cover didn't come off so I put the 4 little screws back in, put the pickup back in and now the bridge pickup doesnt' work. The other strange thing is that now both volume knobs control the neck pickup volume? Any ideas as to what I did here?

[Dynadude]

Sounds like you may have pinch grounded a lead inside the pickup.

 

I'd take the cover off and check it out. You need to break the two big solder joints to take the cover off. They are on the bottom of the pickup at the top and bottom edges.

 

Be carefull not to overheat the pickup base, or you will short the pickup, then it's time for a rewind.

[80LPC]

If you didn't know what the 4 screws were for, I don't think you should be doing anything else to the pickup. It might be best to let a tech check it over before it gets too expensive.

[Murph]

1 is an M.

1 is a J.

Two of them are O's.

 

I'm hoping you didn't let the MOJO out.........

 

KIDDING........

 

Murph.

[lpdeluxe]

If you didn't know what the 4 screws were for' date=' I don't think you should be doing anything else to the pickup. It might be best to let a tech check it over before it gets too expensive. [/quote']

 

+1. Next you'll be asking us how to install new pickups, and what do the knobs attach to. Quit while you're ahead.

 

Get a copy of Dan Erlewine's Guitar Repair book. There are also several books out there specifically on electric guitars and pickups in particular.

 

Or do what a lot of us did, back in the day before the internet: buy a hammered cheapo and dig into it. I hate to think of all the indignities I visited upon a succession of Teiscos, Venturas and whatnot while I was educating myself.

[Murph]

Dixon's?

 

Yea, lpdeluxe, ya wonder how we survived without the internet......................

 

Best to ya.

 

Murph.

[SGJ]

I realize I messed up and shouldn't have taken the screws out, I don't plan on trying to fix it myself, I was just wondering what exactly happened and why would both volume knobs control the neck pickup now? I'll take the guitar in to get looked at. Would it be cheaper to buy a new pickup and have someone install it, or try to get it fixed? Is the pickup likely beyond repair?

[Dynadude]

I realize I messed up and shouldn't have taken the screws out' date=' I don't plan on trying to fix it myself, I was just wondering what exactly happened and why would both volume knobs control the neck pickup now? I'll take the guitar in to get looked at. Would it be cheaper to buy a new pickup and have someone install it, or try to get it fixed? Is the pickup likely beyond repair? [/quote']

 

If you just pinch grounded a lead it should be an inexpensive repair. I doubt that the pickup is ruined.

[80LPC]

SGJ, did you de-solder the pickup to remove it from the body ? When moving wires, the outer braid of the pickup wire can touch other components. Have you done anything at all within the control cavity ?

[SGJ]

SGJ' date=' did you de-solder the pickup to remove it from the body ? When moving wires, the outer braid of the pickup wire can touch other components. Have you done anything at all within the control cavity ? [/quote']

 

I did no soldering or de-soldering. There wasn't much excess wire, so all I could do was tilt the pickup up so I could see the bottom. I was trying to determine what kind of pickups they were. I saw the Gibson logo on the bottom and also saw the 4 screws. Thats when curiosity got the best of me. I took the screws out, realized that was a dumb thing to do, put them back in, then tilted the pickup back down into the body and screwed it back in.

 

I'm really not 100% useless with this kind of stuff, I just didn't know what those screws were for. If its a simple fix I"d consider trying it. Worst case scenario I need to buy a new pickup. Its not the original pickup anyway. The guitar is 25 years old and has had mods to it before. An extra little switch was added at some point, but its not hooked up to anything currently. I could have a coil tap or something added if I had the right pickup.

[Dynadude]

I'd check inside the control cavity to make sure the wire shield hasn't grounded another circuit. If it has not, then you will need to get the cover off of the pickup to find the damage. (pinch probably).

 

You'll need a GOOD soldering gun and a solder wick. A piece of braided picture hanging wire will work as a wick. You'll need it to pull the solder away from the cover once it's melted. Use some flux paste on the wick, and heat it along with the solder in the crack.

 

Once you get the cover off, be very careful not to damage the fine wire leads that connect the coils to the lead wire. You will probably find a place where the lead has gotten between the base and the coils. Simply loosen the four screws again, get the wire out from under, and re tighten the screws. You will also want to be sure that the pinched spot in the lead is insulated with a piece of good tape before closing it all up again.

 

I'd be more comfortable doing this kind of repair with the pickup out of the guitar. Lacquer hates heat.

 

With the pickup cut loose from the controls, you can check the ohm resistance on the pickup. That would get you closer to finding the fault without opening the pickup, which can be a bit of work. Those solder joints are tough to free up sometimes.

 

You can also check the other tone/volume set with the bad? pickup out of the circuit. That should also help pinpoint the fault.

[80LPC]

Removing a pickup cover is not to be undertaken lightly. A good quality soldering iron is needed, but preferably around 80 watts, and temperature controlled. The idea is to get the solder melted in the shortest time, otherwise heat is transferred to the magnet and bobbins. Magnets do not like heat, and neither does plastic ! The shape of the soldering iron tip is critical - a fine tip for detail work will transfer heat much slower than a flat or oval tip. Some people heat up the solder, then tap the pickup to shake off the molten solder. Magnets can be weakened by shock, and it won't do the coils any good either, so I personally wouldn't do this. A solder sucker is good, and quick. Remember, we want to get the solder melted quickly, then remove the heat quickly. You can heat the solder, then slide a thin knife into the gap if you wanted. Wiggle the knife as the solder cools.

Don't be tempted to use a soldering gun ! These generate magnetic fields that will permanently affect your magnet. Be aware that your pickup might have been wax potted. You might have broken the solder joint, but now you need to warm up the cover with a hair drier to melt this wax.

The cover might have been potted with silicone which has a very strong bond.

On the face of it, removing a cover seems straightforward, but there are so many ways it can go wrong.

[SGJ]

Its too bad pickup covers look so cool, they seem to be a major pain in the ***. I don't have a good soldering iron so I'll just have to take the guitar in and bite the bullet.

 

Here's a picture of the back. I'm not sure what that extra switch was used for. Its not hooked up to anything. If I could have a pickup with a coil tap hooked up to that switch I might just replace the pickup I wrecked. Maybe I could hook the switch up to a fake pickup that opens up and starts on fire, like Ace Frehley!

 

[80LPC]

I turned your picture the right way up. It's been wired so that your volume controls are at the top. The strange thing is that your output from the switch does not go directly to the output socket. It goes down to the (former) bridge volume pot, so you have an extra volume control. This connects to the remaining pot for a master tone control. Scroll down to check this Gibson wiring diagram for how it should be. http://www.1728.com/guitar.htm

The mini switch can be used to coil split both pickups.

You have the strong, side mounted socket - what year is this guitar ?

[SGJ]

I turned your picture the right way up. It's been wired so that your volume controls are at the top. The strange thing is that your output from the switch does not go directly to the output socket. It goes down to the (former) bridge volume pot' date=' so you have an extra volume control. This connects to the remaining pot for a master tone control. Scroll down to check this Gibson wiring diagram for how it should be. http://www.1728.com/guitar.htm

The mini switch can be used to coil split both pickups.

You have the strong, side mounted socket - what year is this guitar ?[/quote']

 

Its a 1982. I bought it sight unseen on a bit of a whim. It plays really nice so I'd like to fix it up a bit. It looks like its had a fairly rough life but it has potential. The switch is a bit scratchy too, so I'm debating doing an overhaul on the electronics. I don't think much is original on this guitar anyway. It will need a refret soon too, so I'm also considering just selling it. I don't want to have to dump in a ton of money into it. I'd post a picture of it here but this forum doesn't seem to allow attachments. And I don't have it posted on any website and all file hosting sites are blocked from where I am (at work).