Bare Knuckle Pickups Forum
Forum Ringside => Tech => Topic started by: itamar101 on April 05, 2012, 11:21:01 PM
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I recently got my tech to installed a Gibson P94T Bridge pickup in my les paul studio and i quite like it but there is a big problem. Since then there's been loads of hum from both pickups (Humbucker and P90) and i cant stand anymore especially because i play with high gain and gain only makes it worse.
Anyway there is a crazy amount of hum and its making me mad, after taking it back to get fixed he only made it worse and after taking it back again it was back to where it was before he made it EVEN worse, so still loads of hum. The hum goes away when I touch the pickups or the input jack so the obvious assumption would be that it isn't grounded properly but after taking it back 3 times and him saying that he doesn't know what the problem is then there might be something else to it. I've opened it up and taken a look and and all of the connections seem strong but TBH I'm no expert with electronics so i need help.
Please take a look at the pics and tell me whats wrong. I plan on buying BKPs very soon but there is no point buying something as good as BKPs for a guitar that i hate playing because of a stupid amount of hum.
I have an SSS strat and there is almost no hum from that apart from the natural single coil hum and in the 2 & 4 positions there is ABSOLUTELY NO HUM AT ALL. So the problem is with the guitar.
Man, techs can be idiots sometimes.
Anyway, i'll upload some pics of the wiring.
Thanks in advance for any help.
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[PICS CONTINUED]
As far as i can tell for some reason everything seems to be connected to one volume pot and nothing is connected to any other pots, tone or volume, yet all of the control still function properly.
There's just a big mess on one pot and the rest of them have solder on them but nothing connected.
In fact, i'll just let you guys take a look and troubleshoot the problem.
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The guitar clearly isn't grounded properly. I usually ask if people have a multimeter handy, check that there is (almost) no resistance between the backs of the pots and the sleeve connection of the socket.
If you don't have a multimeter ... buy one! Although you could maybe try tracing the ground problem by temporarily holding short wires inside to connect all the backs of the pots to the socket sleeve tag. Growing another pair of hands may help here. Finding a competent guitar tech may help even more.
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Was there ever anything soldered to the back of the pots?
I wonder because there is solder clearly there
Gibson are using a printed circuit board with all the tracks already on there (I am not a fan of this arrangement!)
The backs of the pots should also be earthed or at least some part of the pot chassis - Gibson may be relying upon contact with the circuit board - often this is not enough.
Did it hum before the tech did the swap?
If not then maybe he has disturbed something when taking stuff out.
If it were my guitar I would probably choose to get rid of the PCB and just use loose components properly wired up
I;'d use the BKP 550k ohm pots and Jensen caps , and I would screen the cavities too is they were unscreened (I use a special nickel screening paint and it is brilliant)
If my workshop is near you you would always be welcome to bring the guitar in and I'd happily diagnose what ails it.
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TBH i never actually opened up the back before i realised the hum (which was after I changed the pickup) so I have no idea how it was wired.
But there was no hum before the pickups swap.
I hope to take the guitar to another tech in the near future because my local tech has obviously done a shite job.
I'm a bit tight on money right now so i'd rather not swap out all of the components to be honest :/
Of course, any more help is welcome :)
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Has he put one of the plugs on backwards and effectively made an earth wire a live wire - so some metal surface is acting as an antenna for noise
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I'd say your bridge isn't grounded or has a high resistance to ground. That little green box looks like it has the bridge ground wire running to it and that it wasn't soldered half way along the wire originally. Looks like a solderless connection. I'm pointing my blame at it right now especially if you can't actually get that wire out of there. If it was abused before the wire got cut, there may be damage underneath/inside.
And take that tape off please. Feline's theory might be happening in one of those.
Here's a before picture:
(http://farm4.static.flickr.com/3583/3464747842_d8fe453e85.jpg)
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Ok, I'll take the tape of later and upload a photo.
It's pretty crazy how some techs demand Payment to $%&# up your guitar :/
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Ok, I'll take the tape of later and upload a photo.
It's pretty crazy how some techs demand Payment to $%&# up your guitar :/
That is why seeking out a tech with a good reputation is important.
I pride myself on both high standards of work AND good customer service, and instil this in any techs that I train.
It sounds like the earth path has been messed up somehow.
I absolutely hate all these solder-less systems as they are so prone to failure, and to someone who knows how to solder the solderless systems are way more complicated than they need to be.
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Oh, the Gibson system is solder less?
So could I attempt to fix it myself (my solder iron is broken and it's a 1 1/2 hour drive to the nearest DIY store cos I live in a small town)?
How do you go about cinjecting everything with these solder less systems?
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Oh, the Gibson system is solder less?
So could I attempt to fix it myself (my solder iron is broken and it's a 1 1/2 hour drive to the nearest DIY store cos I live in a small town)?
How do you go about cinjecting everything with these solder less systems?
It's not exactly solderless, just all the components are mounted on a PCB which can make it harder to trace a fault. Where are you based? Maybe a helpful BKP forum member near you could assist - or at least recommend a competent repairer.
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Has he put one of the plugs on backwards and effectively made an earth wire a live wire - so some metal surface is acting as an antenna for noise
From the photos it looks likt the PCB connectors must be "keyed" so they only attach one way. Although I suppose a really cack-handed tech could manage to force them on the other way round but wouldn't he end up with an out of phase pickup?
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I'm in Israel. I doubt that there's anyone on this forums who could help me.
The pickups certainly aren't out of phase. They sound completely normal and they don't have any volume issues either (although the first time I tool it to the tech and he made it worse I couldn't any volume from the bridge pickups anymore there was EVEN more noise, he's fixed that though).
There's a bigger store about 30 minutes away and the guy there really seems to know what he's talking about. I think I'll him out. If not then I'll probably be visiting England in a few months and there's a store that I see doing set ups and changing pickups all the time but they don't sell gibsons so I'm not sure whether they'll know how to use the PCBs.
In that case, is there anybody in this forum nearby Cambridge who could give me a hand? London is probably also ok.
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I'm in Israel. I doubt that there's anyone on this forums who could help me.
The pickups certainly aren't out of phase. They sound completely normal and they don't have any volume issues either (although the first time I tool it to the tech and he made it worse I couldn't any volume from the bridge pickups anymore there was EVEN more noise, he's fixed that though).
There's a bigger store about 30 minutes away and the guy there really seems to know what he's talking about. I think I'll him out. If not then I'll probably be visiting England in a few months and there's a store that I see doing set ups and changing pickups all the time but they don't sell gibsons so I'm not sure whether they'll know how to use the PCBs.
In that case, is there anybody in this forum nearby Cambridge who could give me a hand? London is probably also ok.
I believe there are quite a few members in or around cambridge on this forum that would be able to help you.
Also im pretty sure anyone that knows that they are doing would be able to figure out that pcb system
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Thanks. I'll be posting pics of it without the tape shortly.
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I've not felt the need to look inside the wiring cavity on my new lp trad. is it going to have one of those type of circuit boards inside? How do people go about changing the pups? Do you all cut the plugs off the ends of the pup leads?
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I've not felt the need to look inside the wiring cavity on my new lp trad. is it going to have one of those type of circuit boards inside? How do people go about changing the pups? Do you all cut the plugs off the ends of the pup leads?
I did in the first instance - messy, but works :D.
But then I wanted to change caps a few weeks/months later... that was beyond me... so I threw out the board and replaced it all with traditional stuff. I felt a bit more secure with the guitar once I'd done that, but that was probably my imagination.
For purely practical purposes, if you only want to change pups, I'd say the cutting the plugs and attaching them to the new pups is fine.
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Any idea if you can buy the plugs anywhere?
This would be a great selling point for Tims products if he could give the option to provide pickups with these plugs fitted. You might give people who are scared of soldering irons/warranty voiding, the peace of mind to jump in and change stock pups. It might even add resale value to the stock pups. I'll send him a pm.
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I believe they are standard plugs, but I could't figure out which ones you'd need (and I didn't fancy acquiring the tool for wiring them at the time, anyway).
I'm sure I've seen a post on here somewhere from someone who could identify the plugs and even posted a link - but I can't find it (didn't look too hard though, I'm at work!)
Whether BKP want to provide it as an option though... could be fraught with difficulties, even for the people it might help (there's the "how long do you want the pickup cable to be?" question for starters)
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I've not felt the need to look inside the wiring cavity on my new lp trad. is it going to have one of those type of circuit boards inside?
I'd like to think that in a Traditional they'd stick to old-fashioned wiring. But with Gibson, anything is possible....
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Any idea if you can buy the plugs anywhere?
This would be a great selling point for Tims products if he could give the option to provide pickups with these plugs fitted. You might give people who are scared of soldering irons/warranty voiding, the peace of mind to jump in and change stock pups. It might even add resale value to the stock pups. I'll send him a pm.
The connectors will be fairly readily available, and at a reasonable cost too-- the issue comes with the crimp tool that is required to crimp the pins onto each of the wires. Often these crimp tools often cost £100s just for the hand tool to crimp the connection properly! Obviously you can bodge it with a pair of needle-nosed pliers, but it isn't as good/reliable/professional :(
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The connectors will be fairly readily available, and at a reasonable cost too-- the issue comes with the crimp tool that is required to crimp the pins onto each of the wires. Often these crimp tools often cost £100s just for the hand tool to crimp the connection properly! Obviously you can bodge it with a pair of needle-nosed pliers, but it isn't as good/reliable/professional :(
the crimpers will not cost any more than £50 tops. we have a set at work anyway.