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Post by bladerunner on Sept 3, 2006 8:44:24 GMT -5
Hello All:
I got my hands on a vintage japanese styly (60"s 0r 70's) black beauty les paul.. ith
I'm a newbie with electronics but am very adaptable in learning so anything of help I will appreciatedd..
2 volume, 2 tone pots (500K with capacitors)
The problem with it is that there is no sound out of the neck pickup. There is a short I believe.
I changed out the 3 way switch and soldered it back to original wiring specs... Still no sound out of the neck pickup.
I bought an extra 500k pot and thought that this would be the problem.. I switch out the orginal volume pot with the new one to orginal wiring specs.. No sound out of the neck pickup.. I replaced back the original volume pot with original wiring specs and replace the accompanying tone pot with the extra new 500k pot and still problem..
I assume that 500k pots can be use either as a tone or volume pot..
I took another bridge pickup and wired it to the volume pot which is assigned to it and no sound...
So I'm baffled at what I should do next...
I recieved this guitar with no sound out of the neck pickup... as a note the two tone (original pots) have registers tied to them as well..
I either have a short somewhere which I need help with diagnosis or I recieved the guitar all wired incorrectly.. It looks like all original electronics, i.e wiring, pickups, pots...
Can someone PLEASE HELP ME. What's next to fix this issue? Anyone can give instructions, assistance with this?
The bridge pickup screams 60's style crunch and want to hear what the neck pickup sounds like..(very unique sound)
Here is a bit more info.
Bridge pickup (switch down) I get sound Middle pickup position,, I get sound (only bridge pickup sounds. not both.. sounds exactily as bridge pickup Neck pickup position...no sound at all..
does this sound like it's not wired right? where can I find some correct schematics diagrams or assistance...
thxs
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Post by sumgai on Sept 3, 2006 16:30:10 GMT -5
br, Hi, and to the forums! Well, you've certainly made my case for linear troubleshooting! You've jumped all over the map, and still haven't found the culprit, but that's to be expected. Here, try this: 1) With everything left stock (as it came to you), and both covers off the back, plug the guitar into your amp (which is turned on). 2) Place the selector switch in the middle position (both pickups), and set all 4 pots to 10 (all the way up). 3) Use your finger to touch each terminal of the selector switch. Move the switch to all three positions as you do this. At this point, I expect that you will get a fair amount of buzzing out of the amp when you touch the side for the bridge pickup. What we want to know right now is, do you get that same buzzing when you touch the neck side? 3) If there was no buzz, then the switch is bad. (But there might be a bad solder joint.) 4) If there was buzz, then touch the center terminal of the volume pot. If the buzz is gone, the volume control is suspect. Disconnect the center terminal wire, and touch it directly to the upper terminal (the one going to the switch). Re-test. Got buzz? The volume control is definitely bad. 5) If you still don't get any buzzing, then you need to investigate each remaining component in the signal path. Re-connect the wire to the pot's center terminal, then do this: 5a) Disconnect the tone control, and re-test. Got buzzing? The tone control is bad, or possibly it was miswired (it should look exactly like the bridge tone setup). Still no buzz...... 5b) Leaving the tone control disconnected, disconnect the bridge pickup, and re-test. Got buzzing? The pup is shorted. Still no buzz...... 5c) You've got a bad case of cold solder joints, or there is a damaged wire somewhere. Only visual inspection can find the former, and only a multimeter can find the latter. What I've done here is illustrate how to go from one end of the signal chain to the other, without jumping around and skipping over stuff. This may take longer to execute, but it's much less frustrating, and is guaranteed to find the crapped-out part. But along the way, be sure to closely inspect all solder joints, sometimes they can go bad, but look "OK" at a casual glance. For once, you're in the lucky seat, you don't have to disassemble your rig in order to do these tests. Strat owners will attest to the ugliness of trying this procedure on a top-loaded guitar. Ask me how I know. ;D HTH, and good luck! sumgai
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Post by ChrisK on Sept 3, 2006 17:19:39 GMT -5
Or, connect an Ohmmeter to the guitar's output jack (the input jack is on the amp ). GENERIC LP TROUBLE-SHOOTING PROCESS: Put all of the controls at "10" and measure the resistance in all three positions of the (three-way) toggle switch. Record your measurements. You should read about 5 to 10 (or more) k Ohms for the bridge and similar for the neck. In the middle position, you should read (neck Ohms * bridge Ohms)/(neck Ohms + bridge Ohms). If you read nearly 0 Ohms in the middle and neck position, you have a pickup-related short, go to step "AA". If you read around 500k Ohms or open or out of range in the neck position, you have an open, go to step "BB". Step "AA". Put the switch in the neck position. While monitoring the resistance thru the output jack, turn the neck volume pot down to about "8". If the pickup (or tone pot if wired directly across the pickup) is shorted, you should read about 125 k Ohms. If this does not occur, the problem is in the volume pot (or tone pot if wired directly across the pickups volume pot's output), or possibly the selector switch, or in the wiring. Step "BB" While the black lead on the meter is connected to the pickup cable's common wire, measure the resistance directly at the end of the pickups cable's output wire. If you read resistance as above (5 to 10 or more k Ohms), the problem is between the pickup and the output jack. If you read over-range or very high, you have an open pickup coil. (Of course, if you read nearly 0 Ohms with the pickup unsoldered, the pickup is shorted.) End GENERIC LP TROUBLE-SHOOTING PROCESS. (Or brain diagnosis thru the nose.) This clue indicates that you have an open in the neck pickup circuitry. If this guitar has normal LP wiring (virtually all do), with the pickup's outputs directly connected to the end terminals on the volume pots, measure the resistance at the output jack with the volume and tone pots at "10" and the neck selected. I suspect that you'll read about 500k Ohms Turn the neck volume down to "0". If all volume and switch circuitry are ok, the resistance should go down to nearly zero. If not, you may have an open in this circuitry. If so, you have an open pickup coil/wire (it's GeFooey) (or a bad volume pot input terminal). This can be fixed in a pickup sometimes, but surgery is involved. The tone pot may also have an open, but this will have no effect on this stage of troubleshooting and can be addressed later on. A simple test of the veracity of the neck pickup (and its circuitry) is to unsolder the bridge pickup and connect the neck pickup in its place. Solder the bridge pickup in the neck pickups place. Select the bridge pickup position, if you get no sound, the neck pickup is GeFooey. If you get sound; Select the neck pickup position, if you get no sound, the neck circuitry is GeFooey. We've given a lot of clues here. Q.E.D.
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Post by sumgai on Sept 3, 2006 20:25:34 GMT -5
Chris, Errrrr, that ain't quite so. Recall that what you've described is what we usually label as "forward" wiring, where the output to the amp comes off the center terminal (the wiper). However, in a Les Paul scenario, wiring like this will cause a total signal shut-off if either volume control is turned down to 0 (zero). For that reason, Gibson (and others) execute what we label as "reverse" wiring - the pickup's leads are hooked up to ground and the center terminal, and the remaining terminal is the one that goes to the output jack (with a short stop along the way at the pickup selector switch). bladerunner did say that his LP copy has been restored "back to original wiring specs", so we have to assume that he's using Gibson's standard "reverse" scheme, and therefore, your instructions to him would have been confusing. Just didn't want br to start tearing his hair out by the roots, trying to figure how he could have mis-wired his pride-and-joy, I'm sure you understand. sumgai
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Post by ChrisK on Sept 3, 2006 20:33:01 GMT -5
I know, but I was keying off of
Gibson may not have implemented the changes yet and the copy may have been faithful. I constantly see posts about that inquire about output shunting in LP's (and copies thereof) from the original wiring (volume pot wipers go to switch).
In the beginning, he should just measure each pickup's resistance across its output wires directly.
If ok, the problem is downstream. If the pickups pass the resistance testing, swapping their connections would verify downstream circuitry issues.
Deductive reasoning is.
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Post by bladerunner on Sept 3, 2006 21:12:56 GMT -5
Hello all. I will try the above and let your know.. In the meantime, here is my futile 5 hour attempt at this..
Here is a bit more info.
Bridge pickup (switch down) I get sound Middle pickup position,, I get sound (only bridge & neck pickup sounds. ..but sounds exactily as bridge pickup Neck pickup position...no sound at all..
does this sound like it's not wired right? I looked at the basic wiring schematics for les paul and I don't see any problems..
Ok..i''ve spent the last 5 hours trying to figure this out... I replaced the original affected (which I thought) with a new pot and wired like it was..Incidentally the bridge pickup wiring is the same as the neck (the one that is affected)...
this did not work.. I replaced the 3 way switch and still the neck pickup does not work.. I tried replacing the neck pickup with another one,,,I disconnect the positve wire off the pot but left the ground one on the original, then soldered on the other neck pickup.. same thing,,, I only get the middle and bridge positions working...
Incidentially with the middle pickup the bridge pots (volume and tone) only work...at the bridge pickup configuration, the bridge pots and tone work as well..
I bought from circuit city some .47 capacitors as both tone pots have .47 capacitor resistors on it as well I don't think that replacing teh .47 capictor on the neck-pickup tone pot will fix anthing..
as with the three way switch, I have the middle prong going to the input jack as it should...I don't think the ground wire coming off the input jack would affect the neck pickup? would it
incidentally these humbucker pickups only have one main wire shielded.i.e a gray and white wire coming out..white soldered onto the pot prongs and the gray on the back of the volume pots (grounded)
the basic les paul diagrams I have in place... so what next? this is really frustrating...
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Post by ChrisK on Sept 3, 2006 21:24:49 GMT -5
Use a digital volt meter. Go buy one if you don't have one. If you are in the USA and live near a Sears store, they have one on sale for $10 thru tomorrow. Radio Shack, the Home Depot, Lowes, yada yada yada, have them. Measure the resistance of each pickup directly across its output wires. Disconnect them first for surest results. If one measures nearly zero Ohms on the 20K scale, its shorted and bad. If one measures over 25k to 30k Ohms (I'm being real generous here) on the 200K scale, its open and bad. If one measures between about 5k Ohms to 15k Ohms or so on the 20K scale, its OK. If the neck pickup measures out OK, then the problem is in the neck volume pot or the switch. Having a digital volt meter will then enable the testing of the rest of the circuit. Troubleshooting without a volt/Ohm meter is like driving with your eyes closed. You might get real lucky, but I doubt it. Linear deduction is. Guessing isn't.
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Post by bladerunner on Sept 3, 2006 21:50:02 GMT -5
Hello again.. I don't have a volt/ohm meter.. I will have to get one and test this out.. in the meantime I did this:
with selector switch in middle position and all volume pots and tone pots set to 10, I was able to tap all the volume pots and tone pots and can hear a reply / echo reply after tapping with my finger.. I did this exercise again with the bridge position and was able to hear tapping reply on all four pots (2 volume and 2 tone)
as well I took a screwdriver and at the middle selector position I taped the bridge and neck pickups, (scraped along magnets) and was able to hear both pickups working.. when in the bridge position the bridge pickup sounds off greatly and I can hear as well the neck position tapping (but not as loud)
at the neck position tapping/ scraping the screwdriver i did not hear any sound coming out of either pickups....
this mean anything?
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Post by sumgai on Sept 4, 2006 2:37:13 GMT -5
br, Yes, it means that you need to do what Chris suggests, above.
I gave you a method whereby you don't need a multimeter, but you do have access to a soldering iron. Chris's method is more sure, and much less time consuming, if you already have a meter.
But at this point, you've done enough horsing around...... Go buy that meter, make the above tests, and report back with your results. ;D
sumgai
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Post by bladerunner on Sept 13, 2006 17:56:56 GMT -5
hello there again.. I apologize for the late response... Other life issues got in the way... I finally fixed my issue.
My original thought about the 3 way selector was correct.. Thru the process of elimination I was able to determine that the pots / volume / tone pots and pickups and wiring were not at fault.
I simply retested the 3 way switch (the one the I bought to replace the old defective one).. basically reversing the wiring for the neck and bridge pickups determined that in fact both pickups works... as well as tested the pots...
It came back down to no response from one of the terminal ends of the 3 way switch....
So my assumption in replacing the old defective 3 way switch with a new one that I purchased, I assumed that would of eliminated this piece... Only after that I realized no "buzz" input coming out of the newly replaced 3 way switch and taking that switch out and putting it on another similiar les paul guitar that I realized in fact I bought a new defective switch..
You can imagine the steam and anger after realizing I just bought a new defective 3 way switch..
I want to thank everyone on this board with there knowledge and deductive reasoning and troubleshooting.. You guys provide an incredible wealth of knowledge and appreciate your input
Peace
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