|
Post by dazzaling69 on Aug 22, 2011 7:43:27 GMT -5
|
|
|
Post by newey on Aug 22, 2011 10:53:15 GMT -5
dazzaling69-
Hello and Welcome to G-Nutz2!
First, Check to see that you have not reversed the wires to the output jack. It's easy to do, sometimes you have to look twice to see which lug goes to the tip and which to the sleeve. If those were reversed, it could explain your problems.
If that's not it, post back. We'll probably need some actual photos to be able to tell anything, though.
|
|
|
Post by dazzaling69 on Aug 25, 2011 7:21:47 GMT -5
With respect, I can't see how that would be a problem. Since the earths all go to the volume pot before the jack socket it should be possible to swap earth and signal at the socket and get a working guitar both ways around.
I suspect that I have accidentally shorted the wrong terminals on the superswitch. I'll take a photo.
|
|
|
Post by newey on Aug 25, 2011 9:32:49 GMT -5
The guitar will work with the output leads switched- and you indicated that yours does so. It will however be noisy, so that's why I suggested it as a possible solution. Easy enough to check it.
|
|
|
Post by ashcatlt on Aug 25, 2011 9:41:00 GMT -5
Yeah, if the bridge is also connected to that pot case then a simple jack wiring reversal wouldn't cause the shorting effect you've described. It would tend to be noisier than you'd like, though.
These pickups have some sort of metal case or baseplate which contacts this screw you're talking about? And they've got only two wires? It sounds to me like one of these wires is Internally connected to that cover/baseplate, and you've chosen that wire as the "hot output" for the pickups. Since the bridge is connected to ground, you'll short the output and hear nothing if the metal parts of the pickup contact the bridge.
If you've got a meter, you could disconect the pickup from the circuit and measure resistance between each of it's wires and this cover/baseplate thing. The "ground" wire will measure very close to zero. The other wire will measure close to the manufacturer's specified DC Resistance, somewhere in the low kiloohm range.
If you don't have a meter you can visually inspect the pickups to find the little bit of wire connected to the slab of metal and trace that to the external wire and call that "ground", but be careful with any disassembly!
Or you could just swap both wires on both pickups and the plug it in.
|
|
|
Post by dazzaling69 on Sept 1, 2011 4:17:15 GMT -5
I looked at this more closely last night and there was a bad solder connection on the 5-way super switch which caused a lot of the problems and noise I found. However, there is still the issue that the height adjustment screw kills the sound when it's earthed. I suspect it's because the Seymout Duncan wiring diagram suggests you can change the wiring around to tap the external coils - I wonder if that causes the problem. Can anyone who understands these things take a quick look at the wiring diagram and let me know what they think? www.seymourduncan.com/pdfs/support/schematics/2hum_1vol_1tone_super5way.pdfDarren.
|
|
|
Post by newey on Sept 1, 2011 5:19:39 GMT -5
The SD diagram is fine. Any 4-wire HBs can be wired so as to select the outer coils if desired; the alternative wiring doesn't explain your problem.
If the adjustment screw contacting the bridge ground shorts the output, then one or the other of those items has to be wired to, or inadvertently contacting, your signal line.
Neither should do so; both should be grounded. The bare wire for the pickup ordinarily grounds the frame of the pup, which is in contact with the adjusters. Check that wire to make sure it isn't somehow contacting a + connection anywhere. This would probably be at one of your pots where it is grounded- make sure it isn't contacting one of the pot's lugs (well, one lug of each is grounded, so it's OK if it's touching that one . . .).
Same thing with the bridge ground- check to see that it's not touching the + somewhere.
Ash asked if you had a multimeter available. Do you? And, am I correct in assuming that these pups are 4-wire with a bare shield?
|
|
|
Post by dazzaling69 on Sept 16, 2011 5:37:53 GMT -5
Thanks for the help. Yes I guess there must be an inadvertent short there. I don't recall whether the pickup cable is shielded (as opposed to having just a single earth wire) so I will check that.
I do have a multimeter. Is there somethign useful and diagnostic I can do with that?
|
|
|
Post by newey on Sept 16, 2011 6:09:50 GMT -5
Plug a cable into the jack. Set your meter to read resistance. Touch one probe to the pickup height adjustment screw and the other to the barrel of the cable plug. You should read very close to 0Ω, indicating the screw is grounded.
Now do the same with the bridge, should have the same result.
Then move the one probe from the barrel to the tip of the plug and repeat the process. You should read "over limit" ("OL") or "out of range", depending on your meter, meaning the two points are not connected.
This may show the problem; if not then we have to look further.
|
|
|
Post by ashcatlt on Sept 16, 2011 7:59:28 GMT -5
Then move the one probe from the barrel to the tip of the plug and repeat the process. You should read "over limit" ("OL") or "out of range", depending on your meter, meaning the two points are not connected. It'll read somewhere close the DC resistance of whichever pickup is selected at the time of the test. The two points should be connected, but not by any straight wires. Also make sure the Volume pot is turned all the way up when you run these tests.
|
|
|
Post by newey on Sept 16, 2011 8:08:26 GMT -5
Yeah, my mistake. That's what I get for posting before enough coffee has been consumed in the morning . . .
If your meter is auto-ranging, you're good to go, if not, use the 20KΩ range for these tests.
|
|
|
Post by dazzaling69 on Sept 19, 2011 4:19:20 GMT -5
I solved my problem with the wiring. The diagnostic tests with the multimeter basically gave the results predicted - a resistance in the 10k range. However, when I desoldered the wiring it was obvious that there was some shorting between the signal wire and its shielding braid (on both pickups!). Stripping the cable back and wiring it all up correctly (in a star configuration for all the earths) sorted it out and it's now clean and almost entirely hum-free.
I think I may have set myself on the path of the holy grail, though. Now I want to know how little hum it's possible to achieve!
Thanks to the posters for your helpful suggestions.
|
|