Help! Strat HHH build is humming (newbee alert!)

[ddd]

Hi Everyone

Newbee alert!!! (thanks in advance your patience! )

I can really use some help diagnosing my pickguard build. I took my time and built it as pretty as I could. The problem is the dreaded hum -- probably a ground problem since it gets somewhat better when I touch the strings or bridge (but doesn't go away)....It hums in all 5 positions of the 5-way switch, but it is a little less when just the bridge is selected, and a little worse when just the Neck is selected.

This is a fresh build - new pickguard and pots. However 2 of the Pickups were used in a previous build (where they worked fine, no humming). This should be really simple - 3 pickups, 5 way switch, 1 Volume, 1 Tone. The switching, volume, tone and pickups all work the only problem is the hum....much worse than a single coil.

I have ruled out the cable and amp, since I have a separate 2 single coil guitar (Fender Lead II with Neck and Middle pickups from a strat wired with a 3-way) that doesn't hum when its in humbucking mode.

Here's my diagram of what I built: The pots are 500K and the Cap is a Fender 0.03 uF.



Here's the picture:



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Is there something obvious that I messed up here? Thanks in advance for any help!!

DDD

[Yew]

you have the pickup colours right



do the volume and tone controls work fine?

Have you put the ground to the sleeve of the jack, or the tip?

[sumgai]

ddd,

Hi, and to the NutzHouse!


It all looks good, so the only thing I can suspect would be the wiring colors for the pickups themselves. If you haven't already done so, disconnect one of the pickups entirely, and use a meter to make sure that the wires are colored correctly. From your description, it sounds to me like you've got one coil ungrounded, leading to what we call a "hanging hot". That's a coil that's hooked to the output that can act like an antenna for hum, etc.

HTH




sumgai

[newey]

Have you put the ground to the sleeve of the jack, or the tip?

I like Yew's instincts here. Easy enough to check it, and an easy mistake to make. Make sure which jack connection is the tip- that one should connect to the center terminal of your volume pot; the other one is grounded.

If it's the opposite of that, it would explain undue noise.

[ddd]

Thanks for the quick replies!!!

Volume and Tone work fine.

I did check the jack wiring (black/ground is to the sleeve and white/hot to the tip). In desperation, I even rewired it incorrectly to see how much worse the hum would be -- it was much worse!! So I put it back the way I originally had it.

So that leaves the "Hanging Hot" -- I had a crapy Radio Shack multi meter and measured the resistance of the pickups (between the green and red wires) -- they were all close enough to spec (7.6K for the DP188 and like 12K for the DP180 and DP226). I didn't check the ground wire itself.

Another thing I noticed is when the guitar is plugged in, and I have the pickguard exposed, if I touch the insulation on the white (hot out) the buzz gets worse -- is it possible my hot out is acting as an antenna too? This doesn't make sense because the original hot out wasn't coax....

I returned my multi-meter because it couldn't give a stable reading across the a new 500k pot. It was a $20 digital one from Radio shack -- maybe it was user error...but I couldn't get it to give consistent measurements.

So it looks like I need to get a better multimeter -- I can go back to Radio shack -- is there a meter you all would recommend?

Thanks again for all your help here. I really want this to work (so that I can take on more ambitious wiring projects!)

[sumgai]

newey and yew,

ddd stated up front that when he touched the strings, the noise got quieter - that can't happen if the jack's connections are reversed.

~!~!~!~!~!~

ddd,

While wire-color diagrams are fine, they are only meant to tell you what is supposed to be, not necessarily what really is. For that reason, you need to take a meter not only to the entire pickup, but to each coil of that pickup. This is especially true when one can access all of the wires (two from each coil) as you can. (Just break open the taped connection and temporarily separate the wires). Only in this way can we be sure that the two wire colors that are alleged to be assigned to a coil do indeed connect to that coil. Factories sometimes do make mistakes!

As to that white wire getting more noisy as you touched it, that's exactly what we'd expect. It wasn't the white wire, it was the connection out to the jack ('s hot connection) that did it. The quickie test would've been to touch the other end of that same coil, and see if it got any louder. While not a perfect test, it can lead you closer to a solution.



Radio Shack has some better quality meters, but you'll pay for them. If you have a Lowe's or a Home Depot nearby, or even a Sears, you can find good quality meters in their electrical departments. Sears will cost slightly more, for the same thing, but it's a matter of convenience to you, which store you might choose. Also, I'd tend to stay away from auto parts stores, I've never seen a reasonable quality meter in any of them. (But that may be my prejudice showing.....)

Other than that, if you can wait, you might shop around the web for a good deal. We can help you out with that, should you decide to try it that way.


HTH




sumgai

[ddd]

Thanks!

I'll check out the multi-meters at Home Depot -- there's one near by... In the mean time, I did a couple tests that should help. Recall that I have used two of these pickups in a previous build (the DP180 and the DP188) and worked fine in that guitar (so I have to figure that they are wired correctly internally). Unless I broke them in the de-install, re-install, they should be fine...

Pickup Test:

O.k. so here's what I did: First I removed all 3 of the green/ground wire pairs from the volume pot. I plugged the guitar in and there was two distinct noise sounds -- A low hum (I presume is 60htz) and the usual buzz that I've been hearing since I assembled this project. The noise was noticeably louder in the 2 and 4 positions (dual pickup positions) -- I take that is is because the red wires are still connected and the pickups are acting as antenna.

Next I re-attached the Neck pickup green/ground pair to the volume pot. With the 5-way in the Neck-only position, I should have a one-pickup "Neck only" guitar -- since the other two pickups are now electrically isolated (no connection to ground and not connected through the 5-way to the output of the switch). I plugged the pickguard back in my amp and here's what I heard:

Neck = Buzz
Neck+Middle= louder Buzz
Middle = Buzz+Hum
Middle+bridge=Buzz+Hum
Bridge=Buzz+Hum

This seems to make sense (I get "Hum" when no Humbucker is in the connection).
The results for a Middle and Bridge are similar (i.e. Middle has Hum +Buzz in 1&5).

I then reattached all the green/grounds to the Volume Pot and now I'm back to "buzz" in all positions. And as before, the bridge PU seems to buzz a little less.

Pickup Test Result: I believe this tells me that my pickups are fine...or they are all broken in the same way! -- but remember 2 of these worked in the other guitar...


Test 2 - Reposition the Jack/Ground wires

Based on the first test, I'm guessing that the problem is in my pots/jack/ground wiring. I moved the Jack and Bridge Grounds to the Volume POT. The buzz seems to be less (especially when I touch the bridge/strings), but it might just be wishful thinking...

Any ideas/suggestions?

[fergus]

I would replace the wire to the output jack with shielded cable, it looks like it isn't but it's not so clear.

[Deleted]

Just some silly thoughts :
1) Is there a circuit between a ground "terminal" (as the pot's top) and the tremolo?
2) grounding the two pots together as shown in your photo is not needed, it is a ground loop. Grounding in this case is provided through the aluminum shield in the pickguard. No need for additional wiring between the pots.
3) Why don't you start with *one* pickup and see how it goes? Rails are humbucking so at least at positions 1,3,5 you should have zero hum. Start with the pup alone and a cable directly to the amp (with no rest of the guitar involved yet!). Then start adding additional elements until you get your first buzz-hum. Then you will have found the problem!

[ddd]

Thanks again for the replies. Here's an update:

I replaced the volume->jack cable with a shielded cable and that helped quite a bit (thanks fergus!). The noise is now manageable -- its almost quiet when I am touching the strings but still buzzes when I'm not.

Following Pyros' suggestion, I think I'll start over and build/measure the noise at each step (all the changes and re-soldering have made the build much less "pretty" so I want to clean it up anyway!).

I've also learned quite a bit about the sources of hums and buzzes, I'll write that up too and post it.

Thanks again to all who offered suggestions!

[Deleted]

Is the wall socket grounding adequate?

[ddd]

I haven't test the wall socket, but my dual single-coil guitar doesn't buzz when its in humbucking mode: Its a Fender Lead II with the neck and middle(reverse-wound) pickups from a Strat. I figure if the problem was the
socket/amp/cable then I'd have the same problem on both guitars.

In single-coil mode, the Lead II buzzes much worse than the new HHH Strat build. In humbucking mode the Lead II is a little quieter than the HHH Strat. I think with a careful rebuild and some more shielding, I can quiet the HHH Strat to the Lead II humbucking levels.

The HHH Strat is really much better than when I started. In fact, I could probably live with it as it is now since is essentially quiet when I'm touching the strings.

Thanks!