Inductive Buzz From Neck Humbucker in Series

jaymenon

 I just wired up my Ibanez guitar wit Dimarzio humbuckers (taken from another Ibanez RG).
The switch is the original Ibanez 2502N and below is the wiring diagram.

 Interestingly, in position one (neck humbucker in series)  I get a lot of buzz when I take my hands off the bridge.  

That does not happen in position two (Neck humbucker in parallel). Buzz also happens in position three (both humbuckers on).

Otherwise it sounds okay...

i wonder if some one can advise me please as to what I might have done wrong?

[Imgur](https://i.imgur.com/GQIL6YJ.jpg)

Jay

Funkfingers

How much does the selector switch lever waggle in the slot? Over time, the PCB can become parted from the switch chassis, weakening the contact between the PCB tracks and the moving wiper(s).

The other classic is ragged solder trails linking adjacent terminals on the switch. 

Further remote diagnosis will require photographs.

Sporky

Aye - I'd check the connections for the neck pickup.

If it's hum cancelling in position 2 then the pickup itself must be OK; my guess is that when it's meant to be in series it's actually split.

jaymenon

It’s hum cancelling in all positions.

 What I’m experiencing is buzz when I take my hands off the bridge / strings. But it only applies to positions 1 (Neck pickup in series) and 3 (both neck and bridge pickups).

when I’m on the bridge pickup alone or positions 2 and 4, I can take my hands off the strings and no buzz...

Interesting...

Funkfingers

This might be one of those DiMarzio circuit ideas in which the orientation of the humbucker is critical. (In these instances, the wiring instructions will specify that the pickup output cable should exit the baseplate at the high E string end.) This is for electrical phase and magnetic polarity relationship reasons. DiMarzio has an annoying habit of gluing the magnet in position, making it difficult to flip.

Sporky said:

I'd check the connections for the neck pickup.

Indeed.

If I had to guess, the likeliest error is the series link between the coils. Since this link is made via the tracks of the selector switch PCB, the place to look for the problem is the PCB. 

The second likeliest explanation is that you have the red conductor for the neck pickup as the hot instead of the black. That would screw up the coil relationship and lose the hum-cancellation.

Sporky

jaymenon said:

It’s hum cancelling in all positions.

 What I’m experiencing is buzz 

Buzz, hum, same thing.

When you're touching the bridge or strings, your body is grounded through the amp and acts as a shield. So if when you aren't touching the strings or bridge, there's no hum in position 2, 4 or 5, but there is in 1 & 3, the neck pickup isn't hum cancelling in those positions.

Therefore something's up with the wiring. The neck pickup is hum cancelling in parallel (or there be buzz in position 2), but not in series.

The problem is probably at the switch. 

jaymenon

Actually buzz and hum are not the same thing.

Hum is the 50Hz phenomenon (60Hz in the US) that single coils are prone to.

Buzz is the  high-frequency sound that comes when you take your hands off the strings or bridge.  Aggravated by things such as dimmer switches.  Can be largely reduced or even  eliminated by good copper foil or graphite paint cavity shielding.

 Though you guys are going to laugh - the Ibanez S Series has so shallow a body that the switch terminals are standing proud.

The conductive foil on the inner surface of the backplate cover was shorting the terminals on the switch...

https://imgur.com/gallery/HkAC0Yb

 Now I feel like a right idiot ...

Funkfingers

Sporky said:
The neck pickup is hum cancelling in parallel (or there be buzz in position 2)

Significantly, half of the neck position pickup appears to be hum-cancelling when combined with half of the bridge position pickup. (Selector switch position 4.)

This suggests that the neck position pickup is oriented as per the official schematic diagram and that each output conductor wire soldered to the correct terminal on the bespoke PCB selector switch. 

• By itself, the *inside* coil of the neck position pickup works correctly.
• Both coils, combined in parallel, in phase, work correctly.
• Both coils, linked in series fails to cancel hum as expected.

Logically, if there were no series connection at all between its two coils, the neck position pickup should produce no signal. 

If the coils are connected but with the conductors in the wrong sequence, there will be a signal but it will be weaker than expected and fail to reject hum and radio frequency interference. 

Time for photographs of the selector switch, please.

jaymenon

 Thanks sporky and funkfingers for taking so much trouble to help me.  Please see my post made a few seconds before funkfingers last one 

Funkfingers

jaymenon said:
the Ibanez S Series ...

A pity that you did not mention the model in the OP.

jaymenon said:

... has so shallow a body that the switch terminals are standing proud. The conductive foil on the inner surface of the backplate cover was shorting the terminals on the switch.

I know. I used to own one. I traded it with Jetfire.

The S series can be quite fussy about the fit of the selector switch in the black plastic thing on the front of the guitar body.

jaymenon said:

you guys are going to laugh 

Actually, I'm prickly, restless, rambling.

Sporky

jaymenon said:

Actually buzz and hum are not the same thing.

In this context they are - both would be suppressed by a hum bucking pickup configuration.