pickup hum, tone pot not working

[bobbycheetah]

Hello, I have a Hamer Slammer Series Daytona - (Korea). The top tone pot for neck pu is not working. Here is a link for a short video that I took testing the pu's. Hopefully the volume is loud enough to hear the humming. Is this "normal" humming? I realize that when the switch is in the 2nd position - it cancels out the major hum, leaving only a slight higher pitched hum. Would that higher pitched hum indicate a grounding issue?

I do realize that the top tone knob is for the neck pu and bottom tone knob is for the middle pu.

As for the top tone pot not working - I don't see any wires disconnected, and when I checked for resistance, the readings indicated the same as the bottom pot that does work - unless I'm doing something wrong. Hopefully, the video might help with any suggestions or help you can offer. Thank you in advance!!

https://www.dropbox.com/s/7lv38t0ai7dkn47/guitar-buzz.mov?dl=0

[velorush]

You've definitely got something going on with the wiring given T1 is inoperable. Does the "low hum" remain the same when you change the orientation of the guitar in the room (e.g., take a quarter turn in either direction)? Does it remain the same in other rooms or in other structures?

To me it sounds as if you have a RWRP middle pickup that is humbucking in positions 2 and 4, but the hum in the odd positions is way too loud.

Posting some photos of the back side of the pickguard (wiring) will be really helpful.

Also, is this a new guitar to you and it's been this way since acquisition, or is this a guitar you've had and suddenly this started up.

[bobbycheetah]

thanks for the reply. The hum remains the same no matter which room or if I move around - change orientation. I purchased the guitar new from my friend's music store a long time ago. I didn't really play it at all until I just recently started getting into it. I don't recall whether the issues existed way back when during any rare occasion that I decided to play it. I have shared a photo of the wiring. I have not made any attempts to do anything, other than try to measure the resistance, and to try some Deoxit in the pot.

https://www.dropbox.com/s/296gt0y9wmvc7ne/hamer-wiring.jpg?dl=0

Yday I purchased a 1993 USA Peavey Predator in great condition for $100. I decked the bridge and adjusted the intonation. Neither tone pots work, but it really sounds nice. There is only a very slight hum - (you really have to listen for it) when in the 1,3,& 5 positions which I'm thinking is "normal". Could the previous owner have disconnected the tone pots to just use the amp's tone controls? Is that something normal that guitarists would do?

[Harkonnen]

If neither tone pot works but you can measure a resistance change when you spin them, probably the simplest explanation is that the ground connection is not working and they are just functioning as open circuits i.e. doing nothing. Is the back of the pots connected to the strings? If so, can you check that the connection is working?

Edit: and of course check whether the connection to the ground lug in the output jack is working.

[bobbycheetah]

i haven't looked at the Peavey pots yet. Having too much fun playing it at the moment. My main focus tho is on the Hamer. Thanks for the reply!

[Harkonnen]

Sorry bobbycheetah, I didn't realize you were talking about a different guitar, thought the Peavey was an amp. If the faulty pot in the Hamer is changing its resistance value then there's two things that can go wrong there: either the capacitor is broken or it is not properly connected to ground. I'm looking at your wiring pic, but I am not sure what is going on with the faulty pot. I can see the yellow cable going from the switch to the middle lug of the pot, but I am not sure which cables are connected where. Can you take a more clear pic of the wiring there? There should be a ground cable from the right (I think) lug to a tone cap to ground, but I can't see none.

[velorush]

The Hamer: I don't see a connection between T1 and the capacitor.

Here's a shot of a Strat I wired up a few years ago. Note the connection between T1 and T2 using the capacitor's lead (could also use a wire, also, sorry about the quality - the shot was of the entire pickguard assembly and I cropped and zoomed in Photobucket to get you closer):

Here's another that Fender actually wired up. This one was stock when I owned it, then left me and came back. The superfluous solder and odd termination of the capacitor's leg (goes to ground on the volume pot - star-grounding taken to the extreme?) leads me to believe there was some monkey business in the interim. Pretend that black-covered leg of the cap is grounded on the pot and you should see the similarity:

And lastly, here's a set of pots (sans pickups) I just happened to have on my desk right now:

Also note, I typically place the cap on T1, but only because that's the way Fender seems to do it (and it typically is less trouble to get into a vintage routed body), but it can be placed on either pot assuming the same connection is made to the alternate pot.

Let me know if this does it for you.

[velorush]

Ummmm... any developments?

[bobbycheetah]

Thx for everyone's replies. Work has kept me busy. Also, I've got a Hamer Daytona Wiring diagram but it's fuzzy and hard to read. I will try looking for another one that's clearer. Currently, I don't have any soldering equipment. I've been researching many how-to's, and making a list of things i need. Just not sure if I want to go thru all that for just fixing one guitar. But on the other hand, I don't have the means to take it to someone right now.

I just noticed too that my tone pots are 500K. I thought 250K was the "standard" for 3 single coil pickup guitars. I can get resistance readings from T1 pot, and can see the variable resistance readings when I measure using the wiper, so does that mean the pot itself is still fine and that my issue is a bad connection?

(sorry, can't rem how to imbed the pics into the post. here are links to dropbox)

https://www.dropbox.com/s/oxrbhi96y88e3wc/2015-05-16%2009.38.52.jpg?dl=0

https://www.dropbox.com/s/3biwhszaweg9a3k/2015-05-16%2009.39.19.jpg?dl=0

https://www.dropbox.com/s/4eymy9n21m6s057/2015-05-16%2009.40.14.jpg?dl=0

[Harkonnen]

I'd say there's no "standard" tone pot, it's just a matter of preference. The tone circuit is just a resistor in series with a capacitor to ground. Your guitar signal wants to get to ground as easily as posible, and it has two ways: through the amp or through the tone circuit. Now, the signal is kind of a lazy bum and it will go through the easier way it can find. The bass part of the signal hates capacitors, so it will always go through the amp. The trebles like the cap just fine, and that's where the tone pot comes into place. The higher the resistance of the tone pot, the more the trebles prefer to go through the amp (and thus, to your ears). So adjusting the pot to high resistance gives you a brighter signal (more trebles towards the amp) while dialing it for low resistance gives you a warmer tone (more trebles through the tone circuit to ground). Long story short, using 500K tone pots allows you to have a brighter sound than using 250K ones. No alternative is better, just different.

Regarding your issue, I'd say it's almost certainly a problem with the grounding of the tone pot. I'm not sure what's going on there, maybe there used to be a capacitor inside that brown-ish sleeve that grounded on the pickup guard shielding? Maybe velorush knows what's up with that, me I've never seen such a thing (not that I've seen that many anyway).

[velorush]

Here's the Duncan Strat wiring diagram (click the picture that pops up with the link for a printable PDF - ignore orange line in the photo below, it was just the closest JPG I found available):

...and here's your guitar:

Notice in the wiring diagram and in the photos I presented earlier, the tie between the middle lug of T2 and the Capacitor on T1. That connection is not present in your guitar. Since the capacitor in your guitar resides on T2, the connection must go from the center lug of T1 to the outer lug (with the capacitor) on T2. Regardless of any other problems that may or may not be present, T1 is not connected to the capacitor and therefore cannot work.

If you need proof, forget the soldering iron and just connect a wire by twisting it onto the lugs (take care it doesn't touch anything else). Take a screwdriver and tap on the neck pickup poles, turn down T1 and you should hear treble roll off. If that works, problem solved (that one, at least) - get someone to solder it up and put the guitar back together.

500k pots: a 500k volume pot will change the resonant frequency of the pickup. You'll hear more treble (probably too much) and a different resonant peak. If it sounds good to you, then it is good (quoting Veatch). The 250k volume pot will reduce the treble found present in the typical Strat pickup (it'll sound beefier, all things remaining equal). A 250k volume pot is readily available and cheap. I'd go with that.

A 500k tone pot will be the same as a 250k tone pot when turned down to a value of 250k (probably not half way through the sweep as it is likely audio taper). Again, 250k is typical in a Strat for a reason, but it's not going to make a drastic difference on a tone control, only in how quickly the treble roll-off is accessed through the sweep of the control.

[bobbycheetah]

Thanks for all your help and the info. I'm still working on getting a wire tied to each connection - it's been frustrating b/c the space is so tight and hard to get in there to twist a wire around the connections. btw, I'm using a wire from a twist tie where I stripped each end. Thought it would be easier to work with. Is that ok, or to thin?

[bobbycheetah]

Hey, I'm still working on it.

In the meantime, I just found a very nice Slammer with a tobacco burst finish. The tones work fine. This baby is quite hummy too in the 1-3-5 position. eventually I'll take it apart see how it's configured. I'm thinking that the hum is just "natural" for these guitars? A real guitar player friend of mine who does all his own work says the pups are as cheesy/cheap as he's ever seen w/the magnets on each side of the poles. Thanks again for everyone's time and info!

[bobbycheetah]

Got the tone pot working attached a wire from the lug the cap is on to the outer lug on T1 (under the green wire) - that was how my new slammer was set up. Now i have to see if can do anything about the major hum in pos 1-3-5. I was incorrect about the new slammer I just got - it does have some hum but it's not that bad - and from what I understand is "normal" for single coils. I was reading that it could be the ground connections not being very "conductive" and was thinking about unsoldering and re-soldering them.

[Victor (Fret Friend)]

I'd say you need a cap on the other tone put...

Personally, I'd put a cap on the other tone pot and I'd put the green wire on lug 3 (from 2) and then I'd bridge lugs 1 + 2 (yellow wire)... That will give you the tone-split mod which gives separate tones for middle/neck on the middle pot and tone for the bridge pickup on the other pot. My customers love this mod...

Basically you'd be doing Example 2 here; http://www.premierguitar.com/articles/Stratocaster_Tone_Split_Mod

If that don't float yer boat = just copy Example 1. (I can see your 5-way is different but all yo have to do is look at the bridging wire between one side to the other [on the 4/4 5-way] and work out that the bridging wire = lugs 4 & 5 on your [8-in-line] 5-way. Good luck

Got the tone pot working attached a wire from the lug the cap is on to the outer lug on T1 (under the green wire) - that was how my new slammer was set up. Now i have to see if can do anything about the major hum in pos 1-3-5. I was incorrect about the new slammer I just got - it does have some hum but it's not that bad - and from what I understand is "normal" for single coils. I was reading that it could be the ground connections not being very "conductive" and was thinking about unsoldering and re-soldering them.

Re-soldering old joints is always a good idea

[bobbycheetah]

I think I'm good with the way it is now. Notice the ground solder joints on the pots - see the brownish color under the joints - is that from some kind of chemical (flux?) that may have been used before applying the solder, or is that a discoloration that indicates a problem? All grounds test successfully with the mm. I've ordered some copper foil tape to line the cavity. I've seen a few vids on doing this. Any thoughts on that - i.e. go for it or don't waste your time? Thats as far as I'm going with this guitar for now. I may try replacing the pickups with some Lace Sensor later on down the road.

On a diff topic - I took apart my Peavey Predator yday so I could get at the tone pots and use some DeOxit - perfect. Had to take the neck off tho to get the pick guard to come out. The wiring is very similar to my Slammer - the cap is on T2 (middle pup pot). However, there are no ground wires from T2 to T1, and T1 to Vol pot. All grounding tests fine tho. I'm thinking the ground is occurring via the silver foil tape on the back of the pickguard and the tone pots going thru it is making contact? Don't know why I didn't take a pic. Oh well, gave it a good cleaning, body/neck/frets, & new strings. It looks and sounds nice. Waiting for strings to come so I can clean up the new Slammer I just bought

[velorush]

Paragraph One: the brown discoloration is flux. It de-oxidizes the underlying metal, helps the solder to flow and to stick to where you want it.

Paragraph Two:

Macro concept: you want one and only one route to ground for the entire guitar.

If your pots are sitting on a piece of metal serving as a shield - a great example is the early Hamer triangular shield, shown here:

or one of my favorites, the vintage Strat steel shield:

or more typical these days, the foil-glued-to-the-pickguard shielding shown here:

the connection between the pots and the shield serves as the ground. If you connect the pots with an additional ground wire (as Fender does from the factory) you are providing a second conduit to ground. This works as a very effective RF antenna (i.e., a hum antenna - and good on Peavey for leaving out the hum antenna!).

In your Hamer Slammer, choose your ground, but choose only one (as Peavey apparently did). Either electrically isolate the pots from the shield, connecting the shield to the ground circuit at another point, or eliminate the wires creating the second ground. There's a great (old) article on this concept here along with other articles on modifying your Strat-type guitar to quieten it down.

Single coil pickups by their nature hum. Different single coil pickups hum different amounts and efforts to curb this often change the nature of the pickup. Bill Lawrence Keystones are noted by many as some of the quietest (and best sounding) true single coils on the market (not to mention being incredibly inexpensive for the engineering involved!). But there are a number of things you might try before replacing pickups, especially if you like the fundamental tone.

I like Vic's idea of a second tone cap only when I have a set of pickups where the cap value needs to be different for the different pickups. Fender wired it this way because: 1. it works fine and 2. it halved the number of capacitors it had to buy to produce Stratocasters. Leo was all about saving money.