Hum in a H150CM

[emery7columna]

I have a modded H150CM. It has the RS Guitarworks electronics upgrade and Lollar Imperial pickups. I notice a lot more hum when it's switched to the neck pickup. My guitar tech has been over the guitar and can not find any reason why there is hum.

 

Everything is grounded. I also have every cavity shielded. Is this normal to expect from this guitar? I never noticed any hum when I had the regular electronics and the Seymour Duncan '59s.

 

I sent the first pickup back to Jason Lollar and he sent me back a brand new neck pickup and told me that if I still get the hum, it has got to be with the wiring of the guitar, not the pickup. BTW the prior neck pickup was tested by Jason and found to be fine.

 

I've read on the Les Paul Forums that a certain amount of hum is inevitable with Les Pauls.

 

Should I just ignore the hum?

[pushover]

To state the obvious... Don't ignore the hum.. Something is probabaly wrong somewhere..

 

When a guitar is plugged in, it is an electical curcuit and if there is a hum it's bcause there is something amis.  I cannot tell the extent of the hum from the tone of your email. Also.. I don't want to speculate about things I can only conjecture about, which are things I can't possible observe 1st hand. But don't ignore it.. Bring it to a good tech and they can help you figure out what's going on.

 

My own experience is that we "humans" are part of the circuit and that a guitar is better grounded when we're touching it, but it shouldn't hum at all when we're playing the thing...

[golferwave]

 Did your tech check the 3 way switch? With the RS upgrade and hum only in the neck pickup that sounds like it may be the problem.

[big bob]

hum can be caused by many things, was the amp properly grounded, ie three prong, does the room have a dimmer switch? you may want to do a google search on hum/buzz.

[BigMike]

hum can be caused by many things, was the amp properly grounded, ie three prong, does the room have a dimmer switch? you may want to do a google search on hum/buzz.

 

What Bob said. Back in the late 70s I had a hankering to buy a BIG Celestron telescope - I need major bucks to swing the deal. SO I sold my '66 Blackface Fender Deluxe Reverb and a '65 Rickenbacker 360 to a kid at work. He came back a day later pissed as hell at me... Said it hummed like crazy and I cheated him. Well I told him to bring it back to work and I'd give him his money. We tried the outlet in his office, NO HUMM, tried it in my office, NO HUMM.... Turns out he had a dimmer switch on the circuit he plugged the amp into at his house. I should have taken the stuff back - I sold it to him for what I paid for it when I got it. $300.00 for the Deluxe and $150.00 for the Ricky...

 

 

Try flipping the ground switch on your amp too - it does have one right ?? (or am I spoiled by old Fender designs ??).

[emery7columna]

There is a switch that is never on that controls an overhead fan. There is also a rocker switch in the room that will turn on a lamp if I have it plugged into the right socket. I can't remember what socket it is but it will turn on a light. Does that sort of count as having a "dimmer" switch in the room?

[Thundersteel]

Is the fan ever turned on? If so, that could be your problem.

 

Have you tried plugging the amp in another part of the house?

[brentrocks]

flouresent lights

[cosmikdebriis]

I notice a lot more hum when it's switched to the neck pickup.

 

Firstly is the hum mains frequency? I'm pretty sure you guys run at 60hz whereas we're 50hz. If you're not sure what mains hum sounds like. turn your amp up loud without anything connected.

 

Secondly, and the reason I've quoted you, is that I'd be pretty certain the fact that the hum changes between pickups would discount dimmer switches, fluorescent lights and other sorts of mains interference.

 

How is the hum if you have both pickups on at the same time?

 

As an experiment I'd run a thin piece of wire between one of the pickup adjusting screws (on the neck pickup) and the bridge/tailpiece. This should check if the pickup housing is earthed/grounded properly.

 

Another problem with earthing can be an "earth loop" whereby, somehow, you can have too many earths/grounds I've never really understood that though.

[backline]

...Another problem with earthing can be an "earth loop" whereby, somehow, you can have too many earths/grounds I've never really understood that though.

 

 

That's an excellent point. Too many ground paths can contribute to hum. Check that front pickup and make sure it's only grounded by either the sheild jacket of its cabling, or the ground wire if it's a four wire. Not both.

If it is doubly grounded you can disconnect the sheild jacket at either end and interupt the ground loop's extra path. Microphones with XLR's are wired this way for the same reason.

[slider313]

If it's just the neck pickup, I would suspect the volume pot for that pickup. Sometimes, when pressing the knobs back on the shaft, the pots housing can be compromised. Check to see if the pots housing is "loose" in any way. If you want to attempt it, try soldering in a new pot.

[Hfan]

Hello everyone. I was doing some research and came upon this thread. I have a recently acquired H150 which had after market p ups installed (stormy Mondays). Its my first 150 and I love it but I think I can improve upon several aspects, I'll start with what I believe to be a grounding issue.

 

It looks like the grounding scheme may have been changed to some extent. I can see that the treble tone control had, at one point, two ground solder points on the back of the pot. It currently has only one solder point in use. I have been getting quite a bit of hum with occasional popping noises which I assume to be static discharge (I can touch the p up cavity cover screws etc and duplicate this if I am not touching the strings). Occurs on both my amps (which are dead silent with nothing plugged in to them)in various outlets. I've ohmed out all the ground points and they all seem to be at ground potential. The hum/buzz stops if you touch a grounded part of the guitar. I've had the cover off and can find nothing obviously wrong. I don't know if these are higher gain p ups. I'm suspecting a ground loop.

 

My 575 with Seth Lovers has some hum but not to this extent. My single coil guitars obviously also exhibit some hum (no popping noises though) but that is the nature of the beast.

 

Does anyone have a picture of the inside of a stock 150 p up cavity? Or a link to a schematic would be  great as well.

 

I've done some searching on the Internet on this subject and there seems to be a lot of positive feedback on shielding the interior cavities and covers of solid body guitars, especially single coil types (hum reduction and increased harmonic output or something like that). I'm an old tech/mechanical guy and have recently had good success in refurbing and modding old tube amps just from what I have picked up on the web. I do not, however, have any background in tinkering with guitars although I suppose it's about time I picked up on some basics. I know that many members here are very knowledgeable on guitar repairs and mods. Does anyone routinely shield their solidbodies? I would prefer to find a simple (less time consuming) fix first.

 

Thanks in advance for any info or comments.

 

Pete

[Hfan]

I was able to get a wiring diagram from Bareknuckle Pickups and it looks like there was a ground loop.  I re soldered the ground connections as they recommend in their diagram (moved one grnd wire connection from the treble PU tone ctrl to the Bass PU volume ctrl) and the hum is much less and the popping noises (capacitors picking up and discharging a charge) is, I would say 90% less. I would consider the hum to be now at a normal level and in line with my other electrics.

 

Once again, have any members (I know some of you guys are tinkerers) tried shielding the interior cavities of their Heritages or other electric solid bodies?

[Dick Seacup]

Once again, have any members (I know some of you guys are tinkerers) tried shielding the interior cavities of their Heritages or other electric solid bodies?

 

I haven't tried it, but my Hamer's have shielding paint in the control cavities. My recollection is that it's a German (or European, at least) product and not inexpensive.

 

EDIT:  A trip to Stew-Mac might be in order. Shielding paint.

[tulk1]

I don't know if this has been suggested yet or not. Didn't go back and reread the complete thread. But if it has, then please ignore. But is it possible the guitar is humming because it can't remember the words? Just asking.

[mars_hall]

Now that was good

[Hfan]

I've seen the shielding paint, it is pricey about $40 for a pint which should do 3 or 4 guitars. There is also copper faced tape available which a grnd connection can be soldered to. You overlap it to form a connection.