Almost have these new electronics installed

JimmyM · #1 11-23-2010, 07:14 PM

so i took my 76 precision to the shop today for my bud bill to check its wiring because i couldn't get it right. he took a look at it and said that it looked really good, and even my clunky soldering seemed solid, but i needed to attach the shield on the p pickup to ground. so i took it home and did that and it made it quieter, but it's still got problems. i'm sure he could fix it, but i've come so far doing it on my own that it almost seems a shame to give up now. the pickups are a fender 62 reissue p and dimarzio ultrajazz humbucker...passive, 4 knobs vvtt, well shielded with metal tape under the pickups, behind the controls on the pickguard, and in the cavity. and yes, i have a bridge wire connected to ground. and sorry but i don't have a meter. might get one for christmas but i don't want to wait that long to get this bass fixed.

here's what's still wrong:

1. there is a hum that goes away when i touch the barrel of the cable plugged into it or the pots with my finger. the hum gets worse and it makes a snapping sound when i touch the pickup polepieces with my finger, and it does nothing when i touch the strings or bridge. when i touch the barrel or pots and the pickups at the same time, it doesn't make hum or a snapping sound. am i right in thinking that this is a problem with the bridge wire?

2. the p pickup will not turn down all the way but the j does. it just dawned on me that i soldered the shield wire for the p pickup onto the volume pot for the j pickup. could that have caused it? the vegas line is betting heavy on "yes," but i'd like confirmation before i pull out the soldering iron again.

thanks for any troubleshooting advice you can give me.

pnut166 · #2 11-23-2010, 07:30 PM

My $$$ is on #2.

fdeck · #3 11-23-2010, 07:35 PM

You could use any old patch cord to make temporary contact between the plug barrel and the bridge, and see if the hum goes away.

Is this always with the same amp, or with different amps? Sometimes the "healing touch" is a sign of an amp with an ungrounded chassis. This could be due to the amp, house wiring, bad extension cord, etc.

JimmyM · #4 11-23-2010, 07:54 PM

funny you mention that, francis. the amp i used happens to be a 73 super reverb with a 2 prong cable. so i pulled out another pj with humbuckers and tried it, and it did have a little noise but considerably less than the one i'm working on. so i tried the patch cable between the barrel and bridge, and also the pots and bridge, and son of a gun if it didn't get a lot quieter!

so the way i see it, i have to move the p's shield wire to the correct pot, then install a better bridge wire, and i should be in business, correct? (please say yes!)

fdeck · #5 11-23-2010, 08:37 PM

Quote:

Originally Posted by JimmyM

funny you mention that, francis. the amp i used happens to be a 73 super reverb with a 2 prong cable. so i pulled out another pj with humbuckers and tried it, and it did have a little noise but considerably less than the one i'm working on. so i tried the patch cable between the barrel and bridge, and also the pots and bridge, and son of a gun if it didn't get a lot quieter!

so the way i see it, i have to move the p's shield wire to the correct pot, then install a better bridge wire, and i should be in business, correct? (please say yes!)

Yes. It does seem likely you're headed in the right direction. Aren't all of the pots grounded? They might as well be.

Now get a proper grounded cord installed on the super reverb. That's dangerous. And unless I'm really getting old, a 70's amp isn't "vintage" enough to worry about modernizing the power cord. It's also a good time to get an outlet tester and review your house wiring and any power cabling that's gotten heavy use on the bandstand.

JimmyM · #6 11-23-2010, 09:32 PM

yeah, i do need to do that with the super. and the little airline guitar amp i have, too. but i still have to tackle this. i'll be ok for now...i always use a wireless when i gig with the super

so i fixed the ground wire and moved the p shield, but the p pickup still won't turn down all the way. the j pickup seems fine. so now i'm wondering iffen i might have a bum pickup. don't have another one around here, either.

fdeck · #7 11-23-2010, 10:16 PM

If it won't turn down all the way, it can't be a bum pickup. It must be the circuit. The only thing is that I haven't looked inside a control cavity in a decade, but I suggest drawing or finding the most readable possible schematic that you can lay your hands on for the wiring scheme that you want, then follow the circuit and ask yourself if it makes sense. For that matter, have a friend who knows nothing about wiring critique your job, and in the process of asking dumb questions, they will discover the error for you.

JimmyM · #8 11-23-2010, 10:24 PM

Quote:

Originally Posted by fdeck

If it won't turn down all the way, it can't be a bum pickup. It must be the circuit. The only thing is that I haven't looked inside a control cavity in a decade, but I suggest drawing or finding the most readable possible schematic that you can lay your hands on for the wiring scheme that you want, then follow the circuit and ask yourself if it makes sense. For that matter, have a friend who knows nothing about wiring critique your job, and in the process of asking dumb questions, they will discover the error for you.

right on, i already have a schematic drawn up so i'll go over it tomorrow when i can see again. thanks for the advice, f!

johnk_10 · #9 11-24-2010, 03:50 AM

hey Jimmy. email and i'll draw out a wiring diagram for you. if you follow it exactly, your bass will work properly.

having a pickup that doesn't turn all the way down is either you're missing a ground (likely), or a bad pot (unlikely), and has nothing to do with the pickup.

kringle77 · #10 11-24-2010, 04:11 AM

Hey Jimmy, Im having stambaugh do a "copy" with upgrades of one of my billy sheehan attitude basses. The pickups are going to be a will power p and the ultrajazz that you are using. How do you like that jazz? It should more than keep up with the output of that p right?

JimmyM · #11 11-24-2010, 01:19 PM

hey john, thanks for the offer, but i already sent you the wiring diagram i drew up and you said it was fine. so i think i just have to do what francis said and go over it. unfortunately, i have so much other stuff to do this week that it'll most likely be sunday before i can take another look.

kris, i have only used the ultrajazz in my p lyte, where it was too bright for my tastes. ended up replacing it with a duncan qp. however, i think it'll be just fine in my regular pj. it does have good output and maybe the heavier body will mellow it out a little. at least that's the plan.

fdeck · #12 11-24-2010, 01:33 PM

In any event, who needs to turn down the P pickup all the way? It's the J pickup that needs to be turned down all the way.

JimmyM · #13 11-24-2010, 07:20 PM

well i finally had a little time to look at it, and SUCCESS!!!

turns out the reason my tech told me to run a wire from the p's shield to a pot was because the wire that was supposed to be there got disconnected and wedged into everything to where we couldn't see it was loose, so it must have been shorting or something. once i pulled off the new wire and soldered the old wire back to the shield, everything was working as it should. so hopefully nothing will break as i put it back together and i'll have this bass ready to go in a couple hours!

thanks for the help, everyone! still not quite sure if i trust my soldering, but it seems to be holding up so far. i made mechanical connections whenever possible and checked the heck out of the non-mechanical ones.

JimmyM · #14 11-24-2010, 09:23 PM

arrrggggh! success is so short lived in this field. strung it up and now it's not making a ground noise anymore but it's not working again. i really can't tell what the heck's going on now. it sounds like it's working, but i still can't get the pickups to turn down and in some knob positions it sounds like distortion. i can't determine what's going on with it now because my wife went to bed and i can't turn it up enough to tell. sucks. so i guess i give up. i'll let bill finish it up. he'll fix it in 5 minutes. of course it'll take him 3 weeks to get to it, but them's the breaks

JimmyM · #15 11-24-2010, 09:50 PM

ok, so what have i learned? i have learned:

1. no matter how badly i want to do it, i will never be competent to do any repairs beyond instrument setups, tube/fuse replacements, and emergency small job soldering.

2. what it will cost me in parts, tools and time are about the same and maybe a little more than if i took it to the repair tech in the first place.

3. my eyesight has deteriorated even more in the past year than it has at any other time, my hands are just a tiny bit shakier, and my patience for this crap has found its end.

otoh, i did kind of cheap out on the parts

got good caps, but i got midline pots and a crappy jack, so maybe i'll have him start over. and i did improve my soldering enough to trust it for minor repairs if i absolutely have to. but a man's got to know his limits. i keep saying i know mine but i still keep trying to push them. no more. i am now defeated. a crumpled up shell of a man. with burned fingers.

iiipopes · #16 11-24-2010, 10:19 PM

Yes, for passive wiring, always go with CTS pots and Switchcraft jacks. Think about it: others may cost more or less, or have a better or worse reputation, but original Fender & Gibson electric guitars & basses are now going on 60+ years with their original hardware -- CTS & Switchcraft. Hang in there! It's not too far away. Sometimes those gremlins are really sneaky.

bassbenj · #17 11-26-2010, 08:10 AM

Quote:

Originally Posted by JimmyM

ok, so what have i learned? i have learned:

1. no matter how badly i want to do it, i will never be competent to do any repairs beyond instrument setups, tube/fuse replacements, and emergency small job soldering.

2. what it will cost me in parts, tools and time are about the same and maybe a little more than if i took it to the repair tech in the first place.

3. my eyesight has deteriorated even more in the past year than it has at any other time, my hands are just a tiny bit shakier, and my patience for this crap has found its end.

otoh, i did kind of cheap out on the parts

got good caps, but i got midline pots and a crappy jack, so maybe i'll have him start over. and i did improve my soldering enough to trust it for minor repairs if i absolutely have to. but a man's got to know his limits. i keep saying i know mine but i still keep trying to push them. no more. i am now defeated. a crumpled up shell of a man. with burned fingers.

Hey, Boomie stop beating yourself!

1. This stuff is just like learning to play bass. EVERYBODY starts knowing nothing! You then do some little jobs and then as you master those you move on to bigger and bigger jobs. It's just about "practice". Duh.

2. Yeah, if you only have ONE job the cost of tools and time seem to make it not worth it. But then at the second job you notice you already have the tools. And once you get going you discover that sometimes the only way to get what you want is to do it yourself! Then you have to ask how much is THAT worth?

3. Can't do much about eyesight and shakes (other than big magnifiers and just persistence). I've got a friend who was a chain smoker for years and he shakes amazingly. But he still manages to solder things OK. As for patience, that is just between the ears.

The thing about less than CTS or Switchcraft parts is that lesser pots will tend to develop noise when you turn them faster when they are cheaper. But they should work fine for a while. Same kind of thing on jacks. Non-switchcraft jacks tend to lose the springyness in the contact and you either have to re-bend them to give tension again or replace them. The guys at Alembic told me that switchcraft was the ONLY jack maker they found where the contacts didn't lose it's tension over time. Those long threaded tubular jacks used on the side of some basses are especially bad in this regard. If it were me I'd just use what you got until it starts to get noisy. That may be quite some time.

BassLife77 · #18 11-26-2010, 04:11 PM

Quote:

Originally Posted by JimmyM

. and sorry but i don't have a meter. might get one for christmas but i don't want to wait that long to get this bass fixed.

Harbor Freight has been giving them away for awhile. I have around 5 of them. I figured I can't use 5 meters at once so I just use the 9v battery that's in them

When you see .000 on the meter you have continuity. If you want a meter that checks capacitors and beeps from continuity you cant get them on ebay for around 10 bucks.

johnk_10 · #19 11-26-2010, 05:24 PM

Hey Jimmy,
you can always ship the pickguard assembly to me and i'll be happy to wire it up for you and test it free of charge.

SGD Lutherie · #20 11-26-2010, 05:37 PM

Quote:

Originally Posted by JimmyM

2. the p pickup will not turn down all the way but the j does. it just dawned on me that i soldered the shield wire for the p pickup onto the volume pot for the j pickup. could that have caused it? the vegas line is betting heavy on "yes," but i'd like confirmation before i pull out the soldering iron again.

No that wouldn't cause it because the pots should be all grounded together. It's al the same ground.

You are missing the ground on the volume for the P. So instead of shunting to ground, you only have the series resistance making the pickup quieter.

Do you have all the pots grounded together and to the output jack?