Does the wiring on this Vintera Jazz look right?

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easymeow
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Does the wiring on this Vintera Jazz look right?

Post by easymeow » Wed Dec 30, 2020 5:08 pm

Just opened up a recently acquired Vintera Jazz. I'll never be accused of being an electrician, but this looks off to me. Shouldn't there be black ground wires running between each pot? And both pickups appear to be grounded to the same pot. Shouldn't each pickup's relative ground wire run to that pickup's pot?
Image here: https://imgur.com/OxF89ru

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Re: Does the wiring on this Vintera Jazz look right?

Post by timtam » Wed Dec 30, 2020 5:56 pm

Usual Fender spaghetti wiring, but all electrically 'OK' (shielded conductors would be better). All the pots are on the same metal plate as the (grounded) output jack, so their bodies are all automatically grounded. On guitars with controls on grounded metal plates, Fender's wiring designers sometimes seem to jump back and forth between going with that approach or adding the (redundant) pot body ground wires as well. It makes no electrical difference (some regard it as added security in case pots come loose and they somehow lose contact with the plate .. but just fix loose pots before that happens). And ground is ground in a guitar, so pickup ground wires can be wired to literally any grounded location that is convenient. I personally never run grounds to the back of pots - it's such a 'quick and dirty' 1950's technique that is not seen anywhere else in electronics - an electronics student would probably be failed for grounding that way (or using unshielded conductors).
https://www.fmicassets.com/Damroot/Orig ... 2_2019.pdf
"I just knew I wanted to make a sound that was the complete opposite of a Les Paul, and that’s pretty much a Jaguar." Rowland S. Howard.

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Re: Does the wiring on this Vintera Jazz look right?

Post by ChrisDesign » Wed Dec 30, 2020 9:15 pm

Yep. It’s messy, but messy wiring has no effect on tone. It looks like the plate is taking the ground to the output Jack anyway.

If i needed to replace the pots I would shield the cavity, pull all body grounds to a single point, then run that to the output Jack. But if it’s not broke, don’t fix it.
"I own a '66 Jaguar. That's the guitar I polish, and baby - I refuse to let anyone touch it when I jump into the crowd." - Kurt Cobain

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Re: Does the wiring on this Vintera Jazz look right?

Post by easymeow » Thu Dec 31, 2020 2:40 am

ChrisDesign wrote:
Wed Dec 30, 2020 9:15 pm
Yep. It’s messy, but messy wiring has no effect on tone. It looks like the plate is taking the ground to the output Jack anyway.

If i needed to replace the pots I would shield the cavity, pull all body grounds to a single point, then run that to the output Jack. But if it’s not broke, don’t fix it.
Yep, starting on shielding. First time, so the wiring threw me when it didn’t look like what I’ve seen in researching this stuff.
Thanks!

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Re: Does the wiring on this Vintera Jazz look right?

Post by easymeow » Thu Dec 31, 2020 2:41 am

timtam wrote:
Wed Dec 30, 2020 5:56 pm
Usual Fender spaghetti wiring, but all electrically 'OK' (shielded conductors would be better). All the pots are on the same metal plate as the (grounded) output jack, so their bodies are all automatically grounded. On guitars with controls on grounded metal plates, Fender's wiring designers sometimes seem to jump back and forth between going with that approach or adding the (redundant) pot body ground wires as well. It makes no electrical difference (some regard it as added security in case pots come loose and they somehow lose contact with the plate .. but just fix loose pots before that happens). And ground is ground in a guitar, so pickup ground wires can be wired to literally any grounded location that is convenient. I personally never run grounds to the back of pots - it's such a 'quick and dirty' 1950's technique that is not seen anywhere else in electronics - an electronics student would probably be failed for grounding that way (or using unshielded conductors).
https://www.fmicassets.com/Damroot/Orig ... 2_2019.pdf
Thanks! I’m going to shield and might as well replace with shielded conductors while I’m in there.

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Re: Does the wiring on this Vintera Jazz look right?

Post by easymeow » Thu Dec 31, 2020 4:03 am

ChrisDesign wrote:
Wed Dec 30, 2020 9:15 pm
Yep. It’s messy, but messy wiring has no effect on tone. It looks like the plate is taking the ground to the output Jack anyway.

If i needed to replace the pots I would shield the cavity, pull all body grounds to a single point, then run that to the output Jack. But if it’s not broke, don’t fix it.
Currently the pot that receiving the grounds is running to the output jack via the plate. Would running a jumper from that pot to the output jack run a risk of “overgrounding?”

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Re: Does the wiring on this Vintera Jazz look right?

Post by Bradley-Jazz » Thu Dec 31, 2020 5:03 am

easymeow wrote:
Thu Dec 31, 2020 4:03 am
ChrisDesign wrote:
Wed Dec 30, 2020 9:15 pm
Yep. It’s messy, but messy wiring has no effect on tone. It looks like the plate is taking the ground to the output Jack anyway.

If i needed to replace the pots I would shield the cavity, pull all body grounds to a single point, then run that to the output Jack. But if it’s not broke, don’t fix it.
Currently the pot that receiving the grounds is running to the output jack via the plate. Would running a jumper from that pot to the output jack run a risk of “overgrounding?”
Some say that would create a ground loop and could introduce more noise:

https://humbuckersoup.com/proper-guitar-grounding/

Some say that’s rubbish, and there need to be voltage differences between the grounds to cause a problem, which you don’t get in a guitar circuit like this.

I don’t know, and have guitars wired both ways which are not noticeably different in this respect. However, unless you feel you have a problem right now, personally I’d leave it alone. If it ain’t broke.... (speaking as someone who’s broken plenty of working things!)
All the cheeses....

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Re: Does the wiring on this Vintera Jazz look right?

Post by timtam » Thu Dec 31, 2020 10:27 pm

easymeow wrote:
Thu Dec 31, 2020 4:03 am
Currently the pot that receiving the grounds is running to the output jack via the plate. Would running a jumper from that pot to the output jack run a risk of “overgrounding?”
There's no such thing as 'overgrounding' or hum-generating ground loops in a guitar. There is only one ground potential in a guitar (that at the output jack). So no hum-generating current can flow in the ground lines. People wrongly extrapolate from circuits where multiple looped grounds can cause problems, like inside amps or recording studios' with multiple pieces of inter-connected gear (pedals, amps, mixers) each plugged into different mains outlets, which may or may not have slightly different ground potentials (so a loop is not always a problem there). If you think about it, every guitar with wire-grounded pots on metal plates, or continuous cavity/pickguard grounded shielding, has physical ground loops. It doesn't matter.

Having said that, neater/more easily-wired grounding schemes can be designed where most grounds run to a single point. For example, run a ground wire from the output jack ground tab to a screw-tab in the cavity, and distribute wire grounds to everywhere that needs them from there (but often some 'hops' are used as well). So it looks like 'star grounding', but it's done for wiring efficiency reasons rather than the reasons why one would use star grounding in an amp.
"I just knew I wanted to make a sound that was the complete opposite of a Les Paul, and that’s pretty much a Jaguar." Rowland S. Howard.

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Re: Does the wiring on this Vintera Jazz look right?

Post by easymeow » Fri Jan 01, 2021 7:21 am

timtam wrote:
Thu Dec 31, 2020 10:27 pm
easymeow wrote:
Thu Dec 31, 2020 4:03 am
Currently the pot that receiving the grounds is running to the output jack via the plate. Would running a jumper from that pot to the output jack run a risk of “overgrounding?”
There's no such thing as 'overgrounding' or hum-generating ground loops in a guitar. There is only one ground potential in a guitar (that at the output jack). So no hum-generating current can flow in the ground lines. People wrongly extrapolate from circuits where multiple looped grounds can cause problems, like inside amps or recording studios' with multiple pieces of inter-connected gear (pedals, amps, mixers) each plugged into different mains outlets, which may or may not have slightly different ground potentials (so a loop is not always a problem there). If you think about it, every guitar with wire-grounded pots on metal plates, or continuous cavity/pickguard grounded shielding, has physical ground loops. It doesn't matter.

Having said that, neater/more easily-wired grounding schemes can be designed where most grounds run to a single point. For example, run a ground wire from the output jack ground tab to a screw-tab in the cavity, and distribute wire grounds to everywhere that needs them from there (but often some 'hops' are used as well). So it looks like 'star grounding', but it's done for wiring efficiency reasons rather than the reasons why one would use star grounding in an amp.
Good info. And yet even Fralin cautions of “over-grounding” here: https://www.fralinpickups.com/2018/11/1 ... grounding/
“If your parts mount to a metal plate or shielding, chances are, they are already connected electronically. In this situation, running extra jumper wires would only over-ground your electronics.”

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Re: Does the wiring on this Vintera Jazz look right?

Post by timtam » Fri Jan 01, 2021 7:42 am

Unfortunately pickup manufacturers cannot always be relied upon for sound information. That Fralin page is a well-known example. Pickup making is an artisan trade. Qualifications in physics, engineering, or electronics are the exception rather than the rule.

"Over-grounding" is not a term I have ever heard in electronics. Google reveals nothing on the subject.

But it be would be very easy to test their theory by wiring grounds from pot to pot in a loop (in the way Fralin's guy recommends against), record the noise floor, and then cut one wire to break the loop and record again.
"I just knew I wanted to make a sound that was the complete opposite of a Les Paul, and that’s pretty much a Jaguar." Rowland S. Howard.

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Re: Does the wiring on this Vintera Jazz look right?

Post by Scout » Fri Jan 01, 2021 5:43 pm

timtam wrote:
Wed Dec 30, 2020 5:56 pm
Usual Fender spaghetti wiring, but all electrically 'OK' (shielded conductors would be better). All the pots are on the same metal plate as the (grounded) output jack, so their bodies are all automatically grounded. On guitars with controls on grounded metal plates, Fender's wiring designers sometimes seem to jump back and forth between going with that approach or adding the (redundant) pot body ground wires as well. It makes no electrical difference (some regard it as added security in case pots come loose and they somehow lose contact with the plate .. but just fix loose pots before that happens). And ground is ground in a guitar, so pickup ground wires can be wired to literally any grounded location that is convenient. I personally never run grounds to the back of pots - it's such a 'quick and dirty' 1950's technique that is not seen anywhere else in electronics - an electronics student would probably be failed for grounding that way (or using unshielded conductors).
https://www.fmicassets.com/Damroot/Orig ... 2_2019.pdf
Did you find a source for a mini terminal block? I use a small copper lug and screw it to an open spot in the cavity.

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Re: Does the wiring on this Vintera Jazz look right?

Post by timtam » Fri Jan 01, 2021 6:31 pm

Scout wrote:
Fri Jan 01, 2021 5:43 pm
Did you find a source for a mini terminal block? I use a small copper lug and screw it to an open spot in the cavity.
Space is at a premium in many cavities so I too use solder terminal lugs, all screwed to a common ground location in the cavity. The big ones can be used on pot shafts to ground the body, instead of grounding to the back of pots (where pots are not mounted on grounded metal plate or shielded pickguard and so already grounded).
Image

In hollow/semi-hollows (where working through the f-hole is a pain), I use the smallest size screw terminal blocks (smallest current rating = smallest size), cut to the number of terminals needed. Once you have inserted a screw-terminal block between pickups and controls, you can easily remove either pickups or controls, without having to pull the whole rig out.
Image

There are a range of other screw-terminal block styles, but none are particularly small because they are designed for use with PCBs (printed circuit boards), so they are tied to the common PCB hole spacing. But some manufacturers of solderless guitar wiring harnesses use them.
Image

There are also several styles of small push-terminal blocks, but I haven't tried them, eg
Image
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Re: Does the wiring on this Vintera Jazz look right?

Post by easymeow » Mon Jan 04, 2021 4:43 pm

timtam wrote:
Thu Dec 31, 2020 10:27 pm
easymeow wrote:
Thu Dec 31, 2020 4:03 am
Currently the pot that receiving the grounds is running to the output jack via the plate. Would running a jumper from that pot to the output jack run a risk of “overgrounding?”
Having said that, neater/more easily-wired grounding schemes can be designed where most grounds run to a single point. For example, run a ground wire from the output jack ground tab to a screw-tab in the cavity, and distribute wire grounds to everywhere that needs them from there (but often some 'hops' are used as well). So it looks like 'star grounding', but it's done for wiring efficiency reasons rather than the reasons why one would use star grounding in an amp.
But on a Jazz, since the plate grounds everything to the output jack, and copper tape shielding will touch the plate via a couple tabs, do I even need a wire connecting the cavity shielding to the pots?

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Re: Does the wiring on this Vintera Jazz look right?

Post by timtam » Mon Jan 04, 2021 7:01 pm

easymeow wrote:
Mon Jan 04, 2021 4:43 pm
But on a Jazz, since the plate grounds everything to the output jack, and copper tape shielding will touch the plate via a couple tabs, do I even need a wire connecting the cavity shielding to the pots?
If the cavity shielding reliably contacts the control plate (or pickguard shielding) on which the output jack (whose tab/rim is the source of ground), then the cavity shielding will be grounded and does not need a ground wire. But I usually tend to run one anyway (saves me wondering if I've remembered to verify contact between plate and cavity shielding).

I usually have a 'grounding plan' when wiring, that lists where everything that needs grounding is going to get its ground from. That process often shows up ways of refining ground distribution. I rarely follow grounding schemes in published wiring diagrams exactly.
"I just knew I wanted to make a sound that was the complete opposite of a Les Paul, and that’s pretty much a Jaguar." Rowland S. Howard.

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