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Bad Jack, or Ground wiring issue?


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I noticed my new (and first) build actually has a slight issue when playing. The slightest pressure on the jack cuts the signal completely.

 

So I took it apart, and whipped out the multimeter

 

20201219_124644_resized.thumb.jpg.f6d01e838f2cd53bef2d474c4fd188df.jpg

 

Set to 200O or just the signal beep, I got the following results  (Key: Red: Hot / Black: Jack Ground / Orange: Nut / Dark Green: Jack Shell / Pink: Jack Ground Tip / Light Green: Tone Pot shell / Purple: Shielding / Blue: Val Pot shell )

Dark Green -> Purple/Blue/Light Green : Good

Pink (jack Ground tip) -> Purple/Blue/Light Green : Good

Black -> Pink/Dark Green/Light Green/Purple/Blue : Good - BUT, the slightest pressure on the jack and it cuts out

 

There is a very small amount of wiggle of the cable when inside the jack. The nut is quite firm but I think that mechanically it is mostly pulling the Jack tight in the body - I don't think it's compressing the Jack socket itself.

 

I've used a pedal connector here, but can confirm that same wiggle and the same issue with different cables, which all work fine in other instruments (where there is no wiggle at all) and have all been themselves tested.

 

There is no nut on the outside to tighten either:

20201219_141855.thumb.jpg.f42ad1028e74ee695bd890c0eba36e15.jpg20201219_124408.thumb.jpg.ee8be868f20b1fce26578ad6204eee00.jpg

 

Question: Is this just a bad jack (it was generic part, ordered from here: https://www.ebay.co.uk/itm/Output-Mono-1-4-Barrel-Jack-Plug-Brass-Socket-Long-Fits-Bass-Electric-Guitar/264737490450?ssPageName=STRK%3AMEBIDX%3AIT&var=564556512021&_trksid=p2057872.m2749.l2649 ), or have I not grounded this properly in some way ( I know virtually nothing about electronics )

 

If it is the Jack, is there anything I can do or try - or do I need to scrap it and try a new one?

 

Thanks

CC

 

 

 

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See, this confused the heck out of me

 

It's a three lug. There was no technical document for it (that I could find, anywhere) but the closest I found suggested it was either a Stereo capable jack, or, had a power switch on it. After wiring it up, it all seems to work fine as I said (no hum or anything) - so it's just the loose wiggle that seems to affect the signal

 

Untitled.thumb.png.707025e76a85a0a80b6e91c4844ccca5.png

3 is the longest, and was taken to be the Ground

2 is the second longest, and everything I could find suggested it was the Hot

1 is the shortest and appeared to be something else (switch, power, stereo?)

 

Do you think I got this wrong? Would it explain why it works, until the slightest pressure is applied to the cable?

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9 minutes ago, CC1 said:

See, this confused the heck out of me

 

It's a three lug. There was no technical document for it (that I could find, anywhere) but the closest I found suggested it was either a Stereo capable jack, or, had a power switch on it. After wiring it up, it all seems to work fine as I said (no hum or anything) - so it's just the loose wiggle that seems to affect the signal

 

Untitled.thumb.png.707025e76a85a0a80b6e91c4844ccca5.png

3 is the longest, and was taken to be the Ground

2 is the second longest, and everything I could find suggested it was the Hot

1 is the shortest and appeared to be something else (switch, power, stereo?)

 

Do you think I got this wrong? Would it explain why it works, until the slightest pressure is applied to the cable?

 

I was finding diagrams like this I followed:

 

Apr16_PG_CLM_Guitar-Shop-101_photo4_WEB.jpg

... and as I said, it all seemed to work - except for when the cable is disturbed

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11 minutes ago, CC1 said:

See, this confused the heck out of me

 

It's a three lug. There was no technical document for it (that I could find, anywhere) but the closest I found suggested it was either a Stereo capable jack, or, had a power switch on it. After wiring it up, it all seems to work fine as I said (no hum or anything) - so it's just the loose wiggle that seems to affect the signal

 

Untitled.thumb.png.707025e76a85a0a80b6e91c4844ccca5.png

3 is the longest, and was taken to be the Ground

2 is the second longest, and everything I could find suggested it was the Hot

1 is the shortest and appeared to be something else (switch, power, stereo?)

 

Do you think I got this wrong? Would it explain why it works, until the slightest pressure is applied to the cable?

Sorry - also - I should say, I actually don't remember which is longer out of 1 and 2 - the solder might be playing a trick on the eye there. I do remember that they were quite close in size - but one was slightly longer. 2 might actually be shorter than 1

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11 minutes ago, CC1 said:

Sorry - also - I should say, I actually don't remember which is longer out of 1 and 2 - the solder might be playing a trick on the eye there. I do remember that they were quite close in size - but one was slightly longer. 2 might actually be shorter than 1

If [this](https://www.ebay.co.uk/itm/Long-Barrel-OUTPUT-JACK-COSMO-BLACK-Fits-Ibanez-guitar-bass-stereo-mono-NEW-/392264583162) is anything to go by, the Hot tip (shortest) is left of the Ground (longest), and the middle one (Ring) is to the right of the ground.

 

So If that's the same, then I've wired mine correctly (and the sketchy soldering is making it look longer)

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Yes, that can be the issue. It's basically a stereo jack so if you've got the middle ring connected and the mono plug pushed almost in it will work until you push it a hair deeper. Then the ground part of the plug will touch the middle connector, making a short circuit.

kuva.png.cd5e2546744fd5a5f96a3adf939107b3.png

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If you've got a spare unsoldered stereo 1/4" plug you could plug it in and use the multimeter to buzz out each lug to be absoutely certain it's the issue. Technically it shouldn't make a difference to the operation of the jack, otherwise if you were to use that same jack in a guitar fitted with active pickups you'd be finding that the battery power would be lost every time you wiggled the plug.

It's also entirely possible you've just got a dud jack. I've seen those long barrel jacks, particulalrly cheap ones do exactly what you describe over time.

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my money is on it's a bad jack.  if you aren't on the tip then you won't get signal at all (assuming the plug is pushed in all the way).  just use your multimeter and test that your live is going to tip to rule that out (as suggested by curtisa).  those jacks are notorious (specifically the cheap versions) for the prongs loosing their integrity.  they are really pretty small and delicate mechanical connections.  

btw and for the record... I can't prove it but I am almost certain I have had barrel jacks like this that did NOT follow the convention based on lug length.  If memory serves me this thru me for a loop at one point - but again... easy to test.

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@curtisa @mistermikev @Bizman62

 

well.

 

it was both :)

 

it was the wrong lug, even though it worked fine?

 

but wired up correctly, it still wiggles, and the cut out is arguably worse than before.

 

with the jack fully out, the hot lug actually giggles a mm itself, likely the cause (or contributing) .

 

so new jack on the way. Thanks peoples 

 

cc

 

 

 

 

 

 

 

 

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17 minutes ago, CC1 said:

it was the wrong lug, even though it worked fine?

There's three connectors as shown in my sketch above. When the hot wired connector touches the tip of the jack and the grounded one the sleeve, there's a working connection. Even the two "hot" lugs would work that way when the plug is pushed to the bottom. But when the sleeve touches both connectors there's a short circuit (the grey plug).

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4 hours ago, Bizman62 said:

Even the two "hot" lugs would work that way when the plug is pushed to the bottom.

It's not clear that the original miswiring of the socket was by switching the tip and ring connections, but both hot lugs cannot simultaneously make contact with the tip of the plug if you pushed it all the way to the bottom of the socket (discounting the possibility that the socket is so completely faulty inside that all sorts of misaligment is going on under the hood to make it totally useless). @CC1's first photo shows his test plug fully inserted into the socket.

What's more likely is that the original miswire was swapping the ground on the ring and sleeve terminals on the socket. Electrically it would be identical if you inserted a mono plug - the sleeve of the plug would make contact with the ring wiper inside the socket and the plug would get grounded as it should; the contact point of this ground would just be closer to the tip on the plug. Swapping the ground on the sleeve and ring connections back to the correct terminations changes nothing electrically, as the sleeve on the plug still gets connected to a ground once inside the socket (just further away this time around).

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11 hours ago, curtisa said:

both hot lugs cannot simultaneously make contact with the tip of the plug if you pushed it all the way to the bottom of the socket

No, and I was not trying to tell that would be possible. I meant the other hot lug in a stereo jack could be wired as the ground when a mono plug is used as it would touch the sleeve of the plug. Not something you'd recommend but definitely doable. Just as you described in the last paragraph.

That said, a poorly made jack is a possible culprit as well. I've witnessed the open type mono jacks struggle with getting the tip hooked. That wouldn't be visible in a closed jack.

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