intermittent sound coming out of guitar

finest1

hi all

i've got a mexican strat ive modded.  I replaced the pickups with a set of Dimarzio single coils.

the thing thats annoying is when i plug the guitar in, the sound is really low. when i play it it sounds tinny and distant. when i knock the scratchplate you get a jolt and and the guitar comes to life for a few seconds then fades out again.
today i double checked all the wiring and even changed the 5 way switch.....still the same.  all grounds are fine. i honestly thought it would work this time. its flipping annoying!!!

previous to the replacement the guitar pickups were working fine

any ideas?

thanks

sweepy

Sounds like a dry joint tbh

ICBM

Sounds like a bad connection, or a faulty volume pot - overheating the pot when you solder the pickup ground wires on can do that.

finest1

dry joint?

bad connection?

are you talking about the actual soldering? because i resoldered everything to the new 5 way switch. i haven't soldered anything to the volume pot, unless the pot all of a sudden became faulty

anything else i can try?

ICBM

finest1 said:

are you talking about the actual soldering? because i resoldered everything to the new 5 way switch. i haven't soldered anything to the volume pot

Where did you solder the pickup ground wires to?

FelineGuitars

Lack of earth wire from pot to pot maybe relying on foil on pick guard to provide earth?

finest1

@ICBM  ground wires to the back of the volume and tone pots. 

@FelineGuitars i kept the same wiring on the pots, all I did is change the pickups. I made sure the ground wire from pickups went to either a volume or tone pot. 

 The pickups are the virtual vintage series from the dimarzio if that helps

thanks
 

ICBM

finest1 said:

@ICBM  ground wires to the back of the volume and tone pots.

So there's a possibility you overheated the pot and damaged it. It's not that difficult to do.

Does the ground wire to the jack also go to the volume pot, or to a tone pot? Ideally you want all the ground connections on the volume pot.

Headphones

One of the distinct things a bout a guitar is that, when you strike a string, it starts loud, then gets quieter...

On a more serious note, check that nothing unintentional is on, or close to, the screening foil/metal parts.  Particularly check for whiskers - and I don't mean feed the cat!

finest1

@ICBM no, term claw ground and input jack ground is on the back of a tone pot.  Pickup grounds are shared amongst volume and tone. I didn't want to overload the volume with solder and heat. In fact I've hardly heated the volume pot.

finest1

@Headphones  yes I checked when I installed the 5 way switch

ICBM

finest1 said:

@ICBM no, term claw ground and input jack ground is on the back of a tone pot.  Pickup grounds are shared amongst volume and tone. I didn't want to overload the volume with solder and heat. In fact I've hardly heated the volume pot.

Are the volume and tone pots also linked by a wire, or does the ground go via the foil shielding as FelineGuitars asked? If so that's a major possibility for where the problem is. If so, move the output jack ground to the volume pot (best) or solder a wire between the two. The trem claw ground doesn't matter as much.

If the switch is fine then the problem must be between it and the output jack, so there is definitely a bad connection somewhere around the volume pot, and if the sound goes thin and weak it's more likely to be in the ground - an open circuit in the hot just gives silence.

finest1

 Thanks I will give this a try on the weekend. Common consensus says I should ground on the volume pot, I thought pots were the same. The reason  I grounded on the tone
 pot is because the output jack ground was short but I will double check on the weekend. Do you think I should ground all the pick ups  to the back of the volume up too?

ICBM

finest1 said:

 Thanks I will give this a try on the weekend. Common consensus says I should ground on the volume pot, I thought pots were the same. The reason  I grounded on the tone
 pot is because the output jack ground was short but I will double check on the weekend. Do you think I should ground all the pick ups  to the back of the volume up too?

If possible and you can do it without overheating the pot, yes - it's always best to bring all the grounds to one point if you can - this is called 'star grounding' and minimises hum. On a single-volume-control guitar it should always be the volume pot, since that's the source of the signal the amp sees, again to minimise noise.

If the output jack wire is too short to reach beyond the tone pot, you could connect the pot casings together with a wire to ensure a good ground connection - although in theory this could cause a ground loop if they're also making contact via the foil, it's the lesser of the two problems if the guitar isn't working properly! This is common on old Teles, Jazz basses etc when the control plate gets a bit rusted.

finest1

Couldn't I just extend the output ground wire?

ICBM

finest1 said:

Couldn't I just extend the output ground wire?

If you want! Although by soldering a wire between the volume and tone pots you're effectively doing exactly that.

finest1

you mean like this

https://ibb.co/eCQ2Va


 

ICBM

finest1 said:

you mean like this

https://ibb.co/eCQ2Va

Yes, exactly.