Get connections between tip and ground

Started by Bigshredder, March 01, 2021, 12:53:44 PM

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Bigshredder

Hi 🙂
I have tested my diy pedals and I often get some connections between the tip and ring/ground on my input jacks but not on the output jacks on the kits that I build. The reading is not 0.0 on my multimeter but it has some connections. Is this normal that ground and tip is connected on the input? They sound great but I started to check every pedal after I got grounding issues with a blend pedal I built and that is whey I noticed it.
Thanks 🙂

davidh

hi!
i guess you mean tip/sleeve? could that be?
since you wrote the pedals sound great, i guess everything is ok, and then i guess the input is only grounded when nothing is plugged in the input.

it is good practice to ground the input of a pedal when nothing is plugged in (this is simply done with a input jack with a switch, on the switch you have ground connectet to tip, when a cable is plugged in this connection is removed and replaced with the signal going in). otherwise you can have a lot of noise coming from the pedal (especially when some highgain circuit), when it is pluged into an amp, turned on BUT input left empty.

not shure if this was your question... just my thoughts after reading.

Bigshredder

Hi,
I mean ground because it gets different readings between 111.0 - 40.0 on my multimeter with the red indicator on the tip on the jack and the other on the enclosure.

antonis

"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Bigshredder

Well, if the connection is good it should be 0.0 so this might mean that something is not quite right or is this natural that there is som "bleed" on the tip of the jack?
On another forum one guy asked me what the exact number was on my reading.

ElectricDruid

Quote from: antonis on March 01, 2021, 03:06:05 PM
Numbers without units say nothing.. :icon_wink:

Maybe it's in radians!

More seriously, I agree with Antonis. What is being measured in this situation? Are you measuring resistance between these points? Do you have the power off? What range is the meter set to?
Without knowing these facts, the numbers alone don't have enough context to mean much.

antonis

Quote from: Bigshredder on March 01, 2021, 03:26:34 PM
On another forum one guy asked me what the exact number was on my reading.

Really, did he..??  :icon_wink:

P.S.
Do you refer on resistance, voltage or current measurement..??
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Bigshredder

I just put my multimeter on 200k ohm and have the red cable vohmmA and black on COM. My dad told me to have i like that a few years ago but I am novice in electronics. But I guess it means resistance right?

antonis

Quote from: Bigshredder on March 01, 2021, 03:40:26 PM
I just put my multimeter on 200k ohm and have the red cable vohmmA and black on COM. My dad told me to have i like that a few years ago but I am novice in electronics. But I guess it means resistance right?

Right.. :icon_wink:
But 111k to 40k (on 200k range), actually denotes a discharging cap..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Bigshredder

Ok, thanks for the tip. What would you do in this case? Try to find the bad cap and changed it?

anotherjim

Your body has some resistance so make sure your fingers are not touching the meter probe tips.

Many effects have a resistor fitted between tip and sleeve contacts. This is generally a large value, 1M ohm or more. Your meter shouldn't show it on a 200k ohm range, but if you are touching the probes, your body resistance is connecting to that resistor and lowering the total resistance which could bring it into the meters test range.

As mentioned, there will be a capacitor connected to the input of the circuit. This takes time to charge up. Your meter uses some voltage to measure resistance which will cause a charge to build up in the capacitor. While it is charging, it will show as some resistance. It will be a low resistance reading to start but slowly increasing. It should increase until out of range of the meter scale.

Try reversing the meter leads and see what happens. Any capacitor will discharge or charge as you swap the probes over.
Try testing any odd capacitors you have and look for the same effect. Large value capacitors in the uF ranges are more obvious. Small values in the nF and pF charge or discharge too fast to see.