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massive humming on module
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author massive humming on module
benniii
dear all,
just got a DIY toppobrillo triple wave folder second hand. connected it in my rack and can't get much more than a massive humming from it. yet, the humming becomes a little less when i touch the panel of the module (or any other panel in my rack, as a matter of fact).

starting to wonder: is something wrong with my power supply? everything else has always seemed to work very fine!

(or, as a matter of fact: anybody any clue what could be the issue with this particular module?)

thanks!
mirth23
Try unplugging some of your other modules to rule out the possibility that adding the new module didn't exceed the capacity of your power supply.
alanza
My Ladik preamp is currently (naïvely) on the far edge of my case right near where the power supply plug is, and so it picks up a low frequency hum from that at medium gain. Could something like that be causing the problem?
benniii
mh.. i'd rule out the lack of power, tbh ... my rack is at around 4A and i have a trogotronic m15 which should provide me with 10A if i'm not mistaking.

moving the topobrillo somewhere else didn't fix the issue, either... actually took it out of the rack completely (while being powered) – no difference /:

thanks anyways for your help
Bitmud
Hi,
sound like a missing ground (GND) connection to the module.
If you are lucky, it is only the cable.
Change the cable and check the red line. Red line to -12 V!

If you have a muti meter (or ohm meter) you can check the bus connections from the pins for the cable (-12 V, GND, 5 V, 12 V) to the first parts or pads on the PCB (printed circuit board) maybe the connector is wrong or the soldering is not done well.
Disconnect the module first from the bus power.

You can see the bus connection on the Doepfer page, or...




good luck!
benniii
hei bitmud,
thanks a ton! ... ok, so.. i've checked what you said – i'd be gracious if you try to follow me:

1) i've set my voltmeter to beep when there's a connection (:)), and from the GND-pin on the connector, i've started touching multiple spots on the board that are said to be GND in toppobrillo's schematic . they all seem to "work" (as the voltmeter beeped)

2) .. yet, there's one weird thing that i'm noticing (knowing nothing about electronics): when i touch GND and -12/12v, i get a very, very short beep... my voltmeter states there's a resistance of ~14k ohm. shouldn't there be no connection at all (as this states that -12/12 and gnd are connected)? or is this normal, per se?

edit 3) also, none of the output-connectors/jacks on the module are connected to ground... is that normal?!

beyond that, i'm kind of lost /:
pre55ure
benniii wrote:
hei bitmud,
thanks a ton! ... ok, so.. i've checked what you said – i'd be gracious if you try to follow me:

2) .. yet, there's one weird thing that i'm noticing (knowing nothing about electronics): when i touch GND and -12/12v, i get a very, very short beep... my voltmeter states there's a resistance of ~14k ohm. shouldn't there be no connection at all (as this states that -12/12 and gnd are connected)? or is this normal, per se?

edit 3) also, none of the output-connectors/jacks on the module are connected to ground... is that normal?!

beyond that, i'm kind of lost /:


I would agree (with Bitmud) that it sounds like there is no ground connection.

#2 sounds ok. +/-12 will be connected to ground - but through various components, so 14k seems like a reasonable measure. The short beep is likely because +/-12 is usually connected to ground through capacitors which will pass a very short pulse before they start blocking.

It would be somewhat unusual for the jacks to not be connected to ground, but it's usually the sleeve of the jack which means that it might be hard to tell unless you insert a cable and then test the other side.

If you have another power cable that fits the module, I would just try that. It's much more likely that the problem is in the power cable than it is on the board.
Bitmud
benniii wrote:
hei bitmud,
thanks a ton! ... ok, so.. i've checked what you said – i'd be gracious if you try to follow me:

1) i've set my voltmeter to beep when there's a connection (smile), and from the GND-pin on the connector, i've started touching multiple spots on the board that are said to be GND in toppobrillo's schematic . they all seem to "work" (as the voltmeter beeped)

2) .. yet, there's one weird thing that i'm noticing (knowing nothing about electronics): when i touch GND and -12/12v, i get a very, very short beep... my voltmeter states there's a resistance of ~14k ohm. shouldn't there be no connection at all (as this states that -12/12 and gnd are connected)? or is this normal, per se?

edit 3) also, none of the output-connectors/jacks on the module are connected to ground... is that normal?!

beyond that, i'm kind of lost /:


1) okay. GND connection is okay. If you have a volt meter you can check +12 V and -12 V on the board, too. You have to be carefully do not short-circuit the component.
One cable (e. g. black) to GND of the board and the other one to the 12 V pads for the measurement.

2) It's normal. You "beep" input has a diode. If voltage detected they made a short beep. If there is a stable resistor (e. g. 14 kOhm) to measure everything is fine.

3) hm, panel and one pin of the jacks and potentiometers should connected to GND. Is there a connection from the panel (blank metal spot) to the analogue GND pin of the connector?

Everything should be on the same potential or in other words - should have one ground.
benniii
ahw thanks SO much for taking the time, pre55sure + bitmud.

as for power: i've tested to cables – same problem /: but! -->

[quote="pre55ure"]
benniii wrote:
hei bitmud,
It would be somewhat unusual for the jacks to not be connected to ground, but it's usually the sleeve of the jack which means that it might be hard to tell unless you insert a cable and then test the other side.


ok, i've connected a cable to one of the outputs and checked for a connection between its ring and the ground-pins (on the power-connector of the module)... no beep! ... does that make sense? is this the way it should be?
pre55ure
benniii wrote:


ok, i've connected a cable to one of the outputs and checked for a connection between its ring and the ground-pins (on the power-connector of the module)... no beep! ... does that make sense? is this the way it should be?


The jack sleeve is usually connected to ground, so that is unusual. However it is not strictly necessary unless you are patching from that output/input to a system on a different power supply. (Synths that use banana cables don't have a ground connection on the banana jacks). Are you using the TWF as the final output before your signal goes to a mixer or speaker? If so this could be the problem, but if you have the loud "humming" when connected to other modules within the same system (connected to the same power supply) then the jack ground connection isn't the problem.

However, the fact that the humming is reduced when you touch the module, really makes it sound like the module ground and the system ground are not connected somehow.
Bitmud
[quote="benniii"]ahw thanks SO much for taking the time, pre55sure + bitmud.

as for power: i've tested to cables – same problem /: but! -->

pre55ure wrote:
benniii wrote:
hei bitmud,
It would be somewhat unusual for the jacks to not be connected to ground, but it's usually the sleeve of the jack which means that it might be hard to tell unless you insert a cable and then test the other side.


ok, i've connected a cable to one of the outputs and checked for a connection between its ring and the ground-pins (on the power-connector of the module)... no beep! ... does that make sense? is this the way it should be?


If you checked the output with a cable you should have no beep, because there should be a resistor from signal (tip, hot) to GND (ring, cold).
Can you measure a resistor at all outputs between tip and ring?

The TWF ia a effect module. There is no signal at the output (just humming) at all when you use a signal (e. g. sin) at the input?
Dr. Sketch-n-Etch
Interesting thread. I've gotten that sort of hum in my system when I've failed to connect ground between my modular and another sound source (such as an MP3 player).

Have you tried changing the power cable? Try using one that you know is good. If that doesn't work, then the problem is definitely on the module. It sounds like a broken connection somewhere to me, but ground is typically soldered to at least six pins on the Eurorack power connector, so the chances that ground is not getting to the module at all are pretty slim, unless some real liberties were taken with laying out the power connector.
benniii
thanks again, folks! great to have help! ok, so...

Quote:
The jack sleeve is usually connected to ground, so that is unusual. However it is not strictly necessary unless you are patching from that output/input to a system

the weirdness continues... wonder if anyone can make any sense of this: i do have two racks, but they (...should) run off one same power-supply (trogotronic M15). i've connected these two racks with a ~10inch powercon cable to share -12/12/GND between their busboards.

· in the second rack (that's hooked up via powercon) the module hums like crazy no matter if i've got an input running to it or not.

· in my first rack (that has the trogotronics bricks directly connected) – the module doesn't hum (– yet, it still behaves strange when patching from its outputs.. tends to mute other stuff.. weird).

but: placing the module in the second rack and patching its output to a vca inside this rack and then to the mixer - seems to eliminate the hum. the grounds of both racks are how ever connected; i've checked that with the voltmeter ("beeper").

any clue? :eek:

edit:
Bitmud wrote:

Can you measure a resistor at all outputs between tip and ring?

shall the module be powered to do this?

Dr. Sketch-n-Etch wrote:

Have you tried changing the power cable?

i did try multiple cables.. didn't change anything /:
Bitmud
benniii wrote:
thanks again, folks! great to have help! ok, so...

the weirdness continues... wonder if anyone can make any sense of this: i do have two racks, but they (...should) run off one same power-supply (trogotronic M15). i've connected these two racks with a ~10inch powercon cable to share -12/12/GND between their busboards.

· in the second rack (that's hooked up via powercon) the module hums like crazy no matter if i've got an input running to it or not.

· in my first rack (that has the trogotronics bricks directly connected) – the module doesn't hum (– yet, it still behaves strange when patching from its outputs.. tends to mute other stuff.. weird).

but: placing the module in the second rack and patching its output to a vca inside this rack and then to the mixer - seems to eliminate the hum. the grounds of both racks are how ever connected; i've checked that with the voltmeter ("beeper").


So one module behaviours different on two racks with one shared power supply.
Sounds like an issue with your environment not with the module.
Put the module in the first rack and make a simple patch maybe with a sin source (no modulation). Does it sounds as intended?

If not, don't power the second rack. Maybe there is something wrong.

edit:
Bitmud wrote:

Can you measure a resistor at all outputs between tip and ring?

benniii wrote:
shall the module be powered to do this?


Put the module in your first rack and power on. Use a patch cable at the output, no input. Then measure just at the tip and ring of the patch cable.
If there is no stable resistor value, you have maybe a defect output.
Drakhe
I've had a Topobrilo module that behaved wonky (Quantimator).
I've been able to make it work correct by adding some nylon spacers between the module and the mounting rail and making sure there was no module touching left or right.

On a similar note, I've had a Pico DSP misbehave. It was to the far right of my case and there was probably something on the module that touched the rail mounting plate on the inside of the case. cover the mounting plate with some tape and now the Pico DSP works fine.
toppobrillo
Drakhe wrote:
I've had a Topobrilo module that behaved wonky .


can you elaborate?

Quote:
just got a DIY toppobrillo triple wave folder second hand. connected it in my rack and can't get much more than a massive humming from it.


being a DIY build I don't know what it could be but I could take a look at it for you if you like.
benniii
hei toppobrillo,

thanks so much for jumping in! appreciate that offer a lot! ... as i suppose it'll be quite an effort (for the both of us) to get the module to the states (i'm based in germany), you think we may be able to pin some things down from here?

for starters – can you tell me if it's normal that the outputs of the TWF have no connection to GND at all?


Drakhe wrote:

I've been able to make it work correct by adding some nylon spacers between the module and the mounting rail and making sure there was no module touching left or right..


i think i'd rule this out.. have tried to module without even placing it in my rack and still got his loud humming/buzzing.
benniii
Bitmud wrote:

Put the module in the first rack and make a simple patch maybe with a sin source (no modulation). Does it sounds as intended?


that's the only way i get it to work (or am i missunderstanding you?). the module does what it should in my first rack – in the second however (running off of the same powersupply), it hums. i have made sure that GND is shared in both racks and as i said – everything else works fine /:

Bitmud wrote:

Put the module in your first rack and power on. Use a patch cable at the output, no input. Then measure just at the tip and ring of the patch cable.
If there is no stable resistor value, you have maybe a defect output.

resistance is stable (voltmeter sais "1" on all outputs:))
Bitmud
benniii wrote:
Bitmud wrote:

Put the module in the first rack and make a simple patch maybe with a sin source (no modulation). Does it sounds as intended?


that's the only way i get it to work (or am i missunderstanding you?). the module does what it should in my first rack – in the second however (running off of the same powersupply), it hums. i have made sure that GND is shared in both racks and as i said – everything else works fine /:


Okay, I see. I guess the difference must be the power supply for the second rack and the GND pins of the module.
The module have a 10 pin version 12 V | GND | GND | GND | -12V. Maybe the connection on the module used just one GND and the power bus doesn't deliver the GND path to this connector.
I hope you can understand this thought.

You can check first again the 3 GND connectors (pins) on the module to a spot (pad) of the module labelled as GND. All 3 pins should make a beep.

I don't have this module and no clue of your setup, this makes it a bit difficult to find the error.
benniii wrote:

Bitmud wrote:

Put the module in your first rack and power on. Use a patch cable at the output, no input. Then measure just at the tip and ring of the patch cable.
If there is no stable resistor value, you have maybe a defect output.

resistance is stable (voltmeter sais "1" on all outputs:))


hihi Okay, no problem. Buy yourself a multimeter (5 - 20 $ / €), if one crosses the way.
Navs
I don't know if this helps or confuses but I've only had a loud hum/buzz from my system for two reasons: one, plugging in a module incorrectly, i.e. flipped the negative and positive rails, and two: an incorrectly crimped power cable.

If you have checked/changed the cable, as Bitmud suggests, can you check the power pins/connector on the module itself to make sure there is not a short there?
Graham Hinton
You are looking at this the wrong way, looking at details without looking at the big picture first.

benniii wrote:

the weirdness continues... wonder if anyone can make any sense of this: i do have two racks, but they (...should) run off one same power-supply (trogotronic M15). i've connected these two racks with a ~10inch powercon cable to share -12/12/GND between their busboards.


A PowerCon is a Neutrik mains connector. Is that what you are using to connect your cases? There is probably something wrong with this connection, why don't you post some pictures so we can see what is really going on?

Quote:

· in the second rack (that's hooked up via powercon) the module hums like crazy no matter if i've got an input running to it or not.


The module is not humming, you have a hum coming out of whatever your monitoring system is, so what is it and how is that connected?


Quote:

· in my first rack (that has the trogotronics bricks directly connected) – the module doesn't hum (– yet, it still behaves strange when patching from its outputs.. tends to mute other stuff.. weird).


That is something that should be addressed before going further. Your lack of a proper description does not help.
How is the other stuff that gets muted connected to anything?

Quote:

but: placing the module in the second rack and patching its output to a vca inside this rack and then to the mixer - seems to eliminate the hum. the grounds of both racks are how ever connected; i've checked that with the voltmeter ("beeper").


A continuity check is not enough because it will beep at a lowish resistance that is still high enough to cause problems.

There is something basically wrong with your first rack, probably incorrect grounding. As you are in Germany, are you using two pin (Schuko) or three pin mains leads (CEE 7/7)? Not just the rack, but all the other equipment it is connected to. Are your mains outlets Earthed?

Did you buy the power system in Germany and is it CE marked (not just the brick)?
Drakhe
toppobrillo wrote:
Drakhe wrote:
I've had a Topobrilo module that behaved wonky .


can you elaborate?



Sure. When I got the Quantimator I first put it in a small lunchbox (kinda toolkit with midi2cv and some multiples) and it worked fine. Then I got the big case (Pitsburgh Modular EP360) where it started to misbehave: either it would be on 'F.' or the chord/scale selection would continuously and randomly change, in either case not responding to the manual select knob.

When I took the module out to check if there was maybe something wrong with the power cable, I noticed the module was probably touching the metal mountingplate for the rails and also that suddenly it was working fine. I put some nylon washers between the faceplate and the mounting rail and made sure the Quantimator didn't touch anything left or right and has been working fine ever since.
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