No sound from Nobelium

[itchymusic]

Hi,
I just finished my Nobelium build (from Musikding in Germany) yesterday. Unfortunately I'm not getting any sound at all. Neither through the di or the amp out.
Both LEDs light up, I can measure ground all the way through, the connection is fine between input jack and in on the PCB. Both tubes heat up as well - no more than they're easy to touch.
The soldering looks quite fine, but does anyone have some indications as to what and where I could measure, as I'd rather try to narrow it down before aimlessly reflowing all the soldering.
Thanks for your help!
PS - i know there's a 12ax7 in V2. I'm still waiting for a new set of ecc82s in the mail.

 

[vigilante398]

Hi,
I just finished my Nobelium build (from Musikding in Germany) yesterday. Unfortunately I'm not getting any sound at all. Neither through the di or the amp out.
Both LEDs light up, I can measure ground all the way through, the connection is fine between input jack and in on the PCB. Both tubes heat up as well - no more than they're easy to touch.
The soldering looks quite fine, but does anyone have some indications as to what and where I could measure, as I'd rather try to narrow it down before aimlessly reflowing all the soldering.
Thanks for your help!
PS - i know there's a 12ax7 in V2. I'm still waiting for a new set of ecc82s in the mail.

Looks like your signal and ground wires are swapped on the 1/4" output jack.

What power supply are you using with the pedal? Are these known good tubes?

 

[itchymusic]

Looks like your signal and ground wires are swapped on the 1/4" output jack.

What power supply are you using with the pedal? Are these known good tubes?

Thanks for getting back so fast!
The tube in V1 is pulled from a working amp head - ruby tubes ecc82s. The other one I'm less sure of, as it has been in the spare box for years. Power supply is a Cioks DC7.
I'll check the out Jack wiring as soon as I'm back home, but have mainly been looking at the XLR out - as that tube is known to be good.

 

[itchymusic]

Ok, so I actually did invert the wires on the out Jack. Oh my... That'll teach me, being all fancy with a yellow wire for signal.
Well, certain things are clearer here as I just dimed the volume, treble and bass:

There is hiss and hum noise on the jack out. It gets louder when I turn the volume up and almost disappears when I turn it down.
The tone controls affect the sound of the noise as you would expect.
I can introduce louder 50 hz hum by moving my hand around over the board with the backplate off so there's no shielding. If I touch the chassis to ground it the 50 hz disappears.
It was harder to hear on the XLR - probably due to the lower volume - but I can get a good 50 hz hum on that one too by touching the wire coming in to the di board closest to the trafo. And stop it by touching the chassis.
Are there any indicators here?

 

[itchymusic]

Oh and I've seen people talking about the MOSFET heating up. Mine gets warm too, but no more than the tubes, so I can easily touch the metal.

 

[itchymusic]

So since I can amplify the hum with the volume control, the tone controls work and I can create hum on the di out by touching wires, I'm assuming the problem is between the input and V2. Most likely on the V1 daughter board. Does that sound right? And again, are there any good points for measuring voltage or continuity here?

 

[74hc]

Why the 1/2 watt resistor in R5?

All of the resistor footprints are 1/4 watt on my boards which is what the BOM specifies. Check R5 and make sure it was not damaged trying to fit it in. If you are comfortable, check your 250VDC supply.

 

[itchymusic]

Why the 1/2 watt resistor in R5?

All of the resistor footprints are 1/4 watt on my boards which is what the BOM specifies. Check R5 and make sure it was not damaged trying to fit it in. If you are comfortable, check your 250VDC supply.

Thanks for the reply.
I got all the components in a kit from Musikding, so maybe it's just whatever they had at hand. I did notice and wonder why, but took care to pre-bend the legs before installing, so there's no damage or stress there.
What do you mean with check the 250VDC supply? Checking the voltage after the pump?

 

[itchymusic]

Ok,
I have now checked the voltage to be 250V at C1.
I have checked all solder joints on the tube daughter board at V1 - and measured that I have continuity from every socket pin, through the board connectors to where they reach the next component in the circuit. Two socket pins seem connected through a common board pin, but that is the same for both tubes daughter boards, so I assume that's the way it should be.
I've built a bunch of other stuff before, but this is my first time building anything with a PS and tubes in it, so I go about it quite carefully...
Does anyone have any pointers? Anything you would like to have measured or see pictures from?
Thanks

 

[itchymusic]

So, I got my new Ecc82 tubes today and fired up this project again.

I'm a little puzzled by the lack of response to this thread. Please tell me if I'm phrasing my question wrongly, giving too little information or seem unwilling/unable to do the testing needed - though I've been a reader for years, this is my first time posting about an issue on this forum.

Anyways, the new tubes didn't help. Only change was less gain, which should be obvious, as I swapped a 12ax7 for an Ecc82.
I've tried carefully probing around with the power on, to see if I could figure where the amplification takes place and where the signal is broken. Shorting at the input only results in a little static crackling, like when grounding. Some of the legs of the V1 tube give loud pops when touched. So does three of the board connecting pins (1, 2 and 7 I'd call them) and the output of R9 and R10. The rest of the components on the V1 side only gives static crackle when touched with the metal probe.

Hoping for someone to look into this as I'm out of ideas. And sorry again if I'm somehow communicating badly.

 

[vigilante398]

Well it sounds like you've checked just about everything I would tell you to off the bat. If you're using known good tubes then that should remove that variable, and a DC7 is one of the best power supplies out there, so you're good there. If you have high voltage measured then you know the SMPS is working.

Checking solder joints is always something I tell people to do, and it sounds like you've done that. Obviously double checking all your cables, amplifier/interface, etc. is a good idea, I've had people send in units for repair because they didn't realize they had a bad cable.

Probing the tube pins isn't as useful as one might expect, but there are a couple spots it could be useful to check on the board:

• Either end of R14 - should be audible, obviously one side louder than the other
• Pin 2 of the treble pot - should be louder than input from R14
• Either end of R15 - should have decent signal on both sides
• Pin 3 of the volume pot - should be pretty loud

If you have audio in all of those places then you should be good to go as pin 3 of the volume pot is where the XLR output taps off from. If you have signal in all of those places but still no output on the 1/4" then something is wrong with V2, and if you still have nothing on the XLR then something has to be wrong with the transformer or the XLR jack itself.

After all that I'm afraid the only other thing to do is the tedious job of checking every single component to make sure it's the right value. This is a verified design that has been built a couple hundred times, but there is a lot going on and a lot of places where things can go wrong.

 

[itchymusic]

Thanks!
I have absolutely no doubts about the design. Bought it after reading tons of great reviews and build reports.
While probing I'm checking with headphones connected to a headphone amp getting signal from the 1/4" out. I'll start checking the stuff you mentioned right away!

 

[itchymusic]

Either end of R14 - should be audible, obviously one side louder than the other
Not really getting anything there

Pin 2 of the treble pot - should be louder than input from R14
Yes plenty loud - all three pins are

Either end of R15 - should have decent signal on both sides
Yes plenty loud

Pin 3 of the volume pot - should be pretty loud
Loud as well, both pin 2 and 3, though not nearly as loud as the volume pot

So is the problem around R14? It reads 1.5k when checking with the multimeter

 

[vigilante398]

Either end of R14 - should be audible, obviously one side louder than the other
Not really getting anything there

Pin 2 of the treble pot - should be louder than input from R14
Yes plenty loud - all three pins are

Either end of R15 - should have decent signal on both sides
Yes plenty loud

Pin 3 of the volume pot - should be pretty loud
Loud as well, both pin 2 and 3, though not nearly as loud as the volume pot

So is the problem around R14? It reads 1.5k when checking with the multimeter

Well that's bizarre, R14 is literally the input. If you didn't have anything there then you shouldn't have anything anywhere else, but if you have signal everywhere else then I would expect you to have signal there as well.

So if you have a good signal on pin 3 of the volume pot, that's the last spot before it jumps out to the XLR daughter board so as long as everything is good on the daughter board then you should be good for XLR output. Double check your wiring to that board, then double check your solder joints for everything on that board.

 

[itchymusic]

Well that's bizarre, R14 is literally the input. If you didn't have anything there then you shouldn't have anything anywhere else, but if you have signal everywhere else then I would expect you to have signal there as well.

So if you have a good signal on pin 3 of the volume pot, that's the last spot before it jumps out to the XLR daughter board so as long as everything is good on the daughter board then you should be good for XLR output. Double check your wiring to that board, then double check your solder joints for everything on that board.

Maybe I'm misunderstanding something or not expressing properly what I'm doing.
I've never been able to get any signal through from the input to either output. I'm just hearing amplified noise from within the circuit. So when I touch something within with one probe of my multimeter, I either get slight static crackling (ground noise), a loud pop and or loud hum.

I've now reflowed the soldering around R14 and the connector pins (pin 9 I'd call it). I've measured for continuity through to the corresponding tube socket pin (the third if you go CCW from the gap).
The connection is fine up until that point, and if turned up pretty loud I hear a hum corresponding to what I hear when touching the tip of the input jack. Very much weaker than if touching connecting pin 1, 3 or 6 though.

 

[itchymusic]

Uh, and right now I'm only listening to the jack out

 

[vigilante398]

Either end of R14 - should be audible, obviously one side louder than the other
Not really getting anything there

Pin 2 of the treble pot - should be louder than input from R14
Yes plenty loud - all three pins are

Either end of R15 - should have decent signal on both sides
Yes plenty loud

Pin 3 of the volume pot - should be pretty loud
Loud as well, both pin 2 and 3, though not nearly as loud as the volume pot

So is the problem around R14? It reads 1.5k when checking with the multimeter

Listening to noise doesn't tell us very much about what is actually going on, you need to send an audio signal into the input. Typically when I am doing audio probing I will hook a looper up to the input so it is always sending something that I can listen for at different points to see how the sound is affected at different spots in the circuit.

 

[vigilante398]

Uh, and right now I'm only listening to the jack out

Does this mean you are not using an audio probe?

 

[itchymusic]

Does this mean you are not using an audio probe?

Yes, just a multimeter. And a jack cable from my bass... Sorry if I've been unclear about that

 

[itchymusic]

Listening to noise doesn't tell us very much about what is actually going on, you need to send an audio signal into the input. Typically when I am doing audio probing I will hook a looper up to the input so it is always sending something that I can listen for at different points to see how the sound is affected at different spots in the circuit.

I can hook up a loop, but unfortunately I don't have access to an audio probe :⁠-⁠(