No sound from Nobelium

[vigilante398]

I would highly recommend putting one together as they can be an incredibly useful tool if you don't have access to things like an oscilloscope. There are loads of guides and instructions on the internet like this.

If you're confident in the soldering and offboard wiring and the voltages are what they should be, you will learn a lot more about where the problem is from audio probing than you will from anything else.

 

[itchymusic]

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

Alright seems I can build one quite easily.
I'll do that and redo the tests - right after cooking dinner for the fam.
Thanks for getting me on track again!

 

[itchymusic]

I would highly recommend putting one together as they can be an incredibly useful tool if you don't have access to things like an oscilloscope. There are loads of guides and instructions on the internet like this.

If you're confident in the soldering and offboard wiring and the voltages are what they should be, you will learn a lot more about where the problem is from audio probing than you will from anything else.

Yes I just discovered this! Always thought an oscilloscope was the only tool... Great

 

[itchymusic]

I would highly recommend putting one together as they can be an incredibly useful tool if you don't have access to things like an oscilloscope. There are loads of guides and instructions on the internet like this.

If you're confident in the soldering and offboard wiring and the voltages are what they should be, you will learn a lot more about where the problem is from audio probing than you will from anything else.

Now I've built the probe and listened. I got music on both sides of R14 right into the tube socket pin. The rest of the places you asked me to probe only hum.

 

[vigilante398]

Now I've built the probe and listened. I got music on both sides of R14 right into the tube socket pin. The rest of the places you asked me to probe only hum.

Okay, that means you're not getting any amplification going on at V1, so you'll want to start reflowing and checking connections around there.

Debugging is a tedious process, but it's worth it eventually.

 

[itchymusic]

Okay, that means you're not getting any amplification going on at V1, so you'll want to start reflowing and checking connections around there.

Debugging is a tedious process, but it's worth it eventually.

Ok now I've reflowed everything around V1 including R15. I've measured values of all resistors and checked for continuity as many places as possible. I really can't find anything wrong.
Some observations:
Is it right that the two rightmost connecting pins are shorted (top and bottom closest to V2 board)? I get continuity there. And they both measure 1000k to ground.
There's a lot of other resistances to ground which may or may not be of help. I'll upload a picture:

 

[itchymusic]

As I've been over all the components and the soldering around V1 multiple times, I'm starting to wonder if I could have broken a trace on the board somewhere... Or is that a completely unlikely scenario?
Does these resistance measurings help at all? And if so, would someone with a working unit be so kind as to give me their numbers for comparison?
Thanks

 

[Tassieviking]

Make sure that the pins from the tube sockets cant touch anything on the main PCB, I always trim them right down and also the pin header pins.
Cut off the excess leads from the solder side if you can.
I think some of the tube socket pins can scratch on the main PCB if you don't trim them down after soldering them.
R14 goes to pin 7 of the V1 tube and the output comes from pin 6 on the V1 tube and goes to R13 / C6
I did a trace of my Nobelium PCB and redrew the circuit for myself for the fun of it and it might make it easier to trace any faults for you.
I did TBV2 wrong as I used a right side daughter board but it should be a left one like TBV1. (Pin Header to Tube PCB)
On my schematic TBV1 is the pin-header layout as you see it from the top of the main PCB.
Here is my schematic version:

 

[itchymusic]

Thanks a lot! That's very helpful.
I actually did the opposite, where I looked at the build guide and saw a left and a right board, while only having to left boards. I thought they had packed the wrong board for me, as there were some other mistakes in the kit I got, and decided to just solder it upside down like yours... Ouch that was a time consuming mistake, de soldering the tube socket and connector pins

 

[Tassieviking]

If you have to desolder daughter board it is best to cut all the pins first so you can desolder them one at a time, you just have to replace the pin header.
It is very hard to desolder anything with multiple pins without damaging the PCB tracks.

 

[itchymusic]

If you have to desolder daughter board it is best to cut all the pins first so you can desolder them one at a time, you just have to replace the pin header.
It is very hard to desolder anything with multiple pins without damaging the PCB tracks.

Oh, maybe that's what happened then. It was super hard to desolder and remove the connecting pins... Hmmm if so, I would still be able to fix it with a wire, IF I'm able to locate the broken trace

 

[Tassieviking]

Did you draw the numbers on your drawing back to front on your resistance measurements ?
You have 1k5 between the input to pin 3 on V1, that should be on pin 7 on V1, run the numbers in the opposite direction and see if it makes sense.
The pin you marked as No4 is actually number 6 on the socket and it seems not connected, it should go to R9, R13, C6.
This looks like a problem to me, check it out with your multimeter from the tube socket to R9 Bottom.
I marked V1 pin 6 on the main PCB with yellow between R9 and the pin header.
Edit: Next time you order a C2CE PCB order at least one of each daughter board to keep as spares, I did that because they are cheap and it saves ordering just the one you might damage in your build.

 

[itchymusic]

Wow, that's it!
I was away over the weekend and just got back to this, looking at the advice I got from Tassieviking.

No problem numbering the socket pins the other way around the clock and even with yet another careful reflow at pin 6, the corresponding connector pin and R9 I couldn't get a reading on the meter. So I must assume a broken trace from all the yanking when I de soldered the tube socket and pin connector.
I've now connected socket pin 6 to the connector pin (3 I would call it) - good thing I hadn't cut it all the way down yet... And there is music! Both XLR and 1/4" have output and it sounds good and healthy.

I'm very grateful for your help. Thanks so much for looking at this and pinning down my issue.

I haven't closed the box yet though as I discovered another weird thing:
While playing bass through it, every once in a while the bass sound drops out to be replaced by a loud hum. At first I thought it was a bad cable or sketchy soldering at the input jack, as fiddling around the input seemed to cure it. But it doesn't really react to the mechanics of manipulating it. It's more like the sudden loud pop of me shorting the input "wakes it up". So I tried touching the input on the board with a multimeter probe while the hum was on, careful enough as to avoid any moving or twisting of wires. This seems to consistently bring it back from the hum state to clean music signal.
Any ideas what could cause this behavior? Bad cap?

 

[itchymusic]

Oy, found the issue in a cable outside the pedal woops
So now it's all boxed up and playing. And I love how it sounds and feels.
I have a few tube amps that I switch between depending on music and venue - most commonly a Fender Dual Showman, a Fender Studio Bass and an Ampeg PF-50T. No surprise, the Nobelium sounds and feels very close to the two Fenders. A bit cleaner than the Showman and a bit faster than the Studio Bass. With the low cut/bass boost setting it can approach some of the sounds from my PF-50T, but with less compression on the attack and less inherent saturation.
This is all just from playing through headphones so I'm really looking forward to testing it through an amp. And also with my double bass, where the 10MOhm input impedance should really make a difference for the piezo.

 

[vigilante398]

No surprise, the Nobelium sounds and feels very close to the two Fenders. A bit cleaner than the Showman and a bit faster than the Studio Bass. With the low cut/bass boost setting it can approach some of the sounds from my PF-50T, but with less compression on the attack and less inherent saturation.
This is all just from playing through headphones so I'm really looking forward to testing it through an amp. And also with my double bass, where the 10MOhm input impedance should really make a difference for the piezo.

I always get irrationally upset when people say the Noble is like a B-15 in a box, it has far more in common with a Fender design than an Ampeg design. Glad you were able to get it figured out, and as always a big thanks to @Tassieviking who is becoming our resident subject matter expert on C2CE.