THCustom - Valve Driver 1.2 [Tech help needed]

[Topsy]

Hey guys,

1) Valve Driver V1.2 (kit called Tube Driver on Musikding.de, which is where i bought the kit from)
Build document : http://diy.thcustom.com/?wpdmdl=3217

2 / 3) This is my first project and I bought 2x kits knowing that I'd probably mess it up, the first one i boxed it and everything turns out i had multiple errors. Second attempt I decided to rock it before I box it as recommended and here are the issues :
-First test , audio was running through but only the volume knob was working with a very small range (clock wise only from approx 8 o clock till 11 o clock, beyond that there was no impact on the sound). Other knobs didn't have any impact on the sound.

After further research I realised that I had my IC2 in the wrong orientation, so I bought another one and fixed it.
I set up a small testing rig again, now I have no audio running through at all BUT when I crank my preamp and hear the noise , I can hear that the Bass and Treble knobs are indeed in effect as the noise gets more or less bass-y or treble-y as I twist the knobs .
The 5mm led lights up when I power up the pcb and the tube gets a little warm so the juices are flowing.

4) as far as I know I've used all the correct parts -_-' so no substitutes..etc

I have bought a breadboard and I have a multimeter, but given that I am seriously unexperienced. I am unsure on how to put these to good use in my case. I tried doing a continuity check but my multimeter never beeps with any connection on the pcb (only when the probes touch each other when i test them) which leads me to believe i'm doing it wrong.

I have attached a couple of pictures hoping that someone could point out an obvious mistake I have done : http://imgur.com/a/fkOy2

! Thanks for your patience and tips , I hope I've used the correct format to ask for tech help.

-Topsy

[Topsy]

Update : continuity check is working out , i'm following the circuit and checking each component one step at a time. I will post the findings here !

[WormBoy]

I would not recommend this as a first project: tight PCB, relatively high voltages, and large currents ... I first build dozens of simple pedals before daring to start anything with tubes . So, don't be surprised if it is difficult to get this working properly (and perhaps even impossible with advise-at-a-distance only).

First question: what are you using to power the circuit? This circuit draws 300 mA just to heat up the tube. Did the tube glow (softly) when you tested? What voltages on the tube sockets?

[Topsy]

I would not recommend this as a first project: tight PCB, relatively high voltages, and large currents ... I first build dozens of simple pedals before daring to start anything with tubes . So, don't be surprised if it is difficult to get this working properly (and perhaps even impossible with advise-at-a-distance only).

Hah thanks , that makes me feel better actually ^_^ .

First question: what are you using to power the circuit? This circuit draws 300 mA just to heat up the tube. Did the tube glow (softly) when you tested? What voltages on the tube sockets?

I'm using a TC Electronic power supply that outputs 670mA . Yes the tube glows softly , after reading your post i might have touched the wrong pins while trying to figure out how to check voltage on the tube socket...because the small led died but the tube is still glowing and warming up and my power regulator is still hot so ..

[WormBoy]

I'm using a TC Electronic power supply that outputs 670mA .

That should be plenty.

Yes the tube glows softly , after reading your post i might have touched the wrong pins while trying to figure out how to check voltage on the tube socket...because the small led died but the tube is still glowing and warming up and my power regulator is still hot so ..

That's probably why newbies get the title "diode destroyer" here  . Two of the pins should have some 60V on them (1 and 6, I think) ... sorry it might have been helpful to warn you for that before advising to measure voltages. If the tube is glowing, that means the heaters are getting proper juice, so that is at least a good sign (pin 9 will have some 6V on it).

[Topsy]

Diode destroyer indeed.. well the tube is warm !

[Topsy]

I checked continuity on all the circuit and it all works except for R2 and R3 with each other but it's a bit confusing on the schematics as there is an (opt) note but not sure if it's for Pin 7 to R2 only or maybe R2 and R3 shouldn't be connected . Otherwise it's all good :\

[WormBoy]

And, what about the voltage on pin 1 and 6? Should be some 60 volts if all is well.

[Topsy]

So I set my multimeter to 20V DC(then tried with 200V) metering and placed the probes on pin 1 & 6 , i'm not getting any reading on the metering.

Thanks for staying on top of this Wormboy , appreciate it.

[WormBoy]

So, you put one lead of your DMM on ground and the other to pin 1 of the tube socket, and then pin 6, and result is zero volt? Always fun to try to solve a puzzle like this (if it is not my own build  ).

[Topsy]

Silly of me to test them like I did haha, so on PIN 1 I get 60V and on PIN 6 I get 52V

[WormBoy]

Hmm, looks like the charge pump part is functioning. I am running out of obvious advise here  . From the pictures I don't immediately see a problem (apart from the fact that you need to work on your soldering skills  ). Always good to check the orientation of the electrolytic caps (especially C14), check voltages on the op-amp (IC3, should have 9V on pin 8 and ground on pin 4). If that all checks out, perhaps audio-probing is an option ... (see this link, and also the additional checks mentioned: http://www.diystompboxes.com/pedals/debug.html).

If you get frustrated debugging, buy yourself a simple, more fool-proof kit with step-by-step instructions (from BYOC for example: they make great stuff for starters), and revisit this thing later. This hobby is too much fun to let yourself become frustrated by one build  .

[Topsy]

Thanks for the heads up , I am definitely enjoying the learning experience. Part of the frustration comes that this is part of an experiment I am conducting as part of my final major project with a deadline on the 24th of April >_< . I do love the troubleshooting part though it is what gives me a deeper understanding of what I am doing as opposed to having everything just working out and me not knowing how the f it works hehe. I will do some further testing and work on my soldering skills and post my findings here ! 

[WormBoy]

In that case: audio probing is a great learning experience (with the schematic in hand). I hope you get it working, happy hunting  .

[Topsy]

So with the audio probe I'm getting audio up until PIN 3 on the IC3. no audio on pin 1&2 and the R14 resitor after that is not receiving audio either .

I have two of the same TL072 IC chip and tried both of them ending up with the same result.