GGG Tube driver.... help please!!!

[Lenno]

Hi, I am new here.
My name is Len David and I live in the Netherlands.
I built the tube driver from GGG but it´s not working.
The 12AX7 does light up. I read another topic about someone who didn´t get a negative voltage on the V-.
I think this is my problem aswell.
These are the voltages measured from ground on the IC and on the Tubepins:

IC
1. 9.42V
2. 9.42V
3. 0.20V
4. 0.17V
5. 0V
6. 9.08V
7. 9.42V
8. 9.97V

tube:
1. 8.16V
2. 0.02V
3. 0.17V
4. 12.36V
5. 0V
6. 9.55V
7. 0.04V
8. 0.17V
9. 6.10V (not connected)

There are no negative voltages..
I checked the orientation of all capacitors and diodes, and they are ok. There is no sound at all, when hooked up to an amp.
What could be the problem???
Thanks,
Len

[GibsonGM]

Hi Len,
Welcome!   It's helpful if you include a link right to the schematic you used, so someone can jump right there to see it!  And also, are you using their PCB, or doing your own, point to point, etc?   Try using an audio probe (search forum for how to make one) and isolating where the problem occurs....once you've got the output from the IC, you can then figure out what's up with the tube. 
Could be a short on some of the opamp pins...check them carefully!   Pins 2, 3, and 6, 7 seem very high!!  I think there is a solder bridge across IC pins...
Good luck, you'll get it working, just be patient )

[Lenno]

thanks for the reply
The schematic I used is from the ggg site: http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=83&Itemid=26
I used the pcb layout on the site, but made my own.
I've never done troubleshooting on one of my projects so this is all new to me.
I will check the opamp pins. 

[the_random_hero]

I would almost put any money on there being an issue with D3, R20, C13 or C14. Double check the polarity of the diode and make sure R20 is the right value. You should be getting around the -9V range on pin 4 of IC1 and pin 3 and 8 of your tube.
Apart from that, there's a few voltages off. As far as I'm aware, you shouldn't be getting +V on pins 1, 2, 6 and 7 of the op-amp (I'm very sure of pins 6 and 7, there's two caps in the way from any DC supply).

[Lenno]

R20 is the right value (1K) c13 and 14 are both connected with + to ground. D3 has the right polarity and measures 0,17V on one side and 12.39V on the other side

[Nashtir]

you should use a 12,6v AC, if you are using a dc that's why it doesn't work!

[Lenno]

Are you sure? On this layout it says a 12.6V DC transformer or jack: http://www.generalguitargadgets.com/diagrams/tube_driver_lo.gif
If I'm not mistaken the indicator leds wouldn't work on AC this way...

[the_random_hero]

you should use a 12,6v AC, if you are using a dc that's why it doesn't work!

Oh crap, he's definitely correct there. I should have spotted that one straight off! If you check on the schematic, it's got a step-down transformer straight onto the filaments then the diodes. With DC, D3 is going to be blocking any negative voltages as it's reverse-biased.

[Lenno]

I bought a 12V AC power supply yesterday, and the V- is now -1.5V I will post exact voltages shortly. There is still no sound.  I used an audio probe and the I can follow the signal to the ic. But on pin 7 of the ic the signal is a lot more weak and the peaks are clipping. on pin 7 of the tube socket the signal is very weak and pin 1 has almost no signal left. If I plug in the guitar there is no sound at all.
I don't know what to do next....

I have another question about the wiring to the pots. On the layout, are the pots viewed from the bottom or the top?

[Lenno]

I just remeasured all the voltages with the 12V AC power supply

IC:

1. 0.04V
2. 0.04V
3. 0.02V
4. -1.44V
5. 0V
6. 0V
7. 0V
8. 11.0V

tube:

1. 9.9V
2. -1.49V
3. -1.44V
4. 13Vac
5. 0V
6. 4.9V
7. -3.9V
8. -1.44V
9. 6.4Vac (not connected)

Does anybody have an idea what could be wrong?

[Lenno]

I thought i'd measure again to double check, but the voltages are different! I don't know how this is possible.
now it's this:

IC:

1. 0.02V
2. 0.02V
3. 0.01V
4. -3.79V
5. 0V
6. -1.59V
7. -2.37V
8. 11.0V

tube:

1. 7.88V
2. -3.86V
3. -3.78V
4. 13Vac
5. 0V
6. 4.31V
7. -3.9V
8. -3.78V
9. 6.4Vac (not connected)

[frankclarke]

Stick with the Audio Probe. If the opamp isn't making the signal louder, you have wired it up wrong.