Help Please, multimeter reading confusing around vacuum tube

[Bungusbeefcake]

Hi guys, I'm making up a guitar pedal using the 12AX7A vacuum tube and I'm running a check for voltages and amps going into the tube using the multimeter.

Basically checking the voltages going into terminal 1 shows as around 77V and the current is around 300 uA. This is correct and what its designed for at 110 VDC.

My problem is when I use the multimeter to ascertain the voltage and current going into terminal 6. When I check this its giving me voltage readings of -250V and -10 mA.

I have no idea why its reading the so differently, Could anyone please help me, I've attached my design. Maybe I wired something up backwards or something, but I'm not sure. The analysis of the input and output signal through the circuit seems fine but this multimeter reading baffles me.

Thanks guys.

As a side bit of infor, I'm actually from Ireland so I'll be changing that 110VDC input to 230VDC and want around the same current through the tubes, so I've changed R4 from 330kOhm to 769kOhm and looking to do something similar to R6 to bring the current down there to around the same entering terminal 6. So if you have any advice on that also I'd really appreciate it. 

Bungus

[Justin.]

Hey Bungusbeefcake,

I've taken a look at your schematic and you don't appear to have labelled terminals 1 or 6. Could you please label these and re-upload your schematic?

Also, have you copied this circuit from somewhere or is this your own design?

[Bungusbeefcake]

Justin, 

Thanks for the reply! PLease find attached the edited schematic with Terminals 1 and 6 clearly labelled.

The design isn't my own design, its a design which has been around for over a decade now. I have attached the original schematic too so that you can have a look at that.

I also have other issues with the circuit, but that is really  multisim thing I think. I'm trying to replace the DC voltage with a single 230VAC source and t transformers from that. One transforming 230VAC to 12VAC and the second transformer tranforming the 12VAC back up to 115VAC. I have a rough drawing of what it should actually look like attached too, if you have any ideas how I do that on multisim. I can do individual transformers but none this complicated.

Thanks,

Bungus

[fang0717]

do not confused about this, i will show you how to read this. checking the voltages going into terminal 1 shows as around 77V and the current is around 300 uA. and you can refer to www.analogtechnologies.com for more information.

www.analogti.com