Drip EQ1 build wrong voltage

[cameron spinks]

Hi guys,
I have just finished building Drip EQ1 Gen 4.
All the voltages seem to be in the correct range except for the 140v test points.
They read 277v, which seems incredibly high. Double checked all the surrounding resistors and they all looked normal. Anyone have any suggestions?

 

[corgan4321]

solid state or tube rectifier ?

 

[radardoug]

Schematic? Did you use all the correct parts?

 

[rock soderstrom]

Schematic?

That would help since we don't know all the schematics (and their variations) by heart. Are you measuring with or without tubes?

 

[gyraf]

Drip is a commercial operation, charging a premium for the diy-projects: So why not just ask them?

/Jakob E.

 

[cameron spinks]

solid state or tube rectifier ?

Tube rectifier

 

[cameron spinks]

I

Drip is a commercial operation, charging a premium for the diy-projects: So why not just ask them?

/Jakob

Have emailed and no reply so far. He has answered other questions in the past. Thought I'd see of anyone here had run into same problem. Cheers

 

[cameron spinks]

That would help since we don't know all the schematics (and their variations) by heart. Are you measuring with or without tubes?

With tubes. It is very close to the original schematic.

 

[cameron spinks]

Schematic? Did you use all the correct parts?

Yes, I used all the correct parts. All listed on the 2nd pic schematic. No variation.

 

[Rob Flinn]

Hi guys,
I have just finished building Drip EQ1 Gen 4.
All the voltages seem to be in the correct range except for the 140v test points.
They read 277v, which seems incredibly high. Double checked all the surrounding resistors and they all looked normal. Anyone have any suggestions?

You probably have a poor or missing 0v connection somewhere.

 

[cameron spinks]

You probably have a poor or missing 0v connection somewhere.

OK, cheers. I'll do another pass over.

 

[radardoug]

The 140 volt points being high would indicate you are not drawing any current, and so perhaps your tubes are not lighting up?
Easy to see.

 

[dmp]

The 12AX7 cathodes are strange on the EQ1 with the path to ground through the 360R then the tertiary winding on the transformer (yellow-orange) and the center tap (red-violet) to a 1k resistor, to ground. Anything off through all that and the 12AX7 will not be conducting. Problem is probably around the tertiary winding.

 

[cameron spinks]

Thanks to everyone answering in, really appreciate it!

All the tubes are definitely lighting up including the 12ax7.

I have even run audio through it and everything seems to work... which is more puzzling to me.

Will follow dmps suggestion and check that pathway.

Will also do a check for any bad 0v connections.

 

[Admiral-dk]

What voltage du you read from pin 3 & 8 on the 12AX7 ...?.... and for that matter 2 & 7 (the later should only be a few millivolts).

Per

 

[AnalogPackrat]

Have you measured the 47k in the B+ feed? What voltage is at the node where it joins the two 200k plate resistors?

 

[cameron spinks]

Have you measured the 47k in the B+ feed? What voltage is at the node where it joins the two 200k plate resistors?

I get 284v

 

[cameron spinks]

What voltage du you read from pin 3 & 8 on the 12AX7 ...?.... and for that matter 2 & 7 (the later should only be a few millivolts).

Per

OK I get the following..

3 = 3.7v
8= 3.7v
2= 1mV
7= 1mV

 

[AnalogPackrat]

I get 284v

Well, that means you're only dropping 7V across each 200k plate resistor. I = 7V / 200k = 35uA. You should be dropping 110V / 200k = 550uA. Your first 12AX7 is not drawing any current which is why all of the B+ nodes are high.

Something either is wired incorrectly or one or more components are the wrong value or damaged. Are you certain that 47k in the B+ feed to the 12AX7 isn't 470k?

 

[cameron spinks]

Well, that means you're only dropping 7V across each 200k plate resistor. I = 7V / 200k = 35uA. You should be dropping 110V / 200k = 550uA. Your first 12AX7 is not drawing any current which is why all of the B+ nodes are high.

Something either is wired incorrectly or one or more components are the wrong value or damaged. Are you certain that 47k in the B+ feed to the 12AX7 isn't 470k?

Positive to the 47k in B+ being correct value

All the transformer wires are all colour coded on the board. So it's pretty hard to mess up. That's really the only wiring on it.