Pultec eqp1a (drip) - gain loss after 12AU7..

[hugo]

Hi,
After solving my power issue, i have a last problem.. I still have a -12db between input and output. All testing points are ok except one, just after the 12AU7. I should have 40v, and i have 25v. May i change the 12AU7 with an other type of tube or this problem can be solved by an other way ?..
Thank you.

 

[ruffrecords]

It probably means you have an incorrect component values somewhere.

Cheers

ian

 

[hugo]

Hi,  thank you for your answer, but i would like to know in which section i have to check .... the strange thing is between the 2 +40v testing point, there is only the valve tube..

 

[My3gger]

Do you work from the same schematic like this one?
http://www.recproaudio.com/diy_pro_audio/diy_files/eqp_1a/eqp-1a_schem.jpg
If so,  i would check all resistors to the right side from two 200K/1W where high voltage comes in. Shouldn't be too hard and it is probably not tube problem.

 

[hugo]

Drip do not show the layout of their pcbs, so it is difficult to say it is the same schematic..
I have the same problem on 2 units, like a wiring problem but signal go in, go out...i just lose 12db...i will check the amp resistors, but i would prefer to have a process to follow the signal and to find where the loss starts..

 

[My3gger]

Compare Drip's schematic with one i posted, voltages are there and should be pretty close to follow if it is really EQP-1A. Takes a little time without overlay...

 

[dbonin]

For future builders:  The v3 DRIP PCB's have that test point mislabeled - it is actually connected to pin 2, which is the grid. My 12au7 grids test at about 26v  (pins 2 and 7).
The 40v test points are related to the cathodes on pin 3 and 8.