Valley 400 Pre (Self etch & Gerber)

I shared everything in my website.Check and download...

https://analogobsession.wordpress.com/hardware/transamp/

Thanks.

Pin1 always goes to the chassis. The chassis and analogue 0V get connected at on point only.  Basics are here:

https://www.dropbox.com/s/25va7g7kpn0jkxv/grounding101v2.pdf?dl=0

Cheers

Ian

ruffrecords said:

Pin1 always goes to the chassis. The chassis and analogue 0V get connected at on point only.  Basics are here:

https://www.dropbox.com/s/25va7g7kpn0jkxv/grounding101v2.pdf?dl=0

Cheers

Ian

Click to expand...

Thanks for great infos!

With Jensen circuit,phantom power 0V goes to chassis.And it's the "point" that you say,right?

I totally misunderstood.When +48 is off,this will be connected to chassis.Normally +/-15 and +48 grounds are same.

Circuit updated.

Circuit updated and PCB design added.

may be my eyes, but isnt ur switch 2 and 3 are double pole... pcb looks like single pole !

I saw that too, but if you look at say the phantom switch, he is only using 1 pole so it's ok

shouldnt C1 connected in opposite direction ?
looks like C1 + connected to AGRND !

pucho812 said:

I saw that too, but if you look at say the phantom switch, he is only using 1 pole so it's ok

Click to expand...

Yes but it's easy to find two pole for me.

kambo said:

shouldnt C1 connected in opposite direction ?
looks like C1 + connected to AGRND !

Click to expand...

Wow! Thank you so much! Saw my mistake.How i missed it 

i got it now,
silk screen on switches makes them look like they shorted... and one pole  :

Updated first post.Schema and PCB.

Updated first post.

I made one of these from the gerber files that are posted on the site recently I can't get it to work without problems. 

I can run a sine wave into it at 1K but I do not get any real gain and the circuit has lots of noise... 

I can't seem to figure out what the problem is...  I followed the bom so I do not know where I am going wrong...

pucho812 said:

I made one of these from the gerber files that are posted on the site recently I can't get it to work without problems. 

I can run a sine wave into it at 1K but I do not get any real gain and the circuit has lots of noise... 

I can't seem to figure out what the problem is...  I followed the bom so I do not know where I am going wrong...

Click to expand...

I have no idea.But i'm checking my design,right now.

I guess i found and error.

R20 on wrong place.Use jumper instead of R20.Cut trace between C8 and R20.And add 10k resistor to between C8 and R20 pins.

Sorry for error.

Corrected circuit and board.(I will add new board design and gerber files.)

I cut the trace, added the jumper and 10K resistor. Still no signal... Lots of noise though.... I will mess around with this some more and see what I can make happen,  But let me know if you have a working unit...

pucho812 said:

I cut the trace, added the jumper and 10K resistor. Still no signal... Lots of noise though.... I will mess around with this some more and see what I can make happen,  But let me know if you have a working unit...

Click to expand...

I can't find any error instead of this one.I didn't install this circuit,yet.Wrong circuit not working with spice but corrected version working good.

Can you send sine wave after front end?I draw red X.Maybe front end not working...I can't see any other error.

Front end is working fine... I send sine wave in. I redid the jumper across r20 and added the 10K resistor. Now I get sine wave on the output but the 1K pot does not do anything. I think I am going to restart from scratch and try again....  This is not to hard, I will get it right in the end.

pucho812 said:

Front end is working fine... I send sine wave in. I redid the jumper across r20 and added the 10K resistor. Now I get sine wave on the output but the 1K pot does not do anything. I think I am going to restart from scratch and try again....  This is not to hard, I will get it right in the end.

Click to expand...

I don't want that you have trouble because of me.I'm so sorry.It's good to know that it's almost working.

By the way pot is 1K reverse log.And check traces which ones go to pot.

AH HA...  1k REV log... cool. No worries on the trouble... It's diy nothing that cannot be solved.

Did you try it again?