DIY Front End 2022

[Ben Mah]

With anodized/painted chassis pieces, make sure that all of the pieces behave as one electrically.

 

[Monk55]

I’m a fan

 

[jdg123]

I am stumped... built the boards, attached them to a known good PSU and got no signal through. I must have misunderstood something, somewhere.

All connections are fine, continuity tested. What I put on the newer boards was the C6, the pot (P1) instead of the R6. I used R13 though it seemed unnecessary and left off R14 - I connected nothing to GF port.

It is single ended input so -IN is connected to VG, VG is connected to ground. V+ gets +15VDC, V- gets -14.9VDC. Out goes to Out except I have not signal out.

Anyone have an idea of what I must have done wrong???

 

[Ben Mah]

Did you adjust the pot to zero the output offset?

Are your signal input and output grounds connected to VG?

 

[jdg123]

Good questions. There IS no output so there is no offset. Indeed it measures as 0

My guess is that there is a grounding issue but there is only ONE ground in the whole Schematic: VG. -IN goes to that VG and VG goes to the PSU ground which goes to an actual plate of aluminum. I have continuity from VG to the aluminum plate.

 

[Ben Mah]

Please post a picture showing everything.

Also please tidy up the wires by grouping them together so it is easier to see what is going on. I.E. twist V+ V- G together, IN+ and IN G together, and OUT+ and OUT G together.

 

[jdg123]

Thank you for following me on my thought journey. As I contemplated how to do what you've asked it occurred to me that I may have made assumptions about how to feed this circuit. I KNOW it is connected correctly to PSU but I am unsure about how to volume control the input.

Is it just like normal: center of RCA to center terminal of log pot, one terminal on either side goes to ground and the other goes to +IN?

 

[william2001]

I would want to see the voltage across R7 and R8 so that I could calculate these currents. Need to see if these stages are alive or not.

Wiper goes to +IN (C1 on your board)

Check DC offset at R5, not at the "OUT" connection (DC is blocked by the capacitor, as intended)

 

[Ben Mah]

What William said.

But double check all connections. A picture of the overall layout would allow others to check.

Once all connections are confirmed to be correct and still no joy, then onto voltage checks.

 

[jdg123]

thanks guys. will do.

 

[jdg123]

Voltage across R7 is 1.5vdc, across R8 0.002vdc at 5 to ground: -14.6vdc. Something tells me this is not good...

From the big picture and indeed any picture I could send you can't tell much. The space where the FE 2022 is, once was occupied by Waynes 2018 FE, I am attempting to compare one to the other.

 

[jdg123]

Oh, and I misstated before: center of RCA goes to one end of pot, center terminal of pot goes to +IN and the last terminal of pot goes to ground. Yes, it is hooked up correctly ;-)

 

[Ben Mah]

Voltmeter probes at R5 and VG, what voltage?

 

[jdg123]

that voltage R5 to VG was 14.6vdc

 

[Ben Mah]

Adjust the pot to zero that voltage.

 

[gsrchrisu]

Following, I am using a SMPS. When I test between VG and r5 i get 250mv on one channel and 180mv on the other. I didnt use a pot but the resistor that came with the kit installed in r6. Are those values too high, it sounds fine when listening.

 

[Ben Mah]

Close enough, just enjoy the music.

 

[william2001]

jdg - both channels same readings?

 

[jdg123]

OK, got R5 to VG to zero - new readings for R7: 1.5vdc and R8: 1.0vdc

 

[jdg123]

Both channels the same