Seventh Circle Audio

Step 36 page 17 of the assembly instructions mentions U2 - does this actually mean U3? (Maybe U2 was a trademark infringement. . . .) I don't have a U2 silkscreened on my board or in my BOM.

Voltages at U1 and U3, pin 8 are 11.6 on both of them and they cycle through some values for a few seconds before settling on 11.6. Also, I do have sockets in these spots if that matters.

U1 and U3 pin 4 are both -14.

I checked diodes and caps mentioned in step 37 and all are correct. I did have trouble with Q5 - had the wrong value and replaced it with the correct value and it's not as clean as Q6, 12, and 13 - still looks like it's making a good connection.

Thanks for the help.

Been working on this - no luck yet.

Rechecked soldering etc.

For U1 and U 3 I was getting about -14 at pin 4 but pin 8 was still reading 11.6 I decided to try adjusting R68 and R72 until I got 14 at pn 8 but then pin 4 was -18.

Any ideas as to what to check next?

Step 36 page 17 of the assembly instructions mentions U2 - does this actually mean U3?

Yes, corrected instructions are up now.

For U1 and U 3 I was getting about -14 at pin 4 but pin 8 was still reading 11.6 I decided to try adjusting R68 and R72 until I got 14 at pn 8 but then pin 4 was -18.

Are you saying you can't adjust R68 to get +18v? Are you sure that R68 and R72 are both 1K pots (marked 102)? Have you got the right values in R69 and R70? Is U4 noticeably warmer than U5?

R68, R72, R69, R70 values are correct.
U4 seems to be a little warmer than U5, but not much, and really not what I would call hot at all.

I have adjusted R68 and R72 and I'm getting volatges of
pin 4, -23.56
pin 8, 18.94
on both U1 and U2.

Should I move on? I was assuming the pin4/pin8 values should be +18, -18.

Thanks for the help.

billkahler \$m[1]:Should I move on? I was assuming the pin4/pin8 values should be +18, -18.

The values should be +- 18; adjust the negative supply (whichever pot it is) to bring that back down to -18 and you'll be golden.

Thanks for that dkatz.

Voltages are reading 18.06 at pin 4 and -18.08 at pin 8. Do they need to be exact?

I think my problem may have been adjusting R72 too far counter clockwise. Doooh!

That's about as close as you're going to get it (and probably within the accuracy of your DMM.)