Steps 34 and 35

[wertt]

I finished my first C84 this weekend and the build went without a hitch. I wrapped up the second this afternoon and am having some trouble. At step 34 and 35, I'm measuring -48V and -34V. I don't see any problem solder spots and have double checked all of my diodes, polarized caps, etc. Any ideas on where I should start troubleshooting?

[tpryan]

You're sure you're measuring with respect to J3, pin 2?
Are any wires crossed in the harness? Are you getting the proper supply voltages at J3?

[wertt]

myseriously, it's testing ok this morning. i'm going to keep playing with it to see if i can get it to go wacky again.

also, which pins on u1 are 4 and 8? i'm assuming i'm testing the right ones as they started out at +/- 14 and when i changed the potentiometers they moved to +/- 18, but i hope i'm testing the right pins. should they be at opposite corners of the chip?

lastly, my gain knob for the second channel didn't come with the stop pin or adhesive foil. it also wasn't in the clear tube like the first one...just a little baggy. i'm assuming this just means i'll be able to turn from the highest gain setting to the lowest and won't impair it's functionality at all. is this correct?

[dkatz42]

i hope i'm testing the right pins. should they be at opposite corners of the chip?

Yep. Pin 1 may be marked with a dot or somesuch; alternatively, if one end of the chip is marked, pin 1 is on the upper left if the marked end of the chip is up. Then the pins are numbered counterclockwise around the chip.
http://en.wikipedia.org/wiki/Dual_in-line_package#Orientation_and_pin_numbering

lastly, my gain knob for the second channel didn't come with the stop pin or adhesive foil. it also wasn't in the clear tube like the first one...just a little baggy. i'm assuming this just means i'll be able to turn from the highest gain setting to the lowest and won't impair it's functionality at all. is this correct?

Yep, although going from the lowest to the highest gain by accident could be pretty uncomfortable. I was missing the pin on one kit, and just cut off a wee bit of resistor lead and stuck it in the hole with a bit of tape.