🎵One of these things is not like the other! 🎶

[Pauleo1214]

Don't you love when your combo build works the first time, 75% of the time?

I am currently on a hot mess streak. My last four pcbs (of which I built successfully before) produce dry signal but no modulation.
I decided to focus on another weird build, four HAARPs in parallel. A QUAARP if you will. Except one of them doesn't produce any modulation. The PCB in question is the one on the upper left (component side up), upper right (pot side up).

So far i checked all my resistors, reflowed all my solder joints, checked that the ICs are getting proper voltage (they are), swapped the regulator and tl072's, and swapped one of the EEPROMs. No dice. Could anyone who is an eagle eye with resistor color bands see if I possibly subbed a wrong value? My next guess besides that is a broken trace.

 

[Pauleo1214]

My DMM has a Beep function on the 200 ohm setting of resistance reading. Touch any two of the four points with the probes produces a beep.

I read article that described contiuity tests using the diode mode; any reading of 0.000V indicates true continuity between two points. Any small reading indicates current flows through but with resistance. A reading of 0L indicates no current flows through (no contiuity). Touching any of the four points you highlighted produces the 0.000V reading.

This puts me back at square 1 with the board though.

 

[music6000]

If you have the Beep function on your DMM & the 4 red circles all Beep, you don't need the jumper!

Test Your FV1 Legs for Continuity:

 

[Pauleo1214]

Test Your FV1 Legs for Continuity:

View attachment 25380

All the points have continuity between the pins and next components but i haven't tested at the diodes yet.

 

[Pauleo1214]

Confirmed continuity from the FV-1 to the diodes. At this point, it just has to be the FV-1 being faulty. I re-flowed the legs on it twice with no change . I have a replacement board coming Monday. Thanks for your help!