DigDug2 - No Wah *Solved*

[DLW]

The good:
1. Tremolo sequencer, LED sequence indicators, and all potentiometers work fine.
2. Tap tempo works well.
3. Sequence output operates tapanator wah/phase/tremolo pedals fine.
4. IC1-4 and REG voltages are all within specs on BOM.
5. LED side of Vactrol 1 causes an LED to flash when placed on the vactrol pins. Thus, I assume vactrol 1 is getting the appropriate signal.

The bad:
1. The wah signal is a continuous, muffled drone. The "wah" volume pot and "gain 1" trimmer adjust the volume as expected, however.
2. Q2 S voltage is lower than the value listed in the BOM (1.34 vs 2.7). I swapped ~5 different 2N5457 from a variety of manufacturers and vendors, but 1.34 was as high as I could get it.
3. Q1 C is higher than the value listed in the BOM (5.7 vs 4.7).
4. Unlike Vactrol 1, the LED side of Vactrol 2 does not cause an LED to emit light when placed on the pins.
5. The "PATT" LED near the tap tempo switch does not work. A separate LED placed on the pads also does not function. Not sure if this is an related or separate problem to that listed above. I could live with this, if everything else worked.

Anyone have any specific suggestions on how I can get the wah to work?

Voltages:
Wall wart = 9.7V

       IC1   IC2   IC3   IC4   REG    Q1    Q2
1=   4.6   4.6   5.1    0      9.42   5.7*  9.41
2=   4.6   4.6   Var    0      0        0.6   1.34*
3=   4.6   4.6   Var    4.4   5.14   0       0
4=   0      0      5.15  0
5=   4.6   4.6   Var    0
6=   4.6   4.6   Var    0
7=   4.6   4.6   Var    0
8=   9.4   9.4   0       0
9=                           0
10=                         0
11=                         0
12=                         5.15
13=                         0
14=                         0
15=                         5.67
16=                         5.15

Picture of board:

[DLW]

Also, FWIW... There is a discrepancy in the bill of materials and voltage section of the build guide. Q1 is noted as 2N5088 in the BOM and 2N5087 in the voltage table. Based on the pinout and voltages, I assume 2N5088 is the correct transistor.

[DLW]

Anyone have any ideas?

[DLW]

*Solved*
Backwards vactrol :|

[gordo]

Dude, I saw this and followed. Good to hear you got it sorted out cuz you had a nice troubleshoot thread going and I'm feeling bad I didn't jump in.

[DLW]

Dude, I saw this and followed. Good to hear you got it sorted out cuz you had a nice troubleshoot thread going and I'm feeling bad I didn't jump in.

Thanks, man. I'm just happy to get this thing out of my fail pail.

The good news is that it is remarkably difficult to cook a vactrol. I applied a fair amount of heat to get it off, bent the legs around, and resoldered. Voila!... will be socketing vactrols in the future, anyways. Haha

[madbean]

Where did you get that vactrol? I've never seen an NSL variety 5C3.

Also, glad you got it worked out - sorry I did not get to the thread sooner.

[DLW]

Where did you get that vactrol? I've never seen an NSL variety 5C3.

Also, glad you got it worked out - sorry I did not get to the thread sooner.

Hmmm. I don't remember. It could be a fake, afaik. I should probably keep better records of where I get parts.

No worries. I buy boards from here and other places fully accepting the fact that tech support is a bonus, not a right.

[gordo]

Having cooked a few in the past I've resigned myself to socketing by default.  They're spendy little devils for one thing...