Aquaboy DX

[uber]

So I have got my Aquaboy DX assembled and have been unsuccessful in trying to bias the delay and get it up and running.

Perhaps I misunderstood something in the build doc, so here's what I did:

Using MN3205, MN3201 - power is regulated 9v

Jumpered R55, R58, R27
Socketed R56 with 470k
Included D1, D2, and D3

Before starting to bias, I was only able to get the frequency on pin 2 or 4 of MN3102 to 7.37 when I adjusted the CLOCK trim to the lowest position.  The values below are measured with the CLOCK trim in that poisition and the pots set up as described in the bias section.

I also will attach a picture in case there is something glaring that I am missing.

Thanks so much in advance for helping out!

Q1
C:   9.02
B:   4.126
E:   3.697

Q2
C:   9.02
B:   started ~3.5 V and decreased to 0V
E:   started ~3.0 V and decreased to 0V

Q3
C:   9.02
B:   3.935
E:   3.356
Q4
C:   9.02
B:   3.35
E:   2.77


IC1
   Pin 1:      4.51      Pin 5:      9.02
   Pin 2:      4.51      Pin 6:      4.507
   Pin 3:      4.50      Pin 7:      4.509
   Pin 4:      0      Pin 8:      4.505

IC2
   Pin 1:      .003         Pin 9:      0
   Pin 2:      -.302      Pin 10:      0
   Pin 3:      -.27         Pin 11:      0
   Pin 4:      0         Pin 12:      0
   Pin 5:      .58         Pin 13:      9.02
   Pin 6:      2V drops to 0   Pin 14:      .30
   Pin 7:      .53         Pin 15:      .25
   Pin 8:      0         Pin 16:      0   

IC3
   Pin 1:      0              Pin 5:      8.05
   Pin 2:      4.015      Pin 6:      4.012
   Pin 3:      4.096      Pin 7:      3.36
   Pin 4:      4.092      Pin 8:      7.58

IC4
   Pin 1:      0              Pin 5:      8.05
   Pin 2:      4.016      Pin 6:      4.013
   Pin 3:      3.962      Pin 7:      3.507
   Pin 4:      3.963      Pin 8:      7.58
   
IC5
        Pin 1:      8.06              Pin 5:      4.264
   Pin 2:      4.017      Pin 6:      3.789
   Pin 3:      0              Pin 7:      3.816
   Pin 4:      4.016      Pin 8:      7.51
   

IC6
        Pin 1:      0 - 8              Pin 5:      3.8 – 5.2
   Pin 2:      3.9 - 5      Pin 6:      3.8 – 5.2
   Pin 3:      3.7 – 5.2           Pin 7:      3.8 – 5.2
   Pin 4:      0              Pin 8:      9.02
   

[Scruffie]

Your compander voltages look all kinds of wrong...

[uber]

Totally, I recognize that and looked at the schematic...  What would cause that?!?!

[Scruffie]

Bad solder joint or its busted I think are your 2 options.

[uber]

Ok, I'll check the joints... Would this be the culprit behind the fact that the frequency is too high on pin 2 and 4 of MN3102, or is that another mystery to troubleshoot as well?!?

[Scruffie]

I don't think so, what frequency do you get?

[uber]

Before starting to bias, I was only able to get the frequency on pin 2 or 4 of MN3102 to 7.37 when I adjusted the CLOCK trim to the lowest position.  The values below are measured with the CLOCK trim in that poisition and the pots set up as described in the bias section.

I think the upper limit I got when I maxed out the CLOCK trim was between 11-12kz

[Scruffie]

Where was your delay time pot set when taking that? Just to be sure...

C33s value is probably just a bit off due to ceramic tolerance, add an extra small value cap in parallel.

[uber]

I had things setup according to the bias instructions... I often think I get lost when I get done with actually build and its time to test things out since the bias/calibration instructions seem approximate.  These are the "settings" I was using when I made the measurements I provided per the build doc:

· Delay, Mix controls to their center position.
· FDBK at about 1/3 up.
· Rate and Depth controls all the way down.
· Wave switch to the center (off) position.
· BIAS1, BIAS2 and Cancel trimpots to their center position.

I recently got a usb scope as a holiday gift, but I am still figuring it out.  I saw on the build doc that it says

"If you do have a scope, you can use it instead of an audio probe to make the proper adjustments to BIAS1, BIAS2, Clock and the Cancel trimpots. When using a scope, set the Cancel trimpot so that the two output waveforms from pins 3 and 4 of IC4 converge."

I have done a fair amount of searching but have been unable to find a tutorial or example of troubleshooting a pedal build w/ a scope for the uninitiated... Please let me know if you know any resources that would help me learn how to use it to diagnose these and other issues.

I will try adding a cap as you suggested tomorrow. 

Thanks!

[Scruffie]

Delay pot in the middle, there's why your clock was so high, that procedure is not a proper set up procedure for the clock.

So, you probably don't need another cap, just get the compander sorted first.

[uber]

I checked and rechecked the solder joints and the top contacts of the sockets and everything seems fine, so I guess I got a bad IC.  Unfortunately, the NE570 isn't one that I have extras around in my stash, so I'll have to order a replacement soon.  Is there anything perhaps more "common" (for lack of a better term) that I would be able to sub temporarily w/o damaging the circuit in order to verify that the NE570 IC is indeed the issue?

Thanks again for all your help!

[Scruffie]

Afraid not, the NE570 (or NE/SA/V571) aren't like a quad opamp or anything, can't just stick something else in there.

[uber]

Ok, I'll order another and see if things start falling into place when it arrives.