Aion Vector Delay - Output Signal Issue

[shorin13]

All,

My son recently built the Aion Vector (Deep Blue Delay clone) kit.  Delay effects work, but have one issue: Processed signal / output is significantly lower than unity, or output with box in bypass mode / powered off.  Best guess is wet output is 50-70% less than the input signal, or volume of bass plugged directly into an amp.  Have tested box with 4 different basses (2 passive, 2 active) and 2 different amps, same "volume drop" when Vector is powered happens with each test. Hoping someone can help with troubleshooting, point us in the right direction to fix this problem.

Build Doc: https://aionfx.com/app/files/docs/vector_kit_documentation.pdf

Pics of the box and PCBs attached.

We've also measured voltages for both the PT2399 and TL072 ICs, with all 3 pots both "turned down" (Fully CCW) and "turned up" (Fully CW).  Power source is 9V DC + outer / - inner adapter, with a measured output of 9.04V

PT2399:
Full CCW:                                              Full CW:
Pin          V                                            Pin          V
1            5.00                                        1            5.00
2            2.50                                        2            2.50
3            0.00                                        3            0.00
4            0.00                                        4            0.00
5            0.71                                        5            2.47
6            2.45                                        6            2.51
7            0.29                                        7            0.14
8            0.70                                        8            1.33
9            2.51                                        9            2.51
10          2.51                                        10          2.51
11          2.51                                        11          2.51
12          2.51                                        12          2.51
13          2.51                                        13          2.51
14          2.51                                        14          2.51
15          2.51                                        15          2.51
16          2.51                                        16          2.51

TL072:
Full CCW:                                              Full CW:
Pin          V                                            Pin          V
1           3.95                                         1           4.01
2           3.96                                         2           4.01
3           3.94                                         3           3.99
4           0.00                                         4           0.00
5           3.94                                         5           3.99
6           3.96                                         6           2.24
7           3.95                                         7           1.30
8           7.92                                         8           8.03

Thanks in advance for any / all ideas on what could be going on with this.  Also much thanks to Kevin VandeKrol of Aion for answering questions we had, and pointing us to the board.  Feel free to post any idea you may have / request further info or pictures, etc.  Will respond ASAP.

[antonis]

Hi & Welcome..

TL072 measurements should be identical for any POTs setting due to various DC blocking caps..
About 60mV variation for IC1A could be considered acceptable but IC1B has a major issue..

I'd check for C19 short or pin 7, R4, C19, R17, MIX pot wiper circuitry..

[shorin13]

Antonis, thanks much for the reply.  We'll check the PCB later per your instructions, I'll post what we find.

[shorin13]

@Antonis: You were dead on with your suggestions.   Pin 7 on the TL072 socket hadn't been soldered to the PCB, Pin 6 had so little it may as well not have been.  Took care of both of those, swapped out the mix pot for good measure, and wet signal / volume is now at unity.  Next to no difference between bypass output and wet when mix is turned all the way down, think we can call this a success.

Thanks again for your help, son and I very much appreciate it. 

[antonis]

Both you and your son are welcome..

P.S.
You could raise output volume a bit by raising R4 (12k) value (up to 15k -18k) with the risk of distorted out put..