Aquaboy 2016 - Very low and distorted delay

[WAXOU]

Hello all,

After almost a year away from the workbench, I'm back with an aquaboy.

Everything went well so far, voltages were consistent with the build doc and I've got sound and delays.
Freq . is 6.6Hz and the pedals is running at 9V.
But since I started to calibrate with audio probing, delays are now weak and distorted, Pin3 and 4 of the Mn3005 are at 8.40V and Pin7 is 5.3V.

If I audio probe on pin7, I've got a clean sound.

Is it possible that I've fried the mn3005 Chip while calibrating ?

Thank

[Ariosto]

I have the same problem with mine, only that still stranger. I could calibrate the whole thing, worked OK out the box, and as soon as I boxed everything (PRR and modulation PCB included) BUMP! no delay at all. I tried to reclibrate the trimpots and all I´ve got now is a distorted and low delay signal. The Universe is a very strange place.

Ariosto

[skeeter]

My one had  repeats  only when I shook it -non boxed ,nothing worked otherwise,I think pcbs with solder mask hide bad traces or damage the traces ,I removed a resistor that would show 0 then when the bypas switch was pressed its  real value ,I realized it was part of the buffered bypass ,damaged the trace removing it.

[WAXOU]

Well, hello again, and back on this one today with no luck again.

Here is where I am :

I've got audio signal on pin3 of IC3, but very distorted.
The sweet spot to get this weak distorted signal is about half the Bias pot (though it says 1/4 to 1/6 in the doc).
When I try the pedal, i've got no delays but a kind of self oscilation that becomes a sort of slapback in the first 1/8 of the delay pot., then nothing passed that point.

Here are the voltages I've got at 6,5 kHz and 8,58V power supply (* are the voltage that I found different from the build doc).

IC1 : 4558D
--------------
PIN 1 : 4,29
PIN 2 : 4,29
PIN 3 : 4,29
PIN 4 : 0
PIN 5 : 4,29
PIN 6 : 4,29
PIN 7 : 4,29
PIN 8 : 8,58

IC2 : V571D
--------------
PIN 1 : 1,3
PIN 2 : 1,85
PIN 3 : 1,85
PIN 4 : 0
PIN 5 : 1,85
PIN 6 : 1,85
PIN 7 : 2,9
PIN 8 : 1,85
PIN 9 : 1,85
PIN 10 : 3,05
PIN 11 : 3,05
PIN 12 : 1,85
PIN 13 : 8,58
PIN 14 : 1,85
PIN 15 : 1,85
PIN 16 : 1,07

IC3 : Xvive MN3005
----------------------
PIN 1 : 8,55
PIN 2 : 3,99
*PIN 3 : 8
*PIN 4 : 7,96
PIN 5 : 0
PIN 6 : 3,99
PIN 7 : 4,3
PIN 8 : 0,54

IC4 : MN3101
----------------
PIN 1 : 7,95
PIN 2 : 3,99
PIN 3 : 0
PIN 4 : 3,99
PIN 5 : 3,97
PIN 6 : 3,9
PIN 7 : 3,9
PIN 8 : 0,53

The only change I've made from the BOM is a V571D in place of a NE570.

I'm attaching some pics of the board too, maybe you'll see something I've missed.

If you guys have some time to help me with this one, that'll be awesome.

Thx

[madbean]

No doubt pins 3 and 4 of the MN3005 are the problem here. You have twice the expected voltage. My first thought was you did not use 100k for R20 and R21 but it appears you have.

Here are the possibilities (in no order):
micro bridge with solder
bad chip
bad socket (it can happen)
bad board or traces
wrong trimmer (should say 103 on it for 10k)

First thing I would do is pop out the MN3005. Remelt all the solder joints around there. Connect power (with chip still out) and measure the voltages on pins 3 and 4 of the empty socket. If you have a continuity checker, make sure that pins 3 and 4 do not have continuity with any of parts of the socket (without power applied).

[WAXOU]

Hello Brian and thx fo the answer.

I've checked the trimmers, I've got a 20k for Bias, a 10k for Cancel, and a 1M for Clock.
I've removed the MN3005 and mesure the voltages, remelt the joints and mesure again and it is still twice what it should be.
I've totaly remove the socket and mesure directly on the board, same voltages.
I've removed R20 and R21 and put on new ones, still twice the voltages...
I also change the Cancel Trimmer, no luck too. (I've got 8,47v on the three legs of the trimmer, don't know if it's normal though).

Maybe be I fryed the PCB somehow...