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Folks,
magically the problem disappeared.
I plugged in the guitar one last time, a couple of days later, just to hear the always nice Aquaboy repeats....

I wonder if this could be related to some type of residual charge in C30, thus changing all biasing in the compander.
Next time this happens I will try to short it (C30).

best

Dear all,
thanks for the superfast reply, and kind words (Madbean, Scruffie and Gordo).
Indeed, to be respectful with everyone's time I take pride in providing precise info, hoping that it can benefit others and also it is a small price to pay to drink from this well of knowledge.

Thanks Madbean - much obliged for the detailed step by step.

Here are my results:

1) checked signal path between pins 10/11 through the 1uF cap (C30). I removed the compander and measured the capacitance between the pin 10/11 at the socket, and pin 3 of the Mix knob. Got 1uF, so there's continuity. No leaks to GND.
2) measured all voltages, comparing them with the new version.
All on the dot, except on pins 10,11,12, of the compander which I reproduce below (Vc=9.23V, so it is pretty close to the Vc=9.4V):
pin 10 = 1.33V (should've been 3.10V)
pin 11 = 1.33V (should've been 3.10V)
pin 12 = 5.42V (should've been 1.84V)

3) removed R37, and the same voltages as reported earlier remained.

4) I also checked whether there was continuity between the feedback and mix pots, so since they are in parallel, when measuring form pin 3 (either one of course) to ground I had 25k, which is what one would expect.

So I guess the compander is no longer working. I will keep trying every single one I have.

About V571 - thanks for the plug, Scruffie. I checked their data sheet and it is a copy and paste version... min voltage of 6V, and max 18 V, so looks like I am game and it is a drop in replacement. If all else fails, I'll do that.

Anyone has experience in describing its performance? Coolaudio has a license, or just bought the mask set for making the chips? In other words, anyone knows if they redesigned the chip to comply with more modern process, yet retaining the same sonic characteristics?

Again thanks everyone for the support. My wishes of a enjoyable Sunday to all,
best,
gilberto

Howdy folks,
seems to be a common problem, I did go through some of the posts to get some help before bugging everyone, but this is what I am facing - no delay signal out of a ABDX 2013. First off, it was working, indeed, it has been forking for the last 2 years.

Here's the info:
(1) Project Name: ABDX 2013, I am unsing 2 MN3205 and the associated clock MN3102; I did set the voltage properly, and it is around 8.84V. At the compander I set R13 and R14 with 10k each. Forst time I built I used to test all my MN3008, so I socketed R13 & R14.

(2) General description of the problem:
No wet signal, only dry signal through
(3) Steps that you have taken to try to resolve the issue:
a) first I followed the troubleshooting in the manual:
Feedback 1/2, Mix 1/2, Delay max.
- checked the signal at pin7 of the compander (check -ok)
- pin 7 at IC3 (BBD) to confirm BBD was receiving the signal (check - ok)
Since I had had it working before, I had set it properly the jumpers.

This is what else I did:
- checked the signal at the output of LF353 - (pin1) - Check, ok
- checked the signal at the pin 5 of the compander - check, ok
- followed the delayed signal through the 2 BBDs - check, ok. I adjusted again the bias to make sure no distortion was going through, as well as the cancelling pot to reduce clock noise.
- checked the signals at pins 14/15 of the compander - check, ok.
- checked the signals at pins 10/11 of the compander - NO SIGNAL.

So at that point I concluded that the problem would be with the compander I am using, a SA571 Phillips made in Thailand.


(4) List any substitutions you used for parts/values

I had a stash of companders, and started replacing one at a time. Once I reached my 6th compander, I started wondering whether there wouldn't be something else.

I then checked T1 which sets the levels for mixing and feedback, and let it half way. I did check it in full CW and full CCW.

I concluded that the BBDs are working and the delay in the signal has been produced. Along the signal path, the signal disappears at the output of the compander (pins 10/11), and therefore the compander must be shot.

I changed companders, and maybe I got a bad batch, because none worked.

My questions to the forum:

Did I miss anything?
Is it common to have bad companders?
I checked mouser and digikey - DIP companders are obsolete. Where can I get some? Small Bear does not have them.

Thanks all for your time reading.
best
gilberto

Yep. Perhaps messing with C39 may help.
Thanks!

Thanks Scruffie for the fast reply,
but I am afraid I was not referring to the intrinsic darkness of the repeats, but rather the direct signal.
I see  C3 & R5, C6 & R9, their 3dB roll off frequency is about 14kHz; so I think they are not the culprit.
I don't think C5/R10, C4/R7 matter either (>200kHz). Not sure how to improve it.
thanks for the tip!
best
gmr

Hi guys-
I finished my ABDX, and although I really like the delay, I feel that the sound is a bit dark (not only the repeats, but the direct signal).

I have not modded any of the capacitors in the signal path; anyone has any idea how I can make it a bit brighter?
thanks!
gmr

Thanks guys.
I still get a bit of whine, which I think may go away once it is boxed/decrease the max delay time.
Distortion is mostly gone. But there's always a bit, which I guess it is just me being a purist and comparing the sound with a digital delay. Chances are we cannot get rid of distortion completely.

The configuration which I found to work well was:
V=12V
R13/14=22k
R27/55=10k (I guess 1k is equaly as good).

I also found that there seems to be some interaction between all pots; meaning, if I bias BBD2 with too much gain, I get T1 messed up and need to recalibrate it. Cancel has a minor dependence on the BIAS pots.

Next step is to get the modulation working properly. I do not like the way it sounds, and it could be my vactrol only works at 9V.

I ended up testing all my MN3008, and indeed,some Asian eBayers will sell you fakes (or I just could not bias them with the numerous combinations of compander resistors, supply voltage and R13/14 I had tried). In 8 I bought, Ihad 4 working and 4 not working.

I hope these comments will help people in the future! The documentation lacks some info that is perhaps dispersed between multiple threads. Maybe this thread can help a bit in that direction.

Thanks everyone for your help!
gmr

Thanks Scruffie.
This is what I was thinking would happen.
I was able to significantly reduce the whine in the repeats by carefully adjusting the cancel pot. But there is still a constant whine, so will see if that goes away once I box it. If not, I will just have to dial up my clock and reduce the delay time, as you pointed out.

Now, there is a bit of distortion in the repeats, but I was not able to get rid of it only by adjusting the bias and the input resistors (R55 - which was supposed to be 1k for a MN3008, but I put 10k). I noticed that the signal into pin 7 of the first BBD was a bit distorted, so should I keep on nudging R13 and R14 until I get a clean signal there? Or is there another way to lower the compander gain? If the latter, how can I do it?

Thanks Scruffie for the help. This is a fun project!
gmr

Thanks Morgan,
I checked the issues with the Vactrol. The good thing about having an LED to monitor it is that we can easily check modulation.

Clock noise -  may go away once I box it (I hope so Scruffie! you may very well be right - with my audio probe I could hear the clock without even touching the pins, because of the capacitive coupling that should decrease once I clear up all the wiring). But the main issue  is that I am pushing the delay to a 5-6kHz (long delay times), and that seems to leak into the repeats. Once I increase the frequency (or decrease the delay time), then indeed it goes away. Oh well, I guess I would need to double the number of BBDs ...

thanks a bunch guys! The SA issue is very subtle, glad to hear that it can be solved by nudging the bias on pin 7,
gmr

Great!! thanks so much.
Did work (partly).
I socketed R13/R14, and ended up 47K/33K, and the voltage on pin 7/SA571 now reads roughly 6.57, or close to half the supply voltage of 12V. Now I have a window on the bias pot to get the signal through. I get repeats, and can have them varying as intended.

The only remaining critical issue is that the clock signal goes with the repeats, and I do not know how to get rid of it. It is quite a bit fainter, but I can definitely hear it.

Any tips on how to clean it up?...

I am using MN3008s,

thanks so much once again!
gmr

Howdy folks,
seems like several people had this problem before, but I am running of ideas as to how to further debug my Aquaboy deluxe.

I am powering the ABDX with a LM317 where I could adjust the voltage precisely to what I wanted.

Here are the IC voltages:
IC1 LF353N
Pin 1 -> 6V
Pin 2 -> 6V
Pin 3 -> 5.97V
Pin 4 -> 0V
Pin 5 -> 5.97V
Pin 6 -> 6V
Pin 7 -> 6V
Pin 8 -> 12V

IC2 SA571N
Pin 1 -> 0.9V   Pin 9 -> 1.8V
Pin 2 -> 1.8V   Pin 10 -> 4.8V
Pin 3 -> 1.8V   Pin 11 -> 4.8V
Pin 4 -> 0V      Pin 12 -> 1.8V
Pin 5 -> 1.8V   Pin 13 -> 12.0V
Pin 6 -> 1.8V   Pin 14 -> 1.8V
Pin 7 -> 3.0V   Pin 15 -> 1.8V
Pin 8 -> 1.8V   Pin 16 -> 0.7V

IC3 MN3008
Pin 1 -> 11.8V
Pin 2 -> 5.8V (clock from MN3101)
Pin 3 -> 10.8V
Pin 4 -> 10.8V
Pin 5 -> 0V
Pin 6 -> 5.8V (Clock from MN3101)
Pin 7 -> 3.5V
Pin 8 -> 10.8V

IC5 MN3101
Pin 1 -> 11.8V
Pin 2 -> 5.9V
Pin 3 -> 0V
Pin 4 -> 5.9V
Pin 5 -> 5.2V
Pin 6 -> 6.4V
Pin 7 -> 6V
Pin 8 -> 0.8V

IC6 TL062
1 - square wave
2 - triangle wave
3 - square wave + offset
4 - 0
5,6,7 - triangle wave
8 - 12V

LFO working fine with the Vactrol I built with an LED and LDR.

I audio probed the signal all the way from the input through the 571 (pin 2, a bit distorted there), into pin 7 of the first BBD (MN 3008). And then pins 3/4 of the BBD, no signal but whine. I put an oscilloscope probe there and I got the clock signal, amplitude around a couple of volts.

I tested several BBDs, suspecting they could be the problem, but all 14 I had gave me the same outcome, and although many were from China (Janeh2100 and Funkward eBay stores), a few were from a real store I found (the last 2 NOS they had), and some pulls from a defunct DMM.

I omitted D2 and D3, as suggested.

See the pics below.

Any help would be greatly appreciated!
thanks!
gmr

Thanks Jacob-
audio probe rules!
I feel stupid for not knowing it, so this was a great deal for me.
I was able to troubleshoot the problem.
Cavedweller working, a bit too dark for my taste, but I will do the C3 mod to see if I can brighten it up.
Also kind of noisy, but excellent experience!

thanks!

I answered myself with this link:

http://www.diystompboxes.com/pedals/debug.html

does this work?... 

never tried, so I ought to take a look at it.

Thanks Jacob-
sorry about the dumb question - I have been using my guitar as an audio probe, and followed the signal. But it is presumably not the ideal one; what should I use?
thanks!

hi there,
thanks for the fast reply!
cave dweller has no tl072
using the pcb from madbean, so wiring was minimum (and triple checked)...