Hi,
this weekend I put the final components on the aquaboy deluxe (2013 version) PCB I had lying around for years. However, no repeats/feedback/whatever is heard when the effect is engaged, only the dry signal. I went over the pcb with both a DMM and an audio probe and found that the problem is probaby somewhere in the BBD's. I get audio on pin 7 of IC 3, but none on pins 3 and 4 (the output pins). Also, the voltages on the DC in pins of the BBD (that should be 5 and 8 if im not mistaken) are way low, which I think causes the issue. I don't have D2 or D3 on the board and I'm using a 15V power supply (3PRR.)
So, does anybody have an idea what can cause this issue? I won't be able to check again until next weekend, but that gives me some time to digest your advice, I guess. Thanks! ;D
What are your voltages on IC 2 like and do you have another you can throw in there? They're very sensitive, I went though 3 troubleshooting my total recall.
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Oof, thats exactly what I wasn't hoping for haha. Im using an NE570 and I only have one, but I'll try to find a couple extra just in case. I'll get back to you with those voltages!
If signal is reaching IC3 but not coming out of it, it's nothing to do with IC2 (and not to chastise you jimi as I know people seem to have problems with them, but they're really not that sensitive, they're an op amp and a bunch of transistors in a package, nothing we don't usually deal with, just don't want that becoming the next 'thing'.)
Post your voltages, then we'll talk :)
Ah thats good news, I looked around online and those NE570's are rather expensive. Another thing I just noticed is that I hear a high pitched whine, which I assume is clock noise (the pitch seems to be modulated slightly in the same rhtyhm at which the rate LED blinks), when audio probing pins 3 and 4 of the two BBD's, as well as on pin 7 of the second BBD (IC4).
I've got some voltages for you; (measured against gnd)
pin - voltage
IC1:
1 - 7.09
2 - 7.09
3 - 7.09
4 - 0
5 - 7.09
6 - 7.09
7 - 7.09
8 - 14.15
IC2:
1 - 1.15
2 - 1.8
3 - 1.8
4 - 0
5 - 1.8
6 - 1.8
7 - 3.09
8 - 1.8
9 - 1.8
10 - 4.7
11 - 4.7
12 - 1.8
13 - 14.15
14 - 1.8
15 - 1.8
16 - 0.8
IC3
1 - 13.9
2 - 6.94
3 - 3.10
4 - 3.10
5 - 0
6 - 6.93
7 - 2.03
8 - 0.95
IC4
1 - 13.9
2 - 6.94
3 - 3.10
4 - 3.10
5 - 0
6 - 6.93
7 - 2.03
8 - 0.95
IC5
1 - 13.96
2 - 6.94
3 - 0
4 - 6.94
5 - 6.21
6 - 7.41
7 - 6.33
8 - 0.93
IC6 (I used a TL072 here instead of a TL062)
1 - 6.13
2 - 6.9
3 - 6.61
4 - 0
5 - 6.98
6 - 7.07
7 - 7.34
8 - 14.16
Q1
1 - 5.35
2 - 4.27
3 - 14.15
Q2
1 - 2.46
2 - 2.97
3 - 14.15
Q3
1 - 2.86
2 - 3.33
3 - 14.15
Q4
1 - 2.26
2 - 2.74
3 - 14.15
Your BBD bias is way too low, you should have in the 6-8V range on pin 7 of each BBD. I hate to ask but you have tried tweaking the bias trimmers while probing, haven't you?
TL072 isn't a great alternative for IC6, don't think it's related to your issue but you might find it adds LFO tick and its higher current draw might explain why you have a low supply voltage. LM1458 would be suitable if you don't have any TL062.
Yes the high pitch whine is clock whine.
Oh man I feel like such an idiot. You're right, that was it! Can't believe I didn't realize that that was the problem.
I agree on the TL072, but it was the best alternative I had at hand. I'm on gonna replace it with something more suitable as soon as I have to order something from a store that sells them :p
Anyway, thanks a lot for your help! Can't wait to box this up!