Aquaboy DX clean signal but no delay

[murdog47]

Been beating my head over this one. Took my time and made sure all component values were correct, etc, etc. So I get clean signal passing through the circuit but no delay. Per the troubleshooting in the build docs, audio probe at pin 7 of IC2 passes signal, Pin 7 of IC3 passes signal and BBD jumpers are set correctly. Also the build DOC states that there should be power to pin 1 and ground to pin 5 of the MN3005. Looking at a data sheet it looks like it should be ground on pin 1 and power to pin 5 (?).  Here are my voltages

LF353N IC1
1. 7.46     8. 14.94
2. 7.46     7. 7.45
3. 7.45     6. 7.46
4. 1.6mv   5. 7.45

NE570N IC2
1. 1.084    16. 0.780
2. 1.806    15. 1.806
3. 1.806    14. 1.806
4. 3.9mv   13. 1.806
5. 1.8       12. 1.806
6. 1.805    11. 4.72
7. 6.63     10. 4.72
8. 1.8       9. 1.806

MN3005 IC3
1. 9.22   8. 8.56
2. 5.1     7. 3.59
3. 7.21    6. 4.9
4. 7.17    5. 5.7mv

MN3101 IC5
1. 9.23     8. 4.5
2. 4.9       7. 4.67
3. 8.0mv   6. 4.46
4. 5.10      5. 4.48

TL062CN IC6
1. Unstable   8. 14.94
2. Unstable   7. Unstable
3. Unstable   6. Unstable
4. 1.3mv      5. Unstable

Any ideas folks?

[Scruffie]

If you look at the datasheet it says Pin 5 should be negative 15V, so think of this as a bit like making a PNP positive ground fuzz run on negative ground by flipping the components & power connections 

Hmm, why do you only have 9v power hitting your MN3005s compared to your supply of 15V, have you put in the 8v2 zener (D2) for the 3205 model?

Your NE570 too... should have 15v on Pin 13

Something is dragging voltage down.

Shorts, backwards parts, wrong values, follow the power traces.

[murdog47]

I left D2 open as the build docs said to omit...should this be jumpered?

[Droogie]

I had a similar issue (and similar voltages) solved by checking the Clock trim. The trimmer I used had the opposite pin configuration of that shown in the build doc. Once I figured out that it was backwards, everything worked as expected when calibrating. Might be worth a look...

[murdog47]

Mine does in fact have an opposite pinout but being that it is  set at 12 o clock for calibrating I wouldn't think that would make a difference. Did you replace yours all together?

[Scruffie]

I left D2 open as the build docs said to omit...should this be jumpered?

No, you got it right, just checking why the voltage is being pulled down.

IC1 & 6 have voltage as they should from your readings, but 2, 3 & 5 are off from the supply.

Pull out the MN3101 and measure Pin 1, Pull out Both MN3005s and measure Pin 1, Pull out the 570 and measure Pin 13.

[Droogie]

Mine does in fact have an opposite pinout but being that it is  set at 12 o clock for calibrating I wouldn't think that would make a difference. Did you replace yours all together?

Didn't replace, just set trim to reflect that pin 1 on the layout (fully counterclockwise) is pin 3 for my trimmer. Not at home at the minute, but now that you mention it, your contention makes sense. I'll check this evening.

[murdog47]

Attempted a jumper on d2 just for grins and still no signal out of pin 3 on MN3005. Here is where it gets weird. Started checking voltages again and I'm now getting 13.8v at pin 1 on MN3005 and 12.83v at pin 8, the others are bumped a little bit also and the ground on pin 5 bumped down a bit. Also now reading 14.95 at pin 13 of the 570 and 13.58 at pin 1 on the MN3101. The LF353 and TL062 appear unchanged. Attempted to calibrate again and I still have signal at pin 7 of the MN3005 but nothing out of pin 3 or 4.   The only thing I changed was that I jumpered d2. Note: I removed the jumper and it appears to make no difference either way.

[Scruffie]

Attempted a jumper on d2 just for grins and still no signal out of pin 3 on MN3005. Here is where it gets weird. Started checking voltages again and I'm now getting 13.8v at pin 1 on MN3005 and 12.83v at pin 8, the others are bumped a little bit also and the ground on pin 5 bumped down a bit. Also now reading 14.95 at pin 13 of the 570 and 13.58 at pin 1 on the MN3101. The LF353 and TL062 appear unchanged. Attempted to calibrate again and I still have signal at pin 7 of the MN3005 but nothing out of pin 3 or 4.   The only thing I changed was that I jumpered d2. Note: I removed the jumper and it appears to make no difference either way.

Don't jumper it.

Your meter could be on the fritz or you might have a bad joint... what are your new voltages for The MN3005s, 570 & 3101.

Also, where did you source the 3005s from, I tend to not jump to the conclusion that chips are fake but with 3005s it's a lot more prevalent so good to rule them out.

[murdog47]

Turned it on and off several times and I continue to get these higher voltages on my power pins. I think I am reading good voltages now but still no signal out of the MN3005 pins 3 or 4.

[murdog47]

New Voltages

MN3005

1. 13.40
2. 6.72
3. 10.12
4. 10.12
5. 2.3 mv
6. 6.74
7. 5.66
8. 12.75

570

1. 1.102
2. 1.805
3. 1.805
4. 1.9 mv
5. 1.807
6. 1.803
7. 6.63
8. 1.805
9. 1.804
10. 4.72
11. 4.72
12. 1.805
13. 14.9
14. 1.805
15. 1.805
16. 0.920

3101

1. 13.56
2. 6.79
3. 3.5 mv
4. 6.79
5. 6.53
6. 6.99
7. 6.75
8. 12.83

[murdog47]

Bought from ebay seller POLIDA.

[Scruffie]

Bought from ebay seller POLIDA.

Have you tested them in anything else?

Your voltages look reasonable... so you probe up to Pin 3 of the first MN3005 and on the output... whine?

You are trying to bias it while probing the output yeah?

[murdog47]

Have not tried them in anything else. Dont have anything to put them in. Yes and yes on the wine and biasing.

[Scruffie]

That complicates matters they could be fake or dead having come from ebay...

Could be another issue though.

Hard without a scope or some way to verify the chips, but a photo of the chips might be of some minor use for guesswork.