Anxiety Disorder Drive – Sound Dies (solved)

[Anonymous]

Hey Everyone,

unfortunately, after having built quite a few pedals before including other GuitarPCBs, I now have to ask for help as I can’t seem to get my Anxiety Disorder Drive to function correctly:

• Directly after connecting to power sound is coming through but it dies out and goes silent rather quickly
• The output stays quiet except for sharp attacks that seem to poke through
• When disconnecting power a short squeak can be heard

Here is a video demonstrating the issue.

 

What I’ve done so far:

• Reflow every solder joint
• Measure 9V on the TL072 between pin 4 (V-) and pin 8 (V+)
• Probing around the PCB with a multimeter but I wouldn’t really know what to do except for connectivity checks
• Swap the TL072 for a NE4558 out of sheer desperation

 

Here are some close ups.
Note that the IN and OUT connection wires are in fact hooked up correctly. They only seem off because they are a little twisted in the pictures.

 

Maybe someone has heard this kind of sound breaking down before and can help me figure this out?

 

Thank you for reading through, any help is much appreciated!
Markus

[Barry]

Is the Diode you are using at D1 a Russian germanium?

I cannot tell for sure, but Russian diodes are almost always opposite orientation as 1N34A diodes, which recently have become very difficult to find.

That would mean that the stripe side is the anode and not the cathode so it would need to be installed in the opposite orientation as the silkscreen which was originally designed using a 1N34A diode. If you check my shop page there is a disclosure explaining this.

There is no difference in quality or tone one way or the other. Verify that it is a Russian diode before desoldering. It looks a lot like the D9E diodes that I sell in my shop but I cannot say for certain. If you verify it is a D9E then desolder carefully so as not to ruin the board pads.

I would also trim the transistor leads a little shorter so you can get a tighter fit in the socket.

[Anonymous]

Oh, well spotted thank you I would never have figured that out!
I’m not exactly sure which model the diode is but I measured it and indeed it was soldered in backwards. I fixed that but unfortunately the issue still remains.

Something else I noticed is it does not matter if I have Q1 and Q2 in place or not, the error description is exactly the same. Maybe I should just order a different set of 2N7000s?

Is the sound being there when powering on but quickly fading a hint for anything else?

[Barry]

I was certain that the backward Russian diode would have been the sole cause of that.

I would check to be sure the diode is fine and you have a good solder joint.

If none of that helps you can give us socket voltages both with and without transistors installed.

 

[Cybercow]

The 2N7000 devices are just for hard clipping. The circuit will work with or without them. It will simply be louder and cleaner without the 2N7000s. D1 is just part of the hard clipping configuration to provide asymmetric clipping. Just make sure it’s oriented properly. If it’s not, it just won’t clip right, but the signal should not be dying out like that if the diode is backwards. Dbl-check that orientation.

As for the dying out, it sounds to me like a cap on the PS line is failing. Do three fast voltage measurements.

First, check the 9v supply at the DC jack when you first power it up. Then measure it again when the signal dies out as demonstrated in your video. Write those down. Both measurements should be about 9v.

Second, check the VB supply (4.5v) at the junction of R12, R13 & C10 when you first power it up. Then measure again when the signal dies. Write those down. Both measurements should be about 4.5v.

Finally, measure the DC voltage between ground and pin 8 of the IC when you first power it up. Then measure again when the signal dies. Write those down. Both measurements should be about 9v.

If the 9v dies out in any of the 9v measurements, remove the IC and test the voltages again. There will be no guitar signal to hear, but the voltage testing without the IC will indicate the IC is bad if the 9v stays at 9v for longer than it take for the signal to die. I’d say about a minute or two between measuring without the chip.

With the chip in and the 9v supply line dies after a minute, C9 may be the culprit.

If the VB (4.5v) supply line dies out after a minute or so, it is likely that C10 is bad. If not, check that R3 is indeed a 470K resistor.

Let us know how that goes.

[Anonymous]

I finally got it to work! Thank you so much.

Measuring VB was what got me in the right direction. The voltage division between R12 and R13 was not working and VB was at 9V.

Turns out R13 did not have a connection to ground. Neither did the ground pin of the neighbouring volume pot. Just by looking at the PCB it is not clear to me where the trace is going so I can’t tell where exactly it broke.

I simply bridged it to ground by wire which is not particularly pretty but whatever works I guess 🙂

Playing around with it for about an hour I actually like it more for its clean to light crunch rather than its high gain side. I think it might actually get a permanent spot on my board for exactly that.

You made me really happy thank you very much for helping me out.

[Author]

Posts