Aion FX Maelstrom Bass Drive build issues

[scooterbus]

Hello. This is my first post to this forum. It's also my first pedal build, but while this is my first pedal its not my first attempt at soldering or my first build. I have previously built the London Power Bass pre amp kit, and I have years of soldering experience working with LED tape at work.

The build went fine. I kept it organized and in general felt like it went together good. I had a few issues but nothing I couldn't fix. One of the IC sockets wasn't seated all the way against the board, and I was able to remedy that. One the IC chips (IC4) was installed backwards initially, I popped it out and re oriented.   

It does not sound right. I pulled it apart and inspected. I ended up reflowing some of the points and cleaning things up a bit. I also made sure to re seat IC3 after fixing its socket. I also remeasured voltages on the IC chips.

IC3 is reading 9.2 or so volts on pins that should be 0. Pins 5, 7, 9, 11, and 14 all should be 0 but I am reading around 9.2 volts on each. Everything else reads as it should.

It does not sound correct. Please watch the video's. Hopefully I have articulated the issues I am having. I'm pretty stumped. I think I have everything correct but clearly something is not.





















First Video, sound check -

Second Video, explanation -

Third Video, sound check after "repairs" -

Thanks for any help.

[idy]

Following the schematic, pins 5,7,9,11, 14 are all tied to VA, the supply voltage, 9v. They are unused inverter inputs which good practice says to tie to either ground or 9v. I think this came up before. An earlier version tied them to ground, Aion has changed their practice. This is not a problem.
The inverter that is being used shows close to correct voltages, but that may just be a properly biased dead chip...
Maybe someone else can say if putting it the wrong way would kill it. This was a kit so you don't have another one lying around...
The voltages on the two opamp chips look good, as do those on the FETs. 

[aion]

I do wonder if IC3 is damaged. For the kit version (PCB labeled v1.1) pin 5, 7, 9, 11 and 14 should actually read 0V. As idy said, the chip doesn't care whether it's 0V or 9.21V, but it sets off my trouble sensors. Along with that, it should not be possible for pin 5 to be 0V but 7, 9, 11 and 14 to be 9.21, since all five pins are directly connected. So there is probably a measurement error someplace, but we could also be dealing with a damaged chip from putting it in the wrong way around.

Here's something I wrote a few months ago for the most recent round of kits:
https://aionfx.com/app/files/docs/kit_troubleshooting_guide.pdf

I haven't gone back and linked it to earlier kit docs like the Maelstrom yet, but it's meant to be universal for all the kits.

[scooterbus]

it should not be possible for pin 5 to be 0V but 7, 9, 11 and 14 to be 9.21, since all five pins are directly connected. So there is probably a measurement error someplace, but we could also be dealing with a damaged chip from putting it in the wrong way around.

I double checked. When I first measured voltages and recorded them I didn't realize that the PDF skips pin numbers so in image 6 it shows the recorded voltages wrong. I re-measured later after realizing this and recorded them in the upper right part of the PDF that shows the 16 pin chip, its the last image. I just double checked and those recorded voltages are correct so I am seeing 9+ volts on pins 5, 7, 9, 11, and 14. I can/will order another chip. Should I replace them all? They are cheap enough.

Here's something I wrote a few months ago for the most recent round of kits:
https://aionfx.com/app/files/docs/kit_troubleshooting_guide.pdf

I haven't gone back and linked it to earlier kit docs like the Maelstrom yet, but it's meant to be universal for all the kits.

Before I posted this I did a search in this forum for this kit specifically and found a post one someone else's build. That caused me to go back and re-flow solder points. Ive basically done everything Ive read as far as trouble shooting goes so I guess I will order new chips. I did instal one resistor and one film cap in the wrong spots accidentally and had to desolder/remove and correct. Maybe I damaged the board doing this?

I guess my other other recourse (if the new chip doesn't fix) is to order a new board and the parts for it (resistors/caps) and rebuild the main board to try and save the rest of the kit?

[idy]

First thing is to try a new inverter chip. The others appear to be working, so I wouldn't mess with them.

Check continuity on any pads where you had to remove and replace something. Fixing that is usually easy but a little ugly, a bit of component lead bridging a broken trace. Sometimes the little "eyes" that plate the holes come loose.

[scooterbus]

First thing is to try a new inverter chip

I ordered a new chip for the IC4 socket. Thats the one I had flipped around. Do you think I should have ordered a 16 pin for the IC3 socket too? Either way, a new 8 pin is coming so I can try that and see if that changes anything.

[aion]

A couple things after digging in on my end -

1) It seems that there were a few PCBs sent out that had pins 5/7/9/11/14 tied to the positive supply instead of ground. So the reading of 9.21V instead of 0V on those pins is plausible. But, when doing it this way, it's best if they are exactly the same as pin 1, which means R30 needs to be jumpered instead of a 100R resistor. Can you try doing this? (All it does is undo some extra power filtering that is not in the original B3K, it won't change the circuit at all.)

2) IC4 is likely not the problem since TL072s can usually survive being inserted wrong, but I included one of each IC1-4 in the replacement package just now. After you've jumpered R30, try swapping out all of the ICs, but particularly IC3 and IC4.

3) I would guess that neither #1 or #2 will fix the issue since I don't think they are related. I would definitely suggest what idy said just now, focusing on the spots where the components were desoldered, and looking for shorts or visible damage. But, if you still can't get it to work then let me know, we'll get it up and running one way or another.

[scooterbus]

1) It seems that there were a few PCBs sent out that had pins 5/7/9/11/14 tied to the positive supply instead of ground. So the reading of 9.21V instead of 0V on those pins is plausible. But, when doing it this way, it's best if they are exactly the same as pin 1, which means R30 needs to be jumpered instead of a 100R resistor. Can you try doing this? (All it does is undo some extra power filtering that is not in the original B3K, it won't change the circuit at all.)

I should remove the resistor and jumper with buss wire, or just hop over the resistor somehow?

I will check the two spots I desoldered... If I remember which ones they were! I was pretty careful and dont recall seeing damage to the pads but Ill check.

[aion]

I should remove the resistor and jumper with buss wire, or just hop over the resistor somehow?

Whichever seems easiest. As long as the pads are connected then the resistor is out of the circuit. I usually use a clipped resistor lead for jumpers. If it was me I would piggyback on the existing resistor, since you can go in from the top without removing the board from the enclosure. But it can be tricky to get a good joint on the pads without a hole to work with.

[scooterbus]

I should remove the resistor and jumper with buss wire, or just hop over the resistor somehow?

Whichever seems easiest. As long as the pads are connected then the resistor is out of the circuit. I usually use a clipped resistor lead for jumpers. If it was me I would piggyback on the existing resistor, since you can go in from the top without removing the board from the enclosure. But it can be tricky to get a good joint on the pads without a hole to work with.

I dont mind taking the board out. I'm using a fairly thin tip on my iron and I may be able to get in there and solder it. I also have actual unshielded buss wire, but I should have some cut leads as well.

I'll give it a shot. If I feel like I cant get in there without damaging anything I'll try from the top but its not that big of a deal to pull the board and de solder the resistor.

[scooterbus]

I received the new chips and installed them, I also removed the R30 resistor and bussed it. It did not fix the issue but now I have new ones! Mostly a noise issue with I touch the high switch. If its in the middle or off to the right side (I believe, cand remember at the moment) it makes this noise. Otherwise there is not much change in the tone. 5/7/9/11/14 now all read 9.2V.

I looked for any other physical damage but couldn't find anything that stood out to me.

I do remember putting the wrong resistor into R24 and its the most egregious looking one. It does read 4.5V either side of it though. I also belive I accidently swapped a 220N with a 2N2 and I think it was putting C20's cap in C13's spot, then removing it and soldering to the correct spot. I dont remember where I put R24's resistor originally.







Here is a video of result.