Not truely "random"

[rafael-azevedo]

I was able to calibrate the turing machine so the locking feature works. The issue I am having is that I always get a similar sequence a small ramp up from 0 in steps and then it holds the highest value set by the trim pot for a while and repeats. Now it does this randomly , but I never get step down or anything of that nature.

[rafael-azevedo]

Adding two videos of it working. In this one with it in the unlocked position you can see if always hit the same voltages https://youtube.com/shorts/sOzEx5lxdU0?feature=share

a video of it with a "scope" view

https://youtu.be/H7w2LE5eGns

[rafael-azevedo]

posted pictures here of the build https://modwiggler.com/forum/viewtopic.php?p=3995928#p3995928

[rafael-azevedo]

bump

[TomWhitwell]

The pictures look OK, was this built from a Thonk kit?

One think to try would be to swap the two 4015 shift register chips and see if the behaviour changes

[rafael-azevedo]

I am pretty sure its a thonk build. I picked it up second hand. It was working as expected before shipping. I swapped the two chips and the behavior stayed the same.

[Thonk-Steve]

Hi Rafael, I think you should return it and get a refund or insist that the seller repairs it for you. Regards Steve Thonk

…

On Fri, Jul 14, 2023 at 2:03 PM Rafael Azevedo ***@***.***> wrote: I am pretty sure its a thonk build. I picked it up second hand. It was working as expected before shipping. I swapped the two chips and the behavior stayed the same. — Reply to this email directly, view it on GitHub <#202 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAKXH6EST7GFYOAAO6DKEULXQE7SFANCNFSM6AAAAAA2F65DNI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[rafael-azevedo]

Ya I worked out a deal with the seller already. Just trying to see if I can troubleshoot whats up. I ordered new IC chips if those don't work I'll just do a new build haha

[Thonk-Steve]

Ok glad to hear that, there are some sellers who seem to think a buyer should inherit their build problems :)

…

On Fri, Jul 14, 2023 at 3:17 PM Rafael Azevedo ***@***.***> wrote: Ya I worked out a deal with the seller already. Just trying to see if I can troubleshoot whats up. I ordered new IC chips if those don't work I'll just do a new build haha — Reply to this email directly, view it on GitHub <#202 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAKXH6HUVQGPNPVX3PMTNBDXQFIGTANCNFSM6AAAAAA2F65DNI> . You are receiving this because you commented.Message ID: ***@***.***>

[rafael-azevedo]

Any other recommendations on troubleshooting before I give up. I've replaced all the ICs outside of the DAC and the noise trimer pot and its still exhibiting the same behavior

[rafael-azevedo]

Seems I have isolated the issue. The voltage out is not matching the bits in the shift register. If I understand correctly they should be multiples of 0.033v but I am getting 0.3V with 1 bit in the first position video attached explaining

https://youtube.com/shorts/DnVebaOAveQ?feature=share

[TomWhitwell]

Maybe something wrong around the resistors in the op amp that scales the output? Maybe if R26 was 50k or 500k you'd see this behaviour? Just a guess, I've never seen this before, and it would only explain incorrect voltage output, not incorrect sequences of bits.

[rafael-azevedo]

Yup looks like there was an incorrect resistor for R26 I replaced it and had to jump it to p1 of the TC074. Now I am getting a new behavior where sequences longer then 5 don't work as expected https://youtube.com/shorts/4pj9n4bUo6s?si=-Ana2UskU1RuRxdt