Buzzing sound is only sound produced?

[KE8NWH]

Hi there. I've built a kit from uptech, and it works great.

So I bought PCBs for a group buy by following the guide. The only part I had to change was Y1 from the original C156249 https://jlcpcb.com/partdetail/NDK-NX322 ... 07/C156249 to the more expensive but seemingly the same pinout C160453 https://jlcpcb.com/partdetail/171833-HS ... 85/C160453

Also JLCPCB had no LT6231's in stock, so I had to get them from digikey and hand solder them. https://www.digikey.com/en/products/det ... PBF/888557

I verified that the orientation of the chip was correct by buzzing out the ground pin with a dmm. I also checked my uptech board, and it matched.

Here is my problem: The audio output buzzes loudly. I've linked a recording. https://www.dropbox.com/s/cgao2jgebpbl2 ... 8.mp3?dl=0

It does not buzz when the board has no bootloader. It does not buzz when the board has a bootloader. It only buzzes after firmware is flashed.
It buzzes the same on all frequencies and bands. It even buzzes when no RF board is attached. There is no change.

I can make the buzz quieter by turning down the volume. I can change the shape of buzz by switching from USB to LSB or CW. And changing the filters also affects the buzz. I can hardly be heard when CW is choked all the way down to 50hz.

It buzzes on 13.8v battery power, and it buzzes on 5v usb power. It buzzes when there is no OLED attatched. It buzzes when the only installed parts are LT6231, the 3.5mm jack, and the ISP header. It does not buzz when the LT6231 is not installed, it is quiet.

Any ideas on whats wrong? I bought 50 boards, and I've flashed 4 so far with identical results. I'm gonna try finding a solution before moving on. Hopefully it doesn't involve replacing the 27Mhz Y1...

Thanks in advance!

-Tom

[dl6sez]

Hello OM,

yes propably this: have a look at your Si5351 (or MS5351) pins.
I once had nearly the same "motor boat sound" problem when one pin of the DDS was not really soldered.

73 de Chris

[KE8NWH]

Thanks for the response!

I reflowed the Si5351 chip on a couple of these boards, at your recommendation. And unfortunately that didn't fix the issue

I even poked the pins with a toothpick, no change.

Any other thoughts or suggestions?

[storyofyouandme]

Replace 3253

[dl6sez]

Hello OM,

you can measure output clock clk_0 and clk_1 with an oszilliscope and see if there is a 90° phase difference. Do this on a frequency around the middle of shortwave bands. I would tune to 10MHz or 14MHz.
It seems that your Si5351 could have been damaged. If you have one, you can simply swap it although it is not super easy to swap...
and think about to earth your solder iron tip, we have winter time with always a little bit more problems due to ESD.

73 de Chris

[KE8NWH]

Replace 3253

Thanks for the suggestion!

Unfortunately I don't have any spare 3253's around, so I reflowed the solder on that chip on 3 boards, and this has not solved my problem unfortunately.

I could try and swap the one from my working board onto a non working board, but I'll need to get my hot air gun out of storage first.

Do you have any other suggestions for me?

[KE8NWH]

Hello OM,

you can measure output clock clk_0 and clk_1 with an oszilliscope and see if there is a 90° phase difference. Do this on a frequency around the middle of shortwave bands. I would tune to 10MHz or 14MHz.
It seems that your Si5351 could have been damaged. If you have one, you can simply swap it although it is not super easy to swap...
and think about to earth your solder iron tip, we have winter time with always a little bit more problems due to ESD.

73 de Chris

I do not have an oscilloscope unfortunately, though I may be able to borrow one.
Do you think that Si5351 could be damaged on all 50 boards? I have only tested 5 boards, and all of them have this buzzing.

At you recomendation, I have taken a fresh board out of the JLCPCB box, carefully grounded myself and my iron, soldered on the LT6231 chip, an ISP header, and a 3.5mm jack on audio output. I still have the same buzzing unfortunately. Could it be anything else? Do I need to file a claim with JLC PCB?

Thanks for all your help.
-Tom

[dl6sez]

Hello OM,

no i don't believe this can happen on all 50 boards.... didn't git you right it is on more than one pcb....
but as i understood you checked with battery and 5V power from usb
so for me the well known cause is a bad Si5351.
I would check all components on the pcb that could be visualy inspected, ic type and orientation, resistor values....
Have you checked the pcb at a different place because maybe you have a nearby electromagnetic injection of a very strong field and all is okay...

73 de Chris

P.S.: To prove to your chinese supplier you will have to find the reason with an oscilloscope is best.

[KE8NWH]

Hello OM,

no i don't believe this can happen on all 50 boards.... didn't git you right it is on more than one pcb....
but as i understood you checked with battery and 5V power from usb
so for me the well known cause is a bad Si5351.
I would check all components on the pcb that could be visualy inspected, ic type and orientation, resistor values....
Have you checked the pcb at a different place because maybe you have a nearby electromagnetic injection of a very strong field and all is okay...

73 de Chris

P.S.: To prove to your chinese supplier you will have to find the reason with an oscilloscope is best.

Thanks for the input!

I visually inspected the boards per your instruction. Everything seems to be in order. I can't find any chips the wrong orientation or bad values.

I painstakingly swapped the 5351 from my working board, onto a bad board. The buzzing noise remained on the bad board. When I swapped the 5351 back to the working board, the working board still works fine.

This leads me to believe that somehow, it is not the 5351. Do you have any other suggestions?

[DL2MAN]

I think it's time for some audiovisuals....
Please post a video of your problem.
Please make as high resolution as possible pictures of your boards.

73 Manuel DL2MAN

[KE8NWH]

I think it's time for some audiovisuals....
Please post a video of your problem.
Please make as high resolution as possible pictures of your boards.

73 Manuel DL2MAN

Thanks for your response!

Here are some pictures https://photos.app.goo.gl/xvUYdtwL7eQp6whw5

I have two videos uploading, I will update this post when they have finished.

Edit: Here are the videos, please let me know if you need more! https://photos.app.goo.gl/XSWyzQJkjMcGRPAz9

-Tom

[DL2MAN]

OK, after seeing this, I´m pretty sure, you didn´t do the OLED Mod....
https://youtu.be/VVGBapoCUls?t=557
Better visibility also here:
https://youtu.be/hLCFsNNDZUg?t=464

73 Manuel; DL2MAN

[KE8NWH]

OK, after seeing this, I´m pretty sure, you didn´t do the OLED Mod....
https://youtu.be/VVGBapoCUls?t=557
Better visibility also here:
https://youtu.be/hLCFsNNDZUg?t=464

73 Manuel; DL2MAN

Thanks for your response! I too thought that it might be the OLED somehow. But unfortunately I get the exact same buzzing even when the OLED is not installed.

Additionally, I did the OLED mod to all of the screens that I have prepared for these radios. Here is an example: https://photos.app.goo.gl/D3DVZ7RbmA8pVH9A7

Do you think it could be something else? The only thing different from the stock design, is the 27mhz Y1, instead of the original C156249 to the more expensive but seemingly the same pinout C160453. Links are in the original post of this thread.

All of my parts are genuine to my knowledge. I bought everything from the recommended sources, and didn't skimp anywhere.

Thanks for your help thus far!

-Tom

[dl6sez]

Hello OM,

i think the only possibility to get closer to the error/bad ic will be using an oscilloscope and start from DC voltage (voltage ripples maybe made by 78L05) than to Si5351 clk 0 and clk 1, than have a look at Tayloe mixer 74cbt3253 input to output and LT6231 signal inputs to outputs....
And at last, we know that actual void specs for Atmega328P are only clock up to 16MHz and you still have an Atmega328P in circuit doing with 20MHz clock. I don't believe this is the cause but we should use Atmega328PB in the future only, it can do 20MHz clock also today in the void specs.
Sorry i have no other idea how to get closer to the error.
Your pcbs look really good. Only one solder joint looking not really nice at one of the Tayloe mixer 100nF Cs C25 to C28, but don't believe this is a problem

73 de Chris

[KE8NWH]

Thank you all very much for your help thus far.

I am definitely getting over my head at this point, with the oscilloscope being my next option. But I will keep moving forward, I've been needing to learn it to use one.

How fast are the signals we're talking about? How much resolution should my oscilloscope have? I will look into borrowing or buying one.


Manuel, would you be interested in looking at one of these boards? Not just for me, but for everyone else? It seems like a really confusing problem, and if the next person can avoid it somehow, that would be good.
I will gladly ship one to you, I'll pay all fees and you can keep the board. I will of course continue to search for my own answer as well. Please let me know.

-Tom
KE8NWH

Edit: I just had a thought, Chris you spoke of the atmega potentially being a problem.

I'm not flashing my bootloader with an Arduino, as I couldn't find mine. So I built an adapter for my USBasp that I use for flashing attiny85's.

I'm still using AVRdudess, and I kept the baud rate and fuses the same as the instructions, but obviously selected USBasp from the programmer drop-down, as well as "USB" for my port.

I checked and the fuses are still burning correctly and there are no errors. Also obviously it works as far as giving me the the serial number on the OLED and allowing me to flash the firmware over the truSDX USB port.

Is it possible that I stumbled into some strange bug? Or that I misunderstood how flashing works?

Please advise.

Thanks again.

[dl6sez]

Hello OM Tom,

i have also used my USBasp for flashing bootloader, so there is now no problem when afterwards the software runs as it was for your (tr)uSDX.
I don't think it has something to do with software.

73 de Chris

[KE8NWH]

Hello OM Tom,

i have also used my USBasp for flashing bootloader, so there is now no problem when afterwards the software runs as it was for your (tr)uSDX.
I don't think it has something to do with software.

73 de Chris

Aww bummer I was hoping for an easy fix haha. Ok thanks.

Tom

[DL2MAN]

Hi Tom,

Yes, you can send one, and I will look at it. The Adress you find on my Imprint Page (Impressum).
I´m pretty sure it´s something really simple. And if we found it and you fixed it, we might even use this rig to get your approval status, so you´re an official source.

73 Manuel; DL2MAN

[KE8NWH]

Hi Tom,

Yes, you can send one, and I will look at it. The Adress you find on my Imprint Page (Impressum).
I´m pretty sure it´s something really simple. And if we found it and you fixed it, we might even use this rig to get your approval status, so you´re an official source.

73 Manuel; DL2MAN

Thanks! The package went out this morning, 2/21/2023.

-Tom

[reytek79]

I think it's time for some audiovisuals....
Please post a video of your problem.
Please make as high resolution as possible pictures of your boards.

73 Manuel DL2MAN

Thanks for your response!

Here are some pictures https://photos.app.goo.gl/xvUYdtwL7eQp6whw5

I have two videos uploading, I will update this post when they have finished.

Edit: Here are the videos, please let me know if you need more! https://photos.app.goo.gl/XSWyzQJkjMcGRPAz9

-Tom

Friend, I don't know if this is your case, but I already had problems with solder flux that was conductive, try to clean that flux over there in the U9 region

[DL2MAN]

Thanks! The package went out this morning, 2/21/2023.

-Tom

Mainboard arrived !
Please look at your emails for further information request.
73 Manuel; DL2MAN

[KE8NWH]

Friend, I don't know if this is your case, but I already had problems with solder flux that was conductive, try to clean that flux over there in the U9 region

Sorry for the late reply. Thanks for the suggestion! I should've cleaned the flux off of this board before I took the picture, but I did test several boards after washing the flux several times with 90 isopropyl and a toothbrush, and unfortunately there was no change.

Thanks again! I hope we can get this figured out.
-Tom

[KE8NWH]

Thanks! The package went out this morning, 2/21/2023.

-Tom

Mainboard arrived !
Please look at your emails for further information request.
73 Manuel; DL2MAN

Thanks Manuel!
I did see you email and responded that day with the requested information. Hopefully you got it
Seems it might be a tough nut to crack, hopefully we can figure it out. I haven't had any time to investigate further these past couple weeks.

Thanks again!
Tom

[DL2MAN]

I did see you email and responded that day with the requested information. Hopefully you got it

No, I did not get it. I also went through my spam folder..... No Mail from you. Can you please send it again ?
73 Manuel, DL2MAN

[KE8NWH]

I did see you email and responded that day with the requested information. Hopefully you got it

No, I did not get it. I also went through my spam folder..... No Mail from you. Can you please send it again ?
73 Manuel, DL2MAN

Sorry I didn't see this response earlier. I have resent the email just now at the time of this post. Hopefully it finds you!

-Tom