Order Number: 696105
Product Name: F405te
Brand: Matek Systems
Although ordered and delivered last July, I have only just got round to using the flight controller board. this has been wired up correctly to the GPS unit. However, when a 3 cell Lipo is connected, the flight controller emits a loud tone, although the LEDs appear to be setting correctly. When a 4 cell Lipo Is connected again it’s working correctly, but there is no tone.
This doesn’t seem very good as I understood the voltage range is from a 3 - 6 cell.
I would appreciate your thoughts and comments.
I have tried two different sized Lipo cell counts
That is a very strange issue as the board itself does not have any buzzer so should not be making any sound.
May I ask if you checked the FC before soldering anything as per our guide - How do I test my new Flight Controller? (and why it’s important)
The next thing would be disconnect everything from your FC and power it up via USB only and see if it works ok via the PC software (betaflight/inav), and if so then only connect the battery and see if the issue is the same.
Then do a visual inspection of the board to see if you can notice any issues with solder splatter, or damaged components etc… (if you are not sure, please upload an image of the top and bottom of the FC and we can also check).
This will hopefully help us to narrow down the cause of the issue so we can suggest the next steps. Given that its past our 6 month warranty we may not be able to issue a replacement directly but will definately try to help figure this out if we can!
Good morning Alex,
Thank you for a very prompt response.
I have tried as you have suggested and the board powers up with no audible sound. Likewise there is no sound when a 4 cell Lipo is connected.
However, the sound appears when a 3 cell Lipo is connected, either a fully charged one at 4.2v per cell or a 3 cell at storage voltage, ie 3.8v per cell.
It just appears to want a 4 cell power supply, I have not tried a 5 or 6 cell so wouldn’t know about that.
Kind regards
Graham
Hi good day Graham,
Thanks for reaching out to us!
I believe that the input voltage regulator is struggling to supply the FC at its lower voltage limit. I had a look at the spec for this FC and I see it is rated for 3-8S. Which is a little unconventional, most FPV FCs are rated 2-6S.
Can you send us some clear images of the top and bottom of the board and I will send these through to Matek and ask one of their engineers to have a look as well.
One last check, could you unplug your GPS/Compass and check if it still makes the same noise on 3s?
Hope this helps.
If there is anything else I can help with please do let me know?
Regards,
David
Unmanned Tech Support
Hi David,
Still the same with the GPS unplugged on 3 cell and ok on 4 cell.
(attachments)
Hi Graham good day,
I would go with my original comment and say its probably the input regulator.
Can you send me some clear photos of the board top and bottom?
Will send those through to Matek, along with the video and see what they have to say.
Hope this helps.
If there is anything else I can help with please do let me know?
Regards,
David
Unmanned Tech Support
Thank you for your thoughts.
I did email top and bottom images and a short video with the GPS disconnected.
Did you not receive these?
Hi David,
I am sending the images again but this time as an attachment just in case you never received them yesterday.
Kind regards
Graham
(attachments)
Apologies Graham, I missed the URL there.
I have sent the photos and video off to Matek and asked for one of their engineers to assist.
As soon as I hear back from them I will update you.
Regards,
David
Unmanned Tech Support
Hi David,
Thank you for your help and support.
Kind regards Graham
Hi Graham good day,
I have spoken with one of the engineers from Matek. My first question was whether or no the product specifications for input voltage were correct. He said they are correct, bu the 12V voltage regulator struggles at 3S voltage.
This was his comment:
It is correct.
for 3S input, the FC can work. but 12V BEC can’t output stable 12V. That is the character of step-down regulator.
It would seem that the FC is working as intended but the regulator just cannot perform at that minimum voltage.
Hope this helps.
If there is anything else I can assist with please do let me know?
Regards,
David
Unmanned Tech Support
Good morning David,
Thank you for your email and response from Matek which is quite interesting.
I also have an identical Matek F405TE Flight Controller which I had to order from another supplier (as you were out of stock at that time) which is using an identical GPS unit but that works fine on a 3 cell with no sounds at all.
It does make me question whether there is in fact an issue with the regulator component on the board that I purchased from yourselves?
HI David,
Do you have any thoughts or comments to make please?
Kind regards
Graham
Hi Graham good day,
I have sent through your comment to Matek and asked for their advice. I do agree with your comment, and have pushed for some speedy resolution here.
I will let you know as soon as I hear back from them.
Regards,
David
Unmanned Tech Support
This sound is likely related to the inductor, a component inside the product that helps regulate power. When the electrical current flowing through the inductor changes, it creates a magnetic field. This changing magnetic field can cause tiny vibrations within the inductor itself, which you might hear as a subtle sound.
Think of it like this: you may have noticed a similar faint hum from some LED light bulbs or larger power adapters. It’s a normal characteristic of these types of electronic components when they are working.
In situations where the input voltage to your product is lower than the voltage it’s set to regulate, the sound might become a little more noticeable. This is because the regulator works harder in these conditions, operating with more frequent switching.
It’s also worth noting that due to slight variations in the components we use, not every product will produce a sound that’s audible.
This sound is completely normal and doesn’t indicate any fault with your product’s performance or reliability. It’s simply a byproduct of the efficient voltage regulation process.
Matek write about this a while ago about thee FCHUB-12S, and they are using this same 12V regulator on the F405-TE
For your information, if you’re interested in learning more about this phenomenon, you might find these external resources helpful:
Why does buck and boost converter cause noise? : r/AskElectronics
Buck converter is making noise - Other Hardware / General Electronics - Arduino Forum
We hope this explanation is helpful and puts your mind at ease. If you have any further questions or concerns, please don’t hesitate to contact us.
Kind Regards
Alex
Unmanned Tech Support
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Good afternoon Alex,
This F405TE is still doing the same thing, ie an audible sound. In the light of what Matek has said, as I use 2 x 5200mAH Lipo packs in series to obtain 10 cell for F3A flying, I made up a connector to obtain the full 18.5v from the balance from one pack and still I’m getting the intermittent audible sound and that’s mid range of the stated input voltage.
I can not but help think that some of the components on the board that I purchased are not up to standard.
Any further thoughts please.
Kind regards
Graham
Hi Graham,
Just to confirm the unit makes a audible noise at 3S, is silent at 4S and again makes a noise at 5S?
Regards,
David
Unmanned Tech Support
Hi Alex,
All the time with a fully charged 3s, intermittent with both 4s and 5s. That’s why although I understand the theory of what Matek is saying, voltage well into the mid range of the input voltage shouldn’t cause any issues unless there is an issue with a component.
Hi Good day,
I have asked for assistance, stating clearly that you are experiencing constant and intermittent audible noise coming from the unit on 3, 4 and 5S voltage.
Hopefully I can get to a resolution here tomorrow. I will update you as soon as I hear back.
Regards,
David
Unmanned Tech Support
Hi Graham good morning,
After many, many emails back and forth, Matek has offer you a replacement on the unit. Would you like a replacement or a refund for the item?
Let me know and I can action that for you.
Regards,
David
Unmanned Tech Support
