Fix for Horrible Hissing from a SANWU HF41 TPA3116 bluetooth 5.0 2.1CH Amplifier/BT Module

Not sure why this one was closed.

My question is about how to modify a board to solve a problem it is experiencing. It isn't about "use of an electronic device" (which was the reason given) nor is it about the other two reasons given at https://electronics.stackexchange.com/help/on-topic

It is about a "specific electronics design problem" (in my case a combined bluetooth and amp board), and according to https://electronics.stackexchange.com/help/on-topic, "pecific electronics design problems" are on-topic.

Can I improve the question in some way?


2 Answers 2


Not sure why this one was closed {...} It isn't about "use of an electronic device"

I understand this situation can be annoying. However you are using someone else's device i.e. that audio amplifier board, as it's something you bought & didn't design.

Effectively, the question is asking people to (a) reverse-engineer that device from the photos; (b) gather enough information to understand what is happening; (c) then suggest where and how to fix the problem.

This type of question is very difficult to answer remotely, without a schematic, datasheets and scope traces (aka oscillograms) - as a minimum - so you will also need to have (and be comfortable using) an oscilloscope. That is why (long ago) the site decided questions on using devices were off-topic, since the required design-level information is not provided to buyers and therefore can't be provided by them as part of the question.

Can I improve the question in some way?

Yes - (a) if you added the schematic for the board, as well as links to datasheets for all relevant devices, especially the Bluetooth SoC in the bottom-left corner of that PCB photo, and (b) confirm that you have an oscilloscope to be able to trace the audio signal & power rails through the board, then the question could become (IMHO) a reverse-engineering question with perhaps enough information to be on-topic.

Unfortunately Amazon Marketplace product pages (and Ebay & AliExpress listings) almost never provide the required level of information for non-trivial boards.

Even then, depending on what initial scope traces showed, it may still be unrealistic to diagnose remotely (there can be lots of iterative work needed e.g. the next step depends on what is seen in scope traces gathered in this step, wash-rinse-repeat, and depends how well-equipped your lab is in terms of what mods you can try etc.). It would likely best be done in chat (so that scope traces & other images could be viewed "inline") and would require lots of commitment, from everyone involved, due to the days / weeks of to-and-fro messages that would likely be needed.

Sorry this isn't what you'll want to hear. It's one of the problems of buying products from Amazon Marketplace / Ebay / AliExpress etc. I do occasionally buy stuff from those places, but I always assume (a) some of the components may be counterfeit; (b) it may not be safe or meet relevant standards; (c) I'll have to reverse-engineer the thing myself, to understand it and (d) I won't get any support for it from anyone else, including from the vendor.

  • 2
    \$\begingroup\$ I agree with this. However, maybe a better close reason would have been "repair", instead of "use of electronics" in this specific case. This would have been less confusing to the user. \$\endgroup\$
    – dim
    Feb 26 at 8:26
  • \$\begingroup\$ @dim - Hi, Re: "maybe a better close reason would have been "repair", instead of "use of electronics" in this specific case". Agreed, I can see that viewpoint. However I also remember an OP arguing when the "repair" closure reason was used on a reverse-engineering question with too little detail, saying that they didn't want to repair it, but wanted to improve it. || Due to the very limited choices of closure reason, we do end up with closures where although closure is going to be the outcome anyway, the specific closure reason text does not fit the situation exactly :( \$\endgroup\$
    – SamGibson Mod
    Feb 26 at 21:11

I voted to close the question. This had the symptoms of "cheap product gives cheap results". No shame in trying to save a buck or two but, as @SamGibson says, you are rolling the dice and sometimes you end up with a dud. For instance, I just bought a horrible HDMI adapter that's going back to Amazon.

Your question was, in my opinion, unanswerable. Or at least it was unanswerable in a way that would satisfy you. It's a new product, so the chances of any component breaking on it are pretty slim and the fix for that would be RMAing it (which, good luck) and the hissing only on Bluetooth meant that it was probably either an implementation problem which is not fixable without redesigning the board or a software problem which is not fixable without immense effort - not realistic for a $22 part.


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