MUSIC MAKER SHIELD - HISSING NOISE Moderators: adafruit_support_bill, adafruit

[Zlshep]

Hello, I have made a set of speakers that play music using an Arduino Uno with the Adafruit Music Maker MP3 shield. It works great but recently, after being switched on for a while, it will start to make a continuous hissing noise. I've tried recharging the battery, and if I adjust the voltage then the hissing stops but it will then start again and I adjust the voltage the other way and it stops again. I don't really know what is happening or why. It was working fine for months and now this. Also when I plug in using the USB directly to the arduino the hissing stops. Any suggestions? It's getting on my nerves because whenever I adjust the voltage I then have to adjust the potentiometer on the LCD screen to set the contrast again.

[mikeysklar]

We have a related thread that recommends earth grounding.

viewtopic.php?f=19&t=131464

[Zlshep]

@mikeysklar Thank you, I can try that (although I'm not sure how, and I can't seem to find any info online).

The issue I have is that it runs fine for hours, I'll be sat here at my desk working and playing music and then suddenly the hissing will start. And it won't stop until I turn it off for a while, or if I plug it in via USB (but then when I unplug it it starts again).

[mikeysklar]

The hiss coming on after hours of playing could be one of three possible causes. Let me know if you think of others.

1) The USB battery is sagging and the lower voltage is causing noise? I would dismiss based on your last note about plugging in via USB power source still has a hiss.

2) The chip is overheating? The one near the terminal blocks for speaker connection. This is a part that was changed due to availability and could be a source of hiss.

3) Something in your environment has changed. Your own physical proximity to the player or something else that can effect grounding.

I feel like the most likely scenario is #2 since you can reliably play for a long duration. You could measure the temperature of the processor even add a heat sync or fan to see if that resolves it.

[Zlshep]

The hiss coming on after hours of playing could be one of three possible causes. Let me know if you think of others.

1) The USB battery is sagging and the lower voltage is causing noise? I would dismiss based on your last note about plugging in via USB power source still has a hiss.

2) The chip is overheating? The one near the terminal blocks for speaker connection. This is a part that was changed due to availability and could be a source of hiss.

3) Something in your environment has changed. Your own physical proximity to the player or something else that can effect grounding.

I feel like the most likely scenario is #2 since you can reliably play for a long duration. You could measure the temperature of the processor even add a heat sync or fan to see if that resolves it.

Thank you for your quick reply. So re 1: my first immediate thought was battery issues. I have a potentiometer to reduce the amount of voltage the battery gives to the arduino, but when it's hissing I can turn it down and the hissing stops, and then when it starts hissing again I turn it back up and it stops again. This makes me think it's less likely to be a battery problem. But it is very possible. The thing is, the play duration of the speaker has not noticeably reduced. The battery pack lasts for ages and I've not had any performance issue so it doesn't feel like that.

Re 2: Would this come on over time? I had six months or so of this working perfectly fine and now this issue. However, heat would be a good explanation as the longer I leave it off for, the longer it goes without hissing when turned back on. Plugging in via USB stops the hissing immediately though, which doesn't seem like a heat problem. A heat sink or small low-voltage fan sound like good and cheap things to try. Currently it is completely enclosed in a 3D printed case, so I can definitely see how heat would become an issue. Perhaps I need to add some vents too. Incidentally I did open the case earlier to have a look at the grounding thing you mentioned and the hissing stopped so the more I think about it the more I think it definitely must be that. Would it be possible for this to become an issue after several months of perfect functioning?

Re 3: It really doesn't feel like this is the issue because it's always sat here on the shelf next to my desk where I work. Nothing has changed in my environment really.

If you're interested in seeing it, it's here: https://youtu.be/9J762zsPwB4 The arduino and sound board are in the right-hand speaker as you look at it. It's quite a long cable from that to the left speaker, up the stalk and back down, but it's both that hiss so I don't feel like that's the issue either. I will try some heat dissipation techniques, thank you!!

[mikeysklar]

Nice build. The cherries and controls are really great. Well done.

The heat seems like the most likely cause to rule out right now. The soldering can become compromised if a chip is really cooking itself, but there is no reason to assume things are that bad as of yet. Maybe look for a low profile heat sink that fits your enclosure.

https://www.adafruit.com/?q=heat+sink&sort=BestMatch

consider a small 5v fan:

https://www.adafruit.com/product/3368

[Zlshep]

Nice build. The cherries and controls are really great. Well done.

The heat seems like the most likely cause to rule out right now. The soldering can become compromised if a chip is really cooking itself, but there is no reason to assume things are that bad as of yet. Maybe look for a low profile heat sink that fits your enclosure.

https://www.adafruit.com/?q=heat+sink&sort=BestMatch

consider a small 5v fan:

https://www.adafruit.com/product/3368

Hi, thank you. I tried a tiny 7mm heat sink but that just seemed to make the problem happen much quicker. Also when it starts hissing I touch the chip next to the terminal blocks and it doesn't feel remotely hot. But also, touching it makes the hissing stop instantly. Also, blowing into the compartment seems to stop the hissing sometimes but not others. As I am writing this, it's playing and hissing, and I have the back cover open and blowing directly on the chip did nothing. I have no idea what could be causing this. It's driving me mad!! I'm not keen on installing a fan unless absolutely necessary but judging by me blowing on it having no effect it seems unlikely. The heat sink is removed but the chip does not feel hot at all.

[Zlshep]

OK update, it seems touching the metal chip legs with a screwdriver seems to stop and/or start the hissing noise. It's causing a noticeable interaction. The screwdriver has a rubber handle so I'm not grounding it by touching it I don't think. Any further suggestions? Thank you for your help so far!

[Zlshep]

Right further update - every time I touch the +6dB connection the hissing instantly stops. I can't find anything that reliably starts the hissing, but touching the arrow-shaped segment of the +6dB makes it stop immediately, and every time. I can touch it with my finger or the screwdriver and it immediately stops. The +6dB has not been soldered. Touching the other end of this connection does nothing. I feel like we are getting somewhere???

[Zlshep]

It definitely seemed to be somehow linked to the +6dB, or what's at the other end of that. When the hissing was occurring I went over the whole circuit touching various components and metal contacts with my finger and with a screwdriver and nothing happened at all, except for when I touched the +6dB connection. Specifically the bit shaped like a house. Touching the other end of the +6dB connection did nothing as well. So I have decided to solder over that connection and so far the issue seems resolved. I don't know if it grounds it somehow or something? I'm by no means an expert on this. But until next time I guess!

[mikeysklar]

Good job narrowing it down the 6db connection. Can you take a photo of the area of the PCB you resoldered? I know the 6db jumper, but am not sure which part you had to rework.

[Zlshep]

Good job narrowing it down the 6db connection. Can you take a photo of the area of the PCB you resoldered? I know the 6db jumper, but am not sure which part you had to rework.

I didn't really "rework" it, I just soldered that connection to "activate" the optional +6dB feature. It's soldered over now and seems to be running smoothly. I've not had to repair anything on the board. I don't really know much about electronics, this is only my second Arduino project and the first one using the Music Maker shield. Do you still need a photo?

[mikeysklar]

No need for a photo. Thank you for the clarification on the modification.