Fixing a pair of headphones

[WarpStar]

First things first, they look like Beats, but I’m pretty sure these are knockoffs. Nonetheless, they sound pretty good, and I picked them up at Goodwill for a steal and love a challenge, so if someone is interested on taking on this electronics mystery with me I’d be incredibly grateful.

Context: I’ve tinkered on and off with consumer electronics for a while now, am okay at soldering and have an okay knowledge of how more basic circuits work. Otherwise, I'm pretty beginner but generally a quick learner and would be happy to try any of your suggestions.

The previous owner attempted to replace the AAA battery holding component with a rechargeable lithium ion battery - only problem was there was no way to charge the battery. Not a huge deal, fixed the headphones to run on AAAs again as they were originally intended. That said, pressing and holding the power button powers the headphones on, but also is the Bluetooth connection button on the board (image at the imgur link below) there is an icon for both the connection functionality and the power around the same button. The headphones power on, work, and sound great when you're holding the button down, but once you let go they turn off. So, it’s a momentary switch with no latch to keep it held down - not ideal.

That said, I’ve tested jumping the switch so it gets constant power without holding the button down, and while the headphones power on, connect to my phone, and work, because it seems the power button and bluetooth button are one in the same, the headphones continue to look for Bluetooth devices and makes a periodic and infuriating beeping sound about every fifteen seconds. Based on the pictures of the board below (pictured with, and without button attached) can anyone figure out what the problem might be? Or point me in the right direction for further tests to run?

Front of the board, with buttons.

Front of the board, with power/bluetooth button removed

Back of the board, held upright with power/bluetooth button side up

 

[rjenkinsgb]

It looks like pretty much all the active circuitry is on the bluetooth sub-board.

Can you get a better photo of that side, so all the details are legible? It may be a standard module with data available; there are quite a few with that general style of construction.

 

[WarpStar]

It looks like pretty much all the active circuitry is on the bluetooth sub-board.

Can you get a better photo of that side, so all the details are legible? It may be a standard module with data available; there are quite a few with that general style of construction.

Ahh that would make sense. Here's a clearer picture of the back of the board:

https://imgur.com/a/SCH8M6Q

 

[rjenkinsgb]

I'm not sure if it's the photo, or the name & part number on the large IC have been inked over / sanded off?
Can you read whats on it?

It may be worth going round the module and reflowing all the joints to the larger board, on the offchance one has cracked.

 

[WarpStar]

I'm not sure if it's the photo, or the name & part number on the large IC have been inked over / sanded off?
Can you read whats on it?

It may be worth going round the module and reflowing all the joints to the larger board, on the offchance one has cracked.

It's pretty faded, but took a flashlight to it and managed to read what it says:

Airoha
AB1510
282381
1343SB

Edit: Googled it, found this document with what looks like a schematic. Not sure what to make of it, but seems helpful: **broken link removed**

 

[rjenkinsgb]

Edit: Googled it, found this document with what looks like a schematic. Not sure what to make of it, but seems helpful: **broken link removed**

That's what you need! If you get the longer data sheet from the link at the bottom, it has examples of the external connections for that BT module.

Page 6 shows the power control options; it looks like either a simple button to ground connected to the WAKE pin, or grounding that via a transistor.

According to the diagram, a press shorter than three seconds should toggle power on or off; if it's longer it assumes a direct on/off switch.

 

[WarpStar]

That's what you need! If you get the longer data sheet from the link at the bottom, it has examples of the external connections for that BT module.

Page 6 shows the power control options; it looks like either a simple button to ground connected to the WAKE pin, or grounding that via a transistor.

According to the diagram, a press shorter than three seconds should toggle power on or off; if it's longer it assumes a direct on/off switch.

Great! So would I be looking to run a wire with a Switch attached from the first lead of the button on the front around to the Wake pin on the Bluetooth board on back so the power goes right to that pin instead of through the Bluetooth bit?

Being completely honest I only partially understand lol.

Genuinely appreciate your help with this, by the way!

 

[WarpStar]

Great! So would I be looking to run a wire with a Switch attached from the first lead of the button on the front around to the Wake pin on the Bluetooth board on back so the power goes right to that pin instead of through the Bluetooth bit?

Being completely honest I only partially understand lol.

Genuinely appreciate your help with this, by the way!

Update: ran a wire from the top left hand lead of the original power button to the WAKE pin, and it does in fact power on the headphones after three seconds. Only issue is, it still makes the beeping sound periodically as if it's searching for a bluetooth signal even after being connected via Bluetooth.

 

[rjenkinsgb]

From the data, a single press of _less_ that three seconds should switch it on in pushbutton mode?

I'm guessing it has some extra electronics linked in, something like the setup in the "NFC" drawing of the data sheet, that causes the button to also activate the bluetooth mode input as well as "wake".

 

[WarpStar]

From the data, a single press of _less_ that three seconds should switch it on in pushbutton mode?

I'm guessing it has some extra electronics linked in, something like the setup in the "NFC" drawing of the data sheet, that causes the button to also activate the bluetooth mode input as well as "wake".

Yeah, it seems as if less than three seconds doesn't do much. After three it comes on, and automatically searches for Bluetooth. Just got some new switches in today so I'll try hooking one up to be sure.

That sounds the most plausible, though. Will play around with it and update you by the end of the night.