Repairing a pair of Beats by Dr. Dre Studio

Someone recently came up to me asking whether I could repair his headphones. I was expecting it to be the typical bad connection on the jack, but it turned out to be something more difficult.
Thrilled by the challenge I accepted the offer of repairing his headphones and I took them home.

The problem turned out to be more difficult to solve than I anticipated, but I did end up solving the initial problem. However after came to the conclusion that the right driver is messed up, most likely irreparably.

The Beats by Dr. Dre Studio have a built in amplifier with equalization circuit. The problem however was that this circuit refused to turn on, unless it was at a specific point pushed very hard. Since the signal has to pass through the amplifier, this meant that the headphones simply didn't work at all.

The first challenge was disassembling the headphones.  It took some force to get the pads of, but luckily it was only screws after that.
A picture of one of the earpieces with detached pads.
The circuitry is situated behind drivers.

I figured this was a problem caused by a short circuit of the battery somewhere in the circuit, so I checked continuity almost everywhere. After about three quarters of an hour I gained certainty that this was not the cause of the problem. I took me longer to get to this conclusion as I was confused about two little wires that were disconnected. I could not find any purpose for them whatsoever, so I decided to just ignore them.
Mysterious wires without any purpose. What on earth are
they doing there?

Maybe the battery isn't attached in the first place?
Yep. I was unable to detect a significant potential difference anywhere in the circuit, despite the fact that the battery connections looked fine. I found a consipicous wire which did not measure continuity with it's respective battery terminal, so I smashed a blob of solder on there, and the power led of the amplifier lit! It couldn't be that simple, right?

The loose wire on the battery terminal

Yay! The LED lit. I felt like a real winner.

I Then reassembled them to test whether they work now. When I connected them to my iPod I found that the right channel was very soft and distorted. This new problem seemed much harder to solve, and it turned out I was right in making this presumption.

I first thought that the problem would be the connectivity of the right driver with the circuitry, especially the amplifier. I checked almost every little wire with my multimeter, and nothing came up. I then resoldered all the wires related to the amplifier and drivers, but still no luck.
After a few hours I gave up on trying to fix the amplifier (I was convinced this was the problem at the time) so I decided to completely bypass the amplifier.
This also took me a couple hours, as I just couldn't get the right channel to be connected. But eventually I noticed that the right channel was still connected across the amplifier. I placed a jumper across the amplifier PCB and the right driver made sound once again, and yet again I felt victorious.

The jack is rewired such that the amplifier is bypassed.

However after reassembling again the problem with the right channel was exactly the same. The only option left was that the driver it self is the thing that's damaged.

How this is caused is still a mystery to me. Maybe the disconnected battery terminal might have somehow caused a DC current in the driver causing deformation. Otherwise the pushing on the driver that made the LED turn on according to the owner might have deformed something.
I am however fairly sure that the issue is caused by a driver deformation, as the sound is very distorted. A loss of strength in the magnetic field or a loose wire would not cause this.

1 opmerking:

  1. Your Studios are fake. The circuit is a dead giveaway.