Solved: Urbanears Stammen Speaker not working / repair

I share how I repaired my Urbanears speaker “stammen”.

Symptoms:

When power cord is plugged in the device does not light up/start.

Initial diagnosis; swap power cord and measure if the power cord is providing AC voltage accordingly.

Next step is to disassemble the speaker to take a look inside.

This particular speaker can be accessed from two sides. The bottom and the side. On the bottom are 6 screws hidden under the supporting cushions and caps. On the side of the unit is a squar panel that has been inserted into the side of the speaker. This panel is glued in place with lots of sticky tape. Careful prying finally made a gap to insert a flat stirdy spudger.

In the image you can see how this panel is attached to the speaker.

Inside we have a ac to dc inverter and a main rectangular board screwed on the inside wall of the speaker.

After checking the inverter output voltage to be 18 Volt DC, assumed is the DC power source most likely functions properly.

Removing the main board from its position reveals the details. The main board consists of 2 board stacked together.

To diagnose the main board, use a multi meter in continuity mode and check all caps if they short to ground.

After a brief inspection it was found that in one corner of the lower main board a number of caps are shorted to ground.

Since there is no thermal camera available, a voltage injection tool was used to find the component responsible for the short.

Unfortunately the rather cheap voltage injection tool turns itself off to protect against high current draw. This means manual checking is required. Each component that was shorting to ground was removed one by one from the board by using a hot air station with remeasuring in between each removal. After removing and replacing around 10 caps to the board it was noticed that a specific component was causing the short.

This component is a DC - DC buck converter in a SMD format( DDA Package, 8 Pin SO PowerPad) called TPS54335A from Texas Instruments.

The function is to reduce the incoming 18V to a lower voltage suitable for the main processing chips.

When this component was removed the short disappeared.

You can order this component online.

After replacing the buck converter, the speaker immediately started working again.

Note: it may be possible that in your case a different cause is the reason for the speaker not powering on. Yet the steps involved in this post may help to pinpoint the cause of the problem.

Since I couldn’t find any information regarding the repair of Urbanears Speakers (not their headphones) I decided to share this thread for those willing to repair their Urbanears speaker.