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Amazon Echo Dot 4th Gen Smart Speaker Teardown

Published on Saturday 19 December 2020
Categories: Home Automation |

Amazon Echo Dot Rev 4 Teardown

We previously torn down several Amazon Echo devices including the 3rd gen Dot, 3rd gen Dot with Clock, the Flex, and the Echo Input.  In this teardown we will look at the new Echo Dot 4th generation model which is a smart speaker with the Amazon Alexa service.

The 4th generation Echo Dot is a new model which was announced in September 2020 and released in the autumn, the new design has a round appearance and buttons on the side of the curved section.

In the Box

  • The Echo Dot
  • 240V UK power supply
  • Things to try leaflet
  • Setup instructions
  • Echo Dot terms of use

Top of the Echo Dot

The top of the smart speaker has four buttons, four microphones and an LED ring.  The + and – buttons control the volume; the circle button activates Alexa and the circle with a line through it enables or disables the microphones.

Amazon Echo Dot 4 Box
Amazon Echo Dot 4 Box
The Amazon Echo Dot 4
The Amazon Echo Dot 4

Case Base

The base has the serial number, product logos and certification marks.

On the side is a power input socket and headphone / audio out 3.5mm stereo socket.

Base of the Echo Dot with the power and headphone sockets on the back of the case
Base of the Echo Dot with the power and headphone sockets on the back of the case
The rubber foot removed showing the USB debug header
The rubber foot removed showing the USB debug header

Opening the Case

The cover is held in place using adhesive tape and locator pins.

To open the case first you need to remove the non-slip rubber cover on the base of the echo dot, using a thin knife or some other flat bladed tool.

Under the cover you will find four T5 torx bolts and a recessed six pin header which appears to be a debug or programming port.

Removing the four T5 torx bolts allows you to separate the two halves of the case.

Lower half of the case with LED diffuser ring
Lower half of the case with LED diffuser ring
Top half of the case with the main PCB, with RGB LEDS around the edge.
Top half of the case with the main PCB, with RGB LEDS around the edge.

Metal Chassis with Processor PCB

Inside you will find a circuit board mounted to a cast metal housing with a small ribbon cable leading to the switch PCB.

The PCB is removed using four torx bolts and the removal of a small flat-flex cable. 

With the PCB removed the four silver torx screws can be removed which allows the metal housing to be removed from the top cover. This reveals the switch PCB and speaker.

PCB removed showing speaker connection pads and ribbon cable to the switch PCB
PCB removed showing speaker connection pads and ribbon cable to the switch PCB
The metal housing removed from the top dome revealing the speaker
The metal housing removed from the top dome revealing the speaker

Upper side of the Processor PCB

This new version of the Echo Dot uses different processor to the previous Echo Dot models. A MediaTek 2GHz dual-core ARM CPU with Amazon AZ1 Neural Edge processor, part number MT8512BAAV and a SK Hynix LPDDR4 SDRAM 4G-Bit RAM IC (H9HCNNN4GUML) which are located under a metal shield.

Below the CPU and Ram is a MediaTek Wi-Fi / Bluetooth Controller, part number MT7653BSN which has outputs to two PCB antennas, one on each side of the board.

On the older models of the Echo Dot the metal shields had removable covers but on the new revision 4 these are soldered to the PCB and require a lot of heat to remove them.

Whilst removing the processor and ram shield with the hot air gun, two of the small components on the RF feeds to the antenna blew away from the board due to the hot air and they had to be replaced with small solder bridges to restore the antenna functionality.

Above the metal shield are the power and speaker sockets.

The processor PCB also contains several power supply ICs to provide the different voltages needed for the unit.

There is a single flat flex connector which links the processor PCB with the top switching and microphone PCB.

Top of the main PCB showing WiFi / Bluetooth IC at the bottom and shielding over the CPU and RAM
Top of the main PCB showing WiFi / Bluetooth IC at the bottom and shielding over the CPU and RAM
Top of the PCB with the metal shielding removed showing the main processor and ram
Top of the PCB with the metal shielding removed showing the main processor and ram
CPU and RAM under the metal shield
MT8512BAAV - MediaTek 2GHz dual-core ARM CPU with Amazon AZ1 Neural Edge processor and SK Hynix LPDDR4 SDRAM 4G-Bit RAM under the metal shield
WiFi and Bluetooth chip
MT7653BSN - MediaTek Wifi / Bluetooth Controller
The memory chip under the metal shield
The memory chip under the metal shield, MT29F4G01ABAFDWB-IT - Mircon 4Gb SPI NAND Flash Memory - Marking NQ464
USB debug header pads and audio circuits
USB debug header pads and audio circuits

Lower side of the Processor PCB

On the lower side of the main PCB are 12 RGB LEDs around the edge which are driven by an LP5036 Texas Instruments 36-channel I2C constant current RGB LED driver.

The internal speaker is driven by a TAS5805M Texas Instruments 23-W stereo, 45-W mono, digital input Class-D audio amplifier

The headphone output is driven using a PAM8908 Diodes Incorporated 25mW stereo headphone driver.

Under the metal shield is a MT29F4G01ABAFDWB-IT - Micron 4Gb SPI NAND Flash Memory - Marking NQ464 which contains the operating system.

There is a chip marked MT6398AN which is an unknown MediaTek part but based on the surrounding components it could be a switching PSU.

Bottom of the main PCB showing the metal shielding can over the memory chip
Bottom of the main PCB showing the metal shielding over the memory
Metal shield removed
Metal shield removed showing the Mircon 4Gb SPI NAND Flash Memory

Upper Switch PCB

The small round PCB which is screwed into the top of the case contains four buttons, two LEDs and a light sensor on the upper side with a soft rubber gasket.

The Switch and Microphone PCB in the top of the case
The Switch and Microphone PCB in the top of the case
Switch PCB removed showing mounting brackets and switch locations.
Switch PCB removed showing mounting brackets and switch locations

On the reverse of the circuit board are four microphones and a TLV320ADC5140 Texas Instruments Quad-channel 768-kHz Burr-Brown™ audio analogue to digital converter.   There are several other smaller ICs on the board, but we could not find any information on what they are.

The Echo dot uses the four microphones to locate the direction the voice is coming from and filter out background noise.

Top of the Switch PCB showing the four control switches and holes for the microphones
Top of the Switch PCB showing the four switches and microphone holes
Back of the Switch PCB showing four microphones and a single ADC chip
Back of the Switch PCB showing four microphones and a single ADC chip
Back of the Switch PCB with single ADC chip and other components
Back of the Switch PCB with single ADC chip and other components. The ADC is a TLV320ADC5140 Texas Instruments Quad-channel 768-kHz Burr-Brown™ audio analog-to-digital converter

All internal parts

All the internal parts which make up the echo dot.

Teardown Complete
Amazon Echo Dot Revision 4 Teardown Complete

The video below shows the teardown stages.

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1 Comments


Rick

17 January 2021 at 3:46 am

Is there a digital potentiometer at the audio amp input? Trying to understand why the dot only had 10 discrete volume levels.


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