RBK20 is a pair of sets, is really a pair, two different models, the main and vice are distinguished, the main model is RBR20, used as an extension of the one model is RBS20.
The appearance and hardware of the two units are the same, open the package:
All items in the package.
Although the host and sub models are different but the body and hardware are the same.
The two units are a smaller version of the RBK50, and the top of the body is colored to distinguish the main unit from the secondary unit.
The back of the body is shown below, two full Gigabit network ports, no USB port. The network port logo with yellow is the host.
The power supply specification is 12V/1.5A. After connecting to the network, the standby is 6.2W, which is good for this power supply. It comes with a flat cable, and it is 2 meters long, which is also good. Although always dislike flat network cable, but the length is given enough.
To prove that the two bodies have the same hardware, I weighed the weight of both. The difference is 0.2 grams, which I guess is the weight error of the housing. The left side is the main unit RBR20, the back is the secondary unit RBS20. in this article I only disassemble the RBR20.
Dismantled this one RBR20.
The bottom label is torn off, a row of interface of a circle label is also torn off, see 2 screws, remove to separate the shell.
After the shell is split in half, see the motherboard and the built-in antenna.
Built-in four metal round tube, belong to the omnidirectional antenna, three frequency are 2t2r, but only four antennas, not log yo 。。。。 In fact, the longer one is a dual-band antenna, as long as you see a long and a short antenna, the long one will always be 2.4G antenna, the short one is 5G antenna, the higher the frequency, the shorter the antenna. 60G antenna is smaller.
The longer one is a dual-band antenna, the short one below is a single-band 5G, and is low frequency, because the antenna feed line connector next to the sign “5G L”.
There are 2 filaments, the same as the connection screws of the shell are internal plum screws, dismantled a few mesh parts are. This angle of view, feel good.
After separating the motherboard from the housing.
Main board body side.
The other side of the motherboard with the mesh port.
The motherboard has heatsinks on both sides.
Four screws hold the two heat sinks in place. Disassemble the heatsink.
There are 2 bumps that are attached with screws.
The other side is also structured in such a way that
Two aluminum heat sinks.
First remove the motherboard with the side of the mesh:
There are three pieces of shield, after all removed.
Thermal conductive silicone pad is relatively thin, I took off after broken into this. It’s okay, I have 1mm thermal conductive silicone, replace it with a beautiful.
The chip model with the largest area is the CPU, model number IPQ4019.
IPQ4019 is a quad-core 717Mhz, 4x ARM Cortex A7, Quad-core CPU. it integrates 2.4G and 5G wireless controller, 2x2mimo, 256-QAM, 2.4G rate up to 400Mbps, 5G rate up to 866Mbps; supports MU-MIMO, supports Qualcomm® Wi-Fi SON. 40nm chip process.
IPQ4019 external 2.4G and 5G independent amplifier, the lower left corner of the two long components, silk-screened with the word “5697”, is a dielectric filter (Dielectric filter), 5697 is estimated to be 5G frequency range, its role is: only allow the frequency components in the resonant frequency Near the resonant frequency of electromagnetic waves through, play the role of band-pass filter.
The small black chip on the top, silk-screened with the words “SKY11 85325”, model SKY85325-11, is a 2.4G amplifier chip, integrated with PA and LNA.
SKY85325-11 parameters are as follows.
Integrated high-performance 2.4 GHz PA, LNA with bypass, and
LNA with integrated bypass mode
Transmit gain: 25 dB
Receive gain: 16 dB
Output power: +18.0 dBm, MCS9, HT40
Output power: +19 dBm, MCS7
Small QFN (16-pin, 2.5 mm 2.5 mm) package
At 256-QAM and 40Mhz bandwidth, the amplifier power is +18dBm = 64mW, which is a low power amplifier.
In addition, at the bottom of the silkscreen with “SKY 729”, the model number is SKY85729-11, which is a 5G amplifier chip with integrated PA and LNA.
The parameters of SKY85729-11 are as follows.
Integrated 802.11ax , 5 GHz PA, LNA with bypass, and T/R
Fully-matched input and output
Integrated logarithmic power detector and directional coupler
Transmit gain: 32 dB
Receive gain: 13 dB
MCS11, +18 dBm, -43 dB EVM
MCS9, +22.5 dBm, -35 dB EVM
MCS7, +24 dBm, -30 dB EVM
Small QFN (16-pin, 3 x 3 mm) package
Look at MCS9 that line on the line, amplify the high power + 22.5dBm = 178mW, medium power.
The other side of the CPU, next to the network transformer with the switch chip, there is a metal sheet blocking, all right, I used diagonal pliers to break it open.
The IPQ8072 is a Gigabit switch chip, supporting 10/100/1000Mbps. it has a CSR8811 Bluetooth chip underneath, but the Bluetooth antenna is not connected.
The Bluetooth antenna is the white rectangular ceramic antenna next to the jack in the picture below (in the lower right corner of the picture below), the Bluetooth antenna interface is actually an RF test seat, the test thimble inserted into this seat will be disconnected from the antenna, so that the thimble is directly connected to the chip.
This side is finished removing. Turn to the other side. This side is IQ4019 + QCA8072 + CSR8811, amplifier chip is SKY85325-11 and SKY85729-11.
The other side of the motherboard after removing the shield.
First look at the memory and flash memory, in the large shield is the memory chip, the model is South Asia’s NT5CC256M16EP-EK, DDR3 memory, capacity 512MB. flash memory model is W29N02GVSIAF, capacity 256MB.
The top picture leans on the smaller shield is another 5G circuit. Zoom in to see, 5G wireless chip model is qCA9886, also 2x2mimo, the highest rate of 866Mbps. 2 silk-screened with 5235 on the left is a dielectric filter, the front also, has been introduced. Red cabinet more need to have two tiny chips, look at the circuit alignment is the RF transceiver, transmitter switch. There is no external independent power amplifier chip (PA and LNA).
Closeup of one of the chips in the red box above, the left is connected to the antenna all the way, the right is divided into two ways to connect the wireless chip, so it must be a T / R switch, not a FEM chip.
RBK20 is a tri-band, there are two 5G, respectively, IPQ4019 and QCA9886 is responsible for the control, which one is used to do the wireless backhaul? After I reboot, the phone connected to its 5G are 36 channels, according to the frequency on the media filter used, I guess the QCA9886 chip, QCA9886 is responsible for signal coverage, so that wireless devices connected to use, and IPQ4019 built-in 5G is dedicated to wireless backhaul.
Personal guesses are as follows.
The disassembly is now complete.
Can not separate 2.4G and 5G, I have always felt that this choice should be given to the user to choose.
After several attempts to update the firmware, I had no choice but to go to the official website of Netgear and download the firmware of RBR20 and RBS20, and then update it manually behind the desk.
Upgrade to the latest firmware V126.96.36.199.
Dual-band in one, why don’t I like it? The roaming sometimes connect to 2.4G after it is difficult to go back to 5G, from the main to the vice when the switch to the vice 2.4G, and then go back to the main also connected to the vice 2.4G will not switch to the main 5G. unless you switch WIFI, or rest screen after waiting a while to open the screen this is possible to switch to 5G, because the rest screen may be WIFI will automatically turn off. Huawei mate20 phone is like this, as follows.
Seamless roaming is no problem, can automatically switch, when switching play king will not drop reconnect, just when the switch into 2.4G, and then go back to the other node next to the 2.4G signal weakness will not automatically connect to 5G, then play king will not be cool, will increase the delay. Do not mind only the dual-band in one and did not pull the network cable can be considered.