Why is it so light? Disassemble a look!

At the end of 2016, after more than two years of music as the box, finally with its new series of products - LeTV box U4 proudly return, flat black box design, 100mm100mm10.8mm body size, attracted the attention of the public. It's hard to say that it's not the thinnest box on the market so far. Whether it's the material selection process or the structural design, it provides a new reference for the popular market. However, behind the pride, why is it so light? We can not help but want to see a thorough!

Next, let's take a look at the inside story of LeTV's U4 lightweight design.
The first impression of LeTV's U4 box should be the use of a screw-free design, including my own; it was only discovered when disassembled, but it used a concealed screw design, the appearance of the structure through The three screws in the bottom soft rubber anti-slip mat are fixed. Therefore, the first step in dismantling is to tear off the bottom soft rubber feet. It is best to wear plastic gloves. [I tear it a bit ugly, do not care]



Unscrew the 3 screws securing the box.




Use the paddle to gently separate the UF body buckle from the LeTV box.



After dismantling, we found that LeTV's U4 has a very high space utilization rate, almost no visible space, and the size of the entire PCB is much smaller than similar ones. Fully black PCB is fixed in the upper panel of the box with 3 screws. Unlike many mainstream boxes, the LeTV U4 is not equipped with a shield, even if it is a front control area.

Triangular structure of the fixing screws.


Gently push apart the metal contacts of the two WiFi antennas.



Unscrew the 3 screws that secure the PCB. In fact, whether it is the outer structure or the internal structure, LeTV's U4 screw is tightly tightened, which also ensures its good solid performance, even if it is light and thin, it can give people an excellent sense of solidity.

After removing the PCB, you can see that a large area of ​​the counterweight is fixed on the upper level board (I have taken it for granted that it was not equipped with heavy metals before dismantling) and the dual WiFi antenna.

It is worth mentioning that, because LeTV U4 is not equipped with a network port, so in order to get a stronger signal reception and transmission capabilities, LeTV box U4 is equipped with 2.4G/5G dual-band WiFi, and integrated dual antenna design, WiFi antenna by the American Airgain Company offers. Airgain is a professional R&D intelligent antenna manufacturer that has been established for more than ten years; the company formerly used the US military and the universe industry to provide expensive radar systems and multi-antenna smart antennas for communication equipment, LeTV's U4 combined Airgain dual antenna, not only The gain of the antenna is increased, the reliability of the device is effectively improved, and the ability to send and receive signals is further enhanced, and synchronous multipath interference is reduced.
The metal counterweight has a large paved area. On the one hand, a certain amount of component sensation is ensured by increasing the area and reducing the thickness. On the other hand, the large-area metal counterweights greatly ease the heat dissipation of the box body, and the heat conduction is more efficient. The control area is also equipped with a thermal film sticker.

This should be the light guide module that is connected to the LED indicator on the PCB and used to conduct the light. To ensure that the entire light transmission will not diverge, uniform concentration of the light guide head, the light is more uniform.





The components on the main board are structured and delicate; all chip technologies, all-chip capacitors, and no-hand-welded parts ensure a more stable quality and a longer lifespan.





In terms of hardware interfaces, LeTV only has a power interface, USB2.0 interface, HDMI2.0 interface, although not much, but it is still enough; the lack of network port can also provide a stable and strong signal through high-gain dual-antenna WiFi design transmission.

Back SEC RAM pellets.

In terms of memory, LeTV Box U4 integrates multiple RAM particles, which is provided by Samsung SEC, model K4B4G1646E-BCMA DDR3, single-chip 512MB, and two-sided four-chip composed of 2G.

Here is WiFi/BT4.1 module, AP6356S, based on Broadcom Broadcom BCM4356 chip production.

Leshi box U4 uses SAMSUNG KLM8G1GEND-B031 particles, 8G eMMc5.0 standard.

Other ICs on the PCB, near the power interface, are SMD Schottky diodes that are used for instantaneous rectification of the circuit.

Next to the master is a JY1117, 3.3V power regulator IC.



The main control part, LeTV U4 uses the S905 CPU from Jingchen Amlogic, a 4-core 64-bit Cortex A53 architecture with a clock speed of up to 2.0GHz, a Mali-450 5-core GPU, and two SEC RAM particles next to it.

If you've seen my former companions of LeTV, Xiaomi, and Tmall's magic box, you should know that the LeTV box U4 and the millet box 3S maintain a high degree of similarity in the size of the box, and the millet box's 3S size is 101mm*. 101mm*19.5mm, LeTV's U4 size is 100mm*100mm*10.8mm. However, the difference in the internal PCB size between the two is still relatively large, which is part of the reason that affects LeTV's U4 light and thin design.
to sum up

In fact, before we took down the machine, we had already envisioned a certain design direction for LeTV U4, including dismantling, and it was almost as much as I thought.
LeTV U4 10.8mm body thickness is not groundless, almost zero remaining internal space utilization, each structural design is very considerate, highly integrated PCB, re-examine the weight and interface configuration. While realizing the basic function placement, the thinness of the box body is maximized. Some people may consider the problem of low space for high-integrity cassettes, slow release of thermal cycling, and reduced thermal performance. In fact, including thermal film, a larger area of ​​weight, etc., all mitigate this problem to a certain extent. Although its temperature control performance can be regarded as the best, it is based on our trial experience. Its performance is still in an acceptable range.
If the thin and light structure will lead the 2017 smart TV box design direction, then the design considerations are still very important. In addition to temperature control performance issues, including the design or stability of the PCB is critical. I also said in the evaluation box of LeTV U4 that the stability of LeTV U4 is very good. While reducing the weight of the counterweight, LeTV also enhances the fixing strength by laying a large area of ​​soft rubber non-slip pads on the bottom surface. Whether it is on the glass surface or on the wooden board, it has a strong viscosity, and it can even be said that it performs better than many other category boxes.
Finally make a concise summary of LeTV U4:
1. Concealed screw + snap-fit ​​design, completeness and structural strength is stronger.
2,100mm*100mm*10.8mm, only 10.8mm thickness of the fuselage, great visual impact.
3, box body material, process solid and fine, high quality.
4. Highly-integrated black PCB design. The components on the motherboard are arranged in a fine and detailed manner. All-mounting processes, no manual welding, and quality are more stable; they are not equipped with a shielding cover.
5, from Samsung's storage portfolio, EMMC5.0, compared to previous generations to increase the transmission rate.
6, Jing Chen S905 64-bit A53 architecture processor, 2GHz frequency, parameter information is not strong, but the actual control experience is good.
7. Dual-band dual-antenna WIFI design. Antennas from American Airgain have strong penetration, higher coverage and signal stability, and can perfectly replace the lack of network ports.
Smart TV/box information can focus on smart TV information network sofa butler (http://), China's influential TV box and smart TV website, providing information, communication, TV boxes, smart TVs, smart TV software, etc. Answering questions.

1800W Three Phase AC Source System

Product Introduction:

APM 3 Phase Ac source SPS300VAC1800W is capable of delivering 1800VA of output power.Very convenient to operate from the front panel keyboard or remote interface. This Programmable AC Power Supply System is useful for testing designs over a wide range of input voltages at 47 Hz and 63 Hz. theouput frequency range from 15~1000 Hz. Magnetic devices such as inductors and transformers can also be tested over a range of voltage and frequency using AC Power Source.

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This AC power supply series is applicable to multiple sectors such as electric, lighting and aviation sectors and it could be applied to enterprise's production test as well.


Product Features:

● Large touch color screen, possess complete functions and easy to operate

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● Output frequency 15~1000Hz, capable of setting output slope of voltage and frequency

● High output crest factor could satisfy surge tests requirements

● Multiple current measuring level selection. Increase measurement accuracy

● Standard USB data interface, support CSV file waveform import

● OCP/OVP/OPP/OTP/ Short circuit protection

● Built-in power meter, which is capable of measuring 15 electrical parameters per phase, including voltage, current, power, etc

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● Capable of setting voltage and current output restriction, support for constant current output mode



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Adjustable Phase Angle/Slope is applicable to verification test of ON/OFF inrush current testing. This function is applicable to start inductive or capacitive load with large capacity to avoid high current when instantaneously start the device.

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The surge current could reach 5-6 times of the rated current, especially suitable for inrush current testing.
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Capable of simulating power line disturbance simulation test.


Advanced Functions:

1.Built-in IEC Standard Test
Built-in IEC standard test could be recalled directly.

2.3-Phase Operation and Parallel Mode

Support 3-phase operation, 3 units in parallel

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