Schematic diagrams of tablets. How to bring an unnamed Chinese tablet back to life. External devices connected to the tablet
It was decided to disassemble a very familiar tablet from an online auction () to look at the hardware. These kinds of tablets are very easy to disassemble, you don’t need any tools, your own nails will suffice. The two main parts of the case are joined with latches; more expensive models with a metal back cover use screws. After undocking the two main parts, a beautiful view opens up to the inside of the Chinese tablet for $50.
Despite the fairly high performance of the processor, it is without cooling, there is not even a primitive heat sink, I generally keep quiet about the Peltier element, which is actively used by many manufacturers. Oddly enough, the processor works fine, although it gets so hot that you can boil water on it.
The battery is lithium-ion with a capacity of 1800 mA/h according to the passport, in reality it is as much as 2000 mA/h.
An extra 200mA cannot extend the battery life of the tablet by 5-10 minutes, which is quite a lot! The battery itself has a charge controller that does not allow the battery to be recharged and discharged below the permissible limit, so even a completely discharged battery is charged when charging is connected, but in some models this controller is missing, it is for this reason that a completely discharged tablet will not charge, and will need to be disassembled to charge case and charge the battery separately.
Camera - 0.3 MP passport, 1.3 in real life. During video calls, this difference will not be noticeable, but the extra megapixel is very useful when you don’t have a device at hand, but you need to take a couple of photos for memory.
Nowadays you won’t surprise anyone with a computer, much less a tablet. Surely our descendants will believe that tablet PCs appeared before laptops and netbooks. And this is not surprising, because over their modest history, Tablet PCs have gained enormous popularity.
For everyone interested, I suggest you familiarize yourself with the electronic content of a tablet computer.
The Ritmix RMD-825 tablet ended up in my hands. Yes, the model is budget, cheap, but the composition of tablets, as a rule, differs only in the power of the “component”; there is no fundamental difference in the device.
What's inside the tablet?
The Ritmix RMD-825 tablet is easy to open; the two parts of the case are connected with latches. I opened it with a special opener, which is often used when repairing cell phones. Under the cover I found this.
The printed circuit board requires separate consideration.
CPU.
A single-core processor is installed in the center of the printed circuit board - ALLWINNER TECH A13(1GHz). In the photo on the left, an 8-pin chip in an SO8 package is PCF8563T(8563T) – real time clock ( RTC) with a built-in calendar. Nearby is a chip ( CF227) in the form of a “cigar” is a quartz resonator.
Also not far from the processor you can find a 24 MHz master oscillator chip. Such a small detail, but very important.
ROM.
NAND FLASH memory is used as ROM MT29F32G08CBACA(29F32G08CBACA) on 32Gb (32 gig bit) in a 48-pin TSOP package. Nearby on the board there is a seat for another identical chip - apparently for other modifications of the tablet. The chip manufacturer is Micron.
Similar chips are used in solid-state drives (SSD drives) and USB flash drives.
RAM.
The “RAM” of a tablet is two chips H5TQ2G83CFR DDR3 SDRAM memory 2Gb (2 gigabytes) bit) each. Datasheets for memory chips always indicate memory in bits, not bytes! And to be even more precise, there are 2147483648 bits in this chip. A little more than 2 billion bits. The H5TQ2G83CFR case is BGA, that is, the microcircuits are soldered to the board via solder balls.
Wi-Fi module.
Wi-Fi is provided by a USB wireless communication module based on a Realtek chip RTL8188CUS.
It is connected to the circuit via 6 contacts. 2 of them are the common wire (GND). Next, plus +3.3V power supply and two contacts - USB interface ( USB_DP And USB_DN). An antenna is connected to the RF pin, which looks like a strangely shaped copper plate.
Power circuits.
The power controller is responsible for power supply - microcircuit AXP209. In its harness you can find many inductors and key transistors. It happens that this microcircuit fails.
Very unpleasant breakdowns are sometimes associated with the power controller. So, if it malfunctions, the tablet may not charge the built-in battery, although the charge indication may be displayed on the tablet display. The tablet itself only works when the charger is connected.
This malfunction causes the built-in lithium battery to discharge to a minimum and is turned off by the built-in charge/discharge controller.
As a rule, in this case the tablet is sent to a shelf or desk drawer, where it lies for several months. During this time, the battery is even more discharged and goes into the stage of “clinical death”. Even if it is possible to restore such a battery, its capacity is noticeably reduced, and sometimes after charging it simply swells.
Touchscreen control.
FT5306DE4– capacitive touch panel controller. This controller is used to work with touch panels ranging in size from 4.3” to 7”. The FT5306DE4 communicates with the main processor via the I 2 C or SPI interface.
Like any tablet, the RMD-825 has elements such as a vibration motor (glued to the matrix with glue), a miniature speaker, and a microphone. The board also has a slot for SD cards, a connector for connecting a USB cable, a headphone output, and a power connector. I don’t think it’s worth saying that elements such as connectors, buttons and connectors most often fail.
And finally, let’s see how tablets are made in Chinese factories. It’s surprising how much manual labor there is in this process - I thought that everything had been churned out by robots for a long time :)
You will need
- Android tablet;
- microSD memory card with a capacity of at least 512 MB;
- computer with internet connection.
1 Disassembling the case unnamed Chinese tablet
Typically, this kind of malfunction can be solved in one way - by replacing the tablet software, or flashing. And here it would seem that everything is simple, but we know little about the tablet. That's why it is nameless, because it is impossible to find any information by its name. Therefore, the first step is to determine what processor does this device run on?. To do this you will have to climb inside the tablet.
The designs of tablets can be very different, so here we can limit ourselves to only general recommendations for disassembly.
- Look carefully around the perimeter, along the side edges of the tablet for screws. If there are any, unscrew them.
- If there are any plastic linings or inserts, try to separate them by picking them up with something sharp, but not hard (a plastic knife, for example).
- Try picking up the back cover and walking around the perimeter, separating it from the front. It is convenient to do this with an unnecessary plastic card - it does not scratch the case and is at the same time hard enough to open it.
2 Determination of technical features nameless tablet
When the tablet case is opened, determine the processor model. Most often, the processor is the largest chip on the motherboard of a tablet computer. For example, in this photo the processor model WM8850(position 1). This is a fairly common inexpensive chip in Chinese tablets.
You may also need to know the touchscreen controller model because... sometimes after installation it may turn out that the tablet boots up and works, but the touchscreen does not. In the photo the controller (position 2) is called EKTF2127. This is also a fairly common chip. Typically, the touchscreen controller is located not far from the cable that connects the touchscreen to the motherboard.
Also look at large inscriptions on the motherboard, not related to any specific element (position 3). Perhaps this will be the board version, its number, or even the name of the manufacturer. This information will make it easier for you to find the firmware you need.
An important parameter is also screen size and resolution, if you remember.
In general, you need to collect as many characteristic features of your “anonymous” tablet as possible. This set of features is like fingerprints, by which one can establish his “personality”.
3 Finding suitable firmware for an unnamed Chinese tablet
Android tablets usually support several flashing options:
- via WiFi network,
- from a computer via a USB cable,
- from a bootable microSD card.
The most suitable option in our case is update using bootable microSD card. To do this, you need to find the appropriate firmware, load it onto the memory card, reboot the tablet and wait until the operating system is installed. The functionality or malfunction of the tablet depends on how successfully you can find the firmware.
Type a query in the search engine with all the data that you found for your tablet. For example, for the case under consideration, the request could be like this: w70 WM8850 firmware And the very first links in the Yandex results lead us to the desired result.
Read these sites, look for what is most suitable for your Chinese tablet. Typically, such thematic forums provide detailed sequential descriptions of the process of updating the software of various devices and provide multiple links to firmware, both official (factory) and unofficial (developed by enthusiasts).
note
When loading inappropriate firmware onto a tablet, there is a risk of turning the tablet into an inoperable, useless “brick.” Reflash your tablet at your own risk or contact a service center.
Today we are using tablet computers more and more. The main quality of such a device can confidently be called its mobility - the user is not tied to his workplace and can stay in touch as long as necessary, and at the same time constantly be aware of all important events. Today, everyone uses a tablet to their own taste, for some it’s just a stylish accessory, some like to read a lot, some need it for meetings and presentations, and some just listen to music or watch movies. The compactness and lightness of this device allows it to be used even in the school curriculum. More and more parents are replacing regular heavy textbooks with compact tablets with electronic versions of books. Of course, many are curious about what is inside this device. This is exactly what we want to tell you about in this article.
The most important components of a tablet computer are:
- motherboard
- of course, the case, which, as a rule, consists of two parts - the back panel and the front part, on which the touch screen is attached.
Touch screen is an information input device that responds to touch and allows the user to “communicate” with his device in a language he understands. The advent of touch screens in mobile devices made it possible to remove the conventional mechanical keyboard and make a huge display, as well as simplify surfing the Internet and greatly expand the multimedia capabilities of the device.
But there are also inconveniences. The touch screen consists of the touch panel itself, a cable for connecting to the system board and protective glass, which makes the sensor a very fragile spare part, which is why touch screens often need to be repaired or replaced. To ensure the strength of the touch screen, our store offers additional tempered protective glass, which will take the full impact if the device falls. The additional protective glass will most likely break, but in any case, it is easier and cheaper to replace than a touch screen, and you won’t have to disassemble the tablet. In case your touch screen is cracked, we offer touch screens for most tablets of well-known brands, such as Acer, Apple, Asus, Fly, Lenovo, Samsung, Sony, as well as a huge selection of touch screens for Chinese-made tablets China-Tablet PC, and other models.
If you have any questions about replacing the touch screen, we recommend reading our article
Typically, the touch screen is attached to the tablet in two ways - either with double-sided tape to a plastic frame, or with ultraviolet glue directly to the display. We offer a wide selection of high-quality adhesives, selected specifically for gluing touch screens, as well as adhesives that harden under ultraviolet radiation. By the way, we made a whole video about adhesives, which you can watch here:
Today it is simply impossible to imagine a modern gadget without cameras. Tablet manufacturers usually use 2 cameras. The main camera is designed for high-quality video shooting, and, as a rule, has high resolution and all sorts of elements for image stabilization. The front (front) camera looks directly at you, and is mainly used for video communication; it has a low resolution for comfortable signal transmission over mobile networks. The front camera, and sometimes the main one, is attached to a plastic frame, which partially serves as the front panel of the tablet body.
If the touch screen is an input device, then display - output device. It displays information in graphical form in a format that is understandable to humans. The higher the display resolution, the clearer the picture will be.
The most common display failure will always remain mechanical damage, in other words, a broken display. If you have such a problem, we are always happy to help you. Our store offers a large selection of displays for tablets in different configurations, separate displays, displays complete with touch screens, and also complete with a frame.
The “skeleton” to which all components of any mobile device are connected is motherboard. This is a complex multilayer dielectric plate, on the surface and in the inner layers of which conductive circuits of an electrical circuit are located. The motherboard contains many electronic components, connectors for mechanical connections to other parts of the device, and a user interface by soldering.
- Coaxial cable, with such cables, antennas are connected to the system board using soldering or a special connector.
- A small speaker (bell) is designed to play melodies, speech, movie soundtracks, game soundtracks and any other sounds that your device makes.
- Charging connector. Some manufacturers make it separately so as not to occupy the USB port when it is necessary to work with the device while charging, and in some cases charging is carried out only through the micro-USB connector (indicated as number 5 in the figure)
- The mini HDMI connector is designed to output video signals to other devices, this could be a TV, monitor or, for example, a projector.
- micro-USB, a connector with which you can connect an external keyboard, mouse, flash drive to the tablet, is also used when exchanging information with a PC, and in some cases for recharging.
- Microphone. This device is designed to convert mechanical vibrations (sounds) into electrical signals so that your speech can be recorded or transmitted over a network.
- Slot for a multimedia card. Used to increase the amount of memory in which your data is stored. The connector for a SIM card also looks similar; in the example we analyzed, this module is missing.
- Connector for connecting an external headset. Putting a tablet to your ear is not at all convenient, so for conversation use external headphones with a microphone.
On the other side of the motherboard, various electrical elements, microcircuits and connectors are soldered for connecting a display, touch screen and cameras. A microcircuit, in other words, an integrated circuit or chip (microchip) is a miniature electronic circuit made on a semiconductor substrate or film, most often placed in a non-separable housing.
- Bluetooth, WiFi and FM radio control module
- ROM is a read-only memory device, a place where information recorded by the user, photos, videos, documents, programs is stored.
- The power management chip, in other words the power controller, is responsible for charging the tablet, as well as powering other internal components.
- CPU - central processing unit (CPU, literally - central processing unit), or simply a processor, as we used to call it. This is essentially the main brain of our device, which processes data by performing arithmetic and logical operations and controls all devices. The main characteristics of the processor are clock purity and performance. Energy consumption is also an important factor.
- RAM is a random access memory device (Random Access Memory, RAM, random access memory), simply put, “RAM”. This type of memory is designed to store variable information; it allows the contents to change as the microprocessor performs its operations. It is where all currently running programs and their data are stored.
- Touch screen controller. This is a microcircuit that, using an algorithm written into it, calculates the coordinates of the touch point and converts them into a digital code understandable to the microprocessor. In some embodiments, the microcontroller can be placed directly on the touch screen cable.
- Main camera connector
- Front camera connector
- Display connector
- Touch screen connector
Tablets that support mobile communications also have a power amplifier, and in more expensive versions the tablets are equipped with video processors.
The mobility of this entire complex device is ensured, of course, accumulator battery.
Tablets have become a part of everyday life. The first such gadget appeared in 1989. And it was released by Samsung. It had a black and white screen and the tablet allowed you to do very few things. Its price was astronomical - as much as $3,000. This cost scared off potential buyers.
Therefore, the owners of such devices were those who really needed such mobile devices. Most often, the buyers were entrepreneurs, company managers, and accountants at the highest level. But today it is a completely affordable device for the average person.
Components of a modern tablet
The tablet device includes a display, a touch screen, a motherboard and a battery.
The display itself is a means for displaying visual information. The smallest diagonal size is 7 inches. A gadget with such dimensions easily fits in your hand. It's great for reading books. And if you have a good battery, it holds a charge for a long time. Larger diagonals start from 8.9 to 10 inches. The large screen allows you to watch various videos and movies without looking closely. The touch screen is used to enter data and control the tablet. It is divided into the following types: resistor, capacitive, matrix, projection-capacitive, surface acoustic wave screen and infrared ray grid screen. The main types of sensors used in tablet circuits are the first three types due to their practicality and durability. The last two are extremely rarely used due to the high cost and complexity of management.
The motherboard is an important element in the tablet circuit. This electronic “stuffing” includes: memory, processor, video accelerator and components connecting them. All these components are installed on the tablet's motherboard. This is a very “capricious” module that can fail under the influence of moisture, temperature, voltage drop and other factors.
Charging the tablet
The last part of the tablet's circuitry was the battery. They are divided into two types: lithium-ion and nickel-cadmium.
In most cases, Li-ion batteries are used to power the tablet. They have an advantage over NiCd batteries in size (with the same capacity), are characterized by low self-discharge and low operating costs over their entire service life. However, they are inferior to them in terms of discharge speed at subzero temperatures and the presence of a protection circuit built into the gadget.
External devices connected to the tablet
The first thing that connects to a mobile device is adapters. They provide power to the tablet and recharge the batteries. There is a special slot for this. Other things that can be connected to the device are monitors and LCD TVs. Some of the tablets even come with HDMI ports, allowing you to enjoy high-quality video viewing. If your gadget does not have HDMI connectivity, you can try doing it via Bluetooth or Wi-Fi. For example, Samsung TVs have a Smart TV function that allows such a connection. Connecting a mouse and keyboard is difficult. The fact is that not all tablets support OTG mode. It is this function that allows the gadget to recognize these devices. As a rule, information about the availability of such an opportunity is available in the passport of the mobile device. There are no special problems with connecting a flash drive. All you have to do is insert it into the USB connector and use it without worry. It is also easy to connect an audio headset, speaker system and portable speakers to a special socket on the tablet. It is also possible to connect wireless headphones. To do this, you only need an additional modem. The development of the gaming industry required the use of joysticks in tablets. But you need to know that not all games support this device. Wireless Internet is connected using Wi-Fi. To do this, you need a modem connected to a USB port.
Best tablet model
According to Yandex.Market, the most popular model in 2017 was the Microsoft Surface Pro. This gadget has a Core i7 processor on board, which is very impressive. In the basic version, it has 256 GB of internal memory. But if desired, you can install an additional slot for a memory card. The 12.3-inch diagonal screen shows a resolution of 2736 x 1824. There are two cameras: 8 MP main and 5 MP front. The manufacturer guarantees 13.5 hours of continuous video viewing without recharging the battery. There is “support” for a keyboard, which makes the device closer to a netbook. The only drawback is the price. It starts from 103,000 rubles.
Conclusion
Despite the fact that the designs of tablets from different manufacturers differ from each other, they perform the same functions: maintaining cellular communications and acting as a multimedia entertainment center, as well as surfing the Internet. We can definitely say that the tablet occupies a middle step between a phone and a laptop. At the same time, due to the increase in the “power” of the electronic “stuffing”, he constantly strives for a laptop.
