Preparation Deng Yi
Contents of this brochure
：
The main story S9 Troubleshooting of various faults in the Operation board
，
how to use the test box for accurate
positioning.
Range
：
Applies to All S9 Production
，
After sale
，
Outside the coordination repair site
One Maintenance Platform Requirements
：
1, Thermostatic soldering Irons
（
350 -400
），
Tip tip for solder chip resistor capacitors and other small patches.
2, hot air cylinder for chip disassembly welding
，
be careful not to heat up for a long time lest PCB Foaming.
3, APW3 Power
（
Output 12V
、
133A Max
），
Used for test measurement of the Operation board.
4. Multimeter
，
Sub-camera
，
S9 Test Jigs
（
Conditional configurable Oscilloscope
）。
5, flux, washing plate water plus anhydrous alcohol
；
Wash plate water is used to clean and repair the residue and appearance of welding.
tin-Planting fixture
，
Tin-sik Steel mesh
，
Solder Paste
；
When replacing a new chip
，
you have to plant tin on the chip.
7, Thermal conductive adhesive black
（
3461
），
Re-glue the heatsink after servicing.
Two Job requirement Items
：
1
、
Maintenance personnel must have some knowledge of electronics
，
More than one year of maintenance experience
，
对
QFN Packaging
welding technology Proficiency.
2
、
After maintenance, the operation board must be tested two times OK
，
before you can pass
！
3
、
Pay attention to the operation method when replacing the chip
，
after replacing any accessory PCB No obvious deformation of the
plate
，
Check the replacement parts and the surrounding there are few open circuit problems. 4
、
Determine the maintenance station
object and the corresponding test software parameters, test fixture.
5
、
Inspection Tools
，
Whether the fixture can work properly
Three, principle and structure
：
●Principle Overview
1. S9 is composed of 21 voltage domains connected in series. There are 3 BM1387 chips in each voltage domain, and there are 63 BM1387 chips in the whole
board.
2. The BM1387 has a built-in buck diode with a step-down diode function that is determined by the chip's designated pin
3. S9 is 21 voltage domains (S5+ is 16 voltage domains, S7 54 chip is 18 voltage domains, S7 45 is 15 voltage domains); S9 clock is 25M single crystal
oscillator, connected in series by The first chip is passed to the last chip.
4. S9 There are independent small heat sinks on the front and back of each chip. The small heat sink on the front side is the SMT patch. The small heat sink on
the back side is fixed on the back of the IC by the thermal adhesive after the initial measurement. Repair and replacement chip test
After the test, you need to evenly apply black thermal adhesive on the IC surface and heat it.
It is important to note that
：
In the maintenance process, in order to reduce the damage of the high temperature of the air gun to the PCB and the chip when replacing the
components of the electric board or the chip, it is necessary to first place the small heat sink near the faulty component and the PCB board.
After the small heat sink on the back is removed, replace it.
The PCB board has test points anyway, during the maintenance of the production, the front test points can be used when the heat sink is not
attached to the front of the PCB; the finished product repair (after-sales maintenance), due to the front and back of the PCB
Covered with heat sinks, it is necessary to locate the fault through the test points of the PCB. The special slender pen can be used to probe the
gap of the heat sink for measurement, but since the SMT small heat sink is connected to the ground of each voltage domain,
When measuring, pay attention to the insulation of the test leads to avoid short circuit caused by the test leads. .
