Corporate FAQ

What is the difference between Shelf Edge LCD Display and Stretched Bar LCD Display?

Shelf Edge LCD Display has a more significant aspect ratio and is mainly used in retail areas, such as shopping malls, supermarkets, convenience stores, pharmacies, etc.

Stretched Bar LCD Display can satisfy all your imagination of LCD products. Through DNR cutting technology, LCD glass can be cut into strips, squares, or even circles, ensuring that it can be used in different environments. In all the places you can think of that need digital display, Stretched Bar LCD Display can exist in a unique form.

1. Observation method:

Observe the main chip, PCB board, power IC, and each slot.
① Observe whether the main chip has obvious burning, scorching, or burning.
② Check whether there is a short circuit in each slot.

2. Touch method:

(Power on for a period of time): Touch each chip, IC, etc. of the motherboard to see if it is overheated or overcooled.
Overheating: ①Internal short circuit, ②High power supply voltage.
Too cold: ①open circuit, ②no power supply, ③working conditions are not met.

3. Resistance method:

ISA: The first 8 D lines have the same R to ground.
In the early stage, the 20 A lines have the same R to the ground (some boards are segmented).
The last 7 lines A are the same to the ground R.
The last 8 D lines have the same R to ground.
They are generally no more than 15Ω between each other, and the difference between IRQ, DRQ and DACK is no more than 25Ω.
PCI:
Thirty-two AD lines have the same R to ground, and it is normal for some motherboards to have one that is tens of Ω smaller than the other 31 to ground.
AGP:
32 AD, 32 AD lines are the same to the ground R

4. Waveform method:

Important test points: RESET, SCLK, OSC, BE0-BE7 (signal that allows data address work) A3 (reflection of the flag of South Bridge work), CS, OE.

5. Locking wave method:

For motherboards below 586, PⅡ and PⅢ are not allowed, otherwise the CPU will be burned).
Connect the A23-VCC on the CPU socket and compare the waveforms of the test points. If the waveforms of the data signals in the same segment are consistent, if there are inconsistencies, use the resistance method to find the fault point. (Prerequisite: The three major conditions of CPU work are met, and there are some waves on the ISA and PCI slots).

6. Digital card method:

(reflect the process of BIOS self-test)
FF, 00 CPU does not work or the working conditions are not met, the motherboard has a serious fault (mainly check the three major conditions of CPU work, BIOS, and main chip).
CI, C6  memory slot (memory bar) memory control part (mainly check memory power supply, north bridge, memory slot, clock failure, etc.).
31 should be displayed. If it is not displayed, check the AD line on the PCI, there may be an open circuit or a short circuit.
C1→05→C1→05 (cycle)
1. Memory slot. 2. CPU power supply. 3. I/O chip. 4. KBC.
U1→05→U1→05 (cycle)

7. Logical reasoning method:

Mainly used to infer TTL, 74 series, the quality of the gate circuit.
NOT gate: inverter OR gate: adder AND gate: multiplier

8. Substitution method:

When the specific component cannot be determined, replace the suspected component with a good one. This method is widely used in practice.

We will provide a warranty ranging from 1 to 3 years in accordance with the laws and regulations of the customer’s location.

At the same time, we will also provide customers with lifetime online support.

1. Check the three major working conditions of the CPU

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Clock
Reset

2. Remove the BIOS and check if the 22-pin chip select signal has jumped

3. Try changing the BIOS and check the line connected to the BIOS

4. Check ISA, PCI data lines, address lines (and AD), interrupts and other control lines (this can directly reflect the North-South bridge problem)

5. Check the ground resistance of AGP, PCI and CPU block to judge whether the north bridge is normal

(1) Power supply CPU core voltage

(1) No voltage

A, FET is broken, open circuit or short circuit
B, filter capacitor short circuit (electrolytic capacitor)
C, voltage IC, no output, no 12V power supply

(2) Low voltage
A, CPU working voltage related circuit has a slight short circuit
B, a field effect tube is broken, the output voltage will also become lower
(3) High voltage
C, the feedback circuit has no effect
D, voltage IC output voltage is low

(2) VID0－4 (+5V voltage)

The voltage IC has no output. The resistor connected to the CPU socket is broken.

(3) VTT 1.5V

(1) No voltage
The power supply FET is broken
VTT1.5V has a short circuit to ground
(2) Voltage level
FET power supply is not normal
FET is broken

(4) Clock

(1) No clock
Open circuit between CPU socket and clock IC
No output from clock IC
The filter capacitor connected to the output is broken (10 picofarads)
(2) The clock IC has no output
Is the power supply normal 3.3V 2.8V 2.5V
All no output or half of no output
Whether the crystal oscillator starts to vibrate 22 picofarads are broken
(3) No output at all
No power supply, check power supply related lines
(4) Half of no output
IC is broken, half of the power supply is checked abnormal

(5) Reset

(1) 1.5V without reset
A, reset voltage is low: Northbridge is broken
B, there is voltage without reset
North Bridge false welding or North Bridge without reset
The line connected to the North Bridge is disconnected
(2) The north bridge has no reset (see whether PCI, AGP, IDE are normal)
Reset: disconnected from the North Bridge
No reset: check the reset generating circuit