Posts Tagged ‘CLK’

Led Electronic Display Repair Guide

December 13, 2015

Judge issues must be handled after hsien Chu, clear, severe, small problems. Short circuit LED fluorescent lighting should be the highest priority.
1, resistance detection method, adjust the multimeter to resistance, detect a normal circuit board of a point of resistance, then testing another piece of the same circuit board with a points test and normal resistance values are different, different if you determine the scope of the problem.

2 voltage detector, multimeter voltage regulation, detecting suspect circuit voltage of a point, are similar to the normal, or determine the scope of the problem.

3, short circuit LED Flood Light Supplier detection, adjust the multimeter to the short block (some diodes voltage drop or resistance stalls, usually with alarm function), checks for short circuits happen, after finding the short circuit should give priority to, so that it does not burn out other devices. The method you must do so in the case of power off circuit, preventing damage to the table.

Detection method 4, pressure drop, adjust the multimeter to diode voltage drop test document, because all of the IC is made of numerous basic components, but small, so when it comes on a PIN when there is current through, there is a flexible led strip lighting voltage drop on the PIN. General of the same model similar to the pressure drop on the same IC pins, based on pressure drop in PIN value comparison, operation must be power off circuit. The method has some limitations, such as the detected devices are high impedance, not detected. Four processing steps, panels-frequently asked questions Board failure:

A. Panel is not lit

1, check the power supply and the power supply is connected.

2, check whether the test card to identify interfaces, test card red light flashing is not recognized, check whether the lamp power with test cards, or the lamp panel connector interface signal and the short-circuit caused no recognition. (Smart test card)

3, detect 74HC245 deficiency-free welding short circuit, on 245 (EN) signal input or output pin is a virtual welding short circuit to the other lines. Note: the main power and enable (EN) signal.

B. helical scan, regularity of interlacing is not lit display overlapping

A, b, c, d, 1, check whether the signal input to the 245 disconnection or Xu Han and short circuit.

2, testing corresponds to 245 outputs a, b, c, d or Xu Han, short circuit between 138 and circuit breakers.

Detection of 3, a, b, c, d between the signal short circuit or a signal and the short-circuit. Note: the main test ABCD signaling.

C. iseedeadpeople with line or lines are not lit

138 per cent between 1, detection or virtual welding line circuit breakers, short circuit.

D. scan, two or more rows (typically are multiples of 2, law) at the light

1, a, b, c, d, the signal is detected between the short circuit.

2, detect whether 4,953 output and output short circuit.

E. iseedeadpeople with single-point or multi-point (irregular) is not lit

1, find the module corresponds to the measurement and control foot line short circuit.

2, replace the module, or a single lamp.

F. iseedeadpeople has one or more columns is not lit

1, found on the module controlling the PIN, measure and driver IC (74HC595/TB62726) output port connection.

G. single point or highlight a single column, or entire row highlighted, and is not subject to control

1, check whether the column is short circuit and power supply.

2, test the line with power-cathode short-circuit.

3, replace the drive IC.

H. display confusion, but the output signal of a Board under the normal

245 corresponds STB latched outputs 1, detection and driver IC latch-side connections or signal short circuit to the other lines.

I. display confusion does not output correctly

1, detection of clock signal CLK latch STB is shorted.

2, measuring 245 clock CLK input/output.

3, tests whether the clock signal short circuit to the other lines.

Note: the main clock and latch signal is detected.

J. display the missing colors

245 1, detection of the color data of the port has input and output.

2, test whether the data of the color signal short circuit to the other lines.

3, test the color of cascade data between the driving IC is short circuit, virtual circuit breakers or welding. Note: the available voltage detection method is easier to find the problem, test voltage is different from normal data, determine the fault zone.

K. output problem

1, test the output interface to the signal output of the IC line connection or short circuit.

2, the output latch of the clock signal is detected correctly.

3, testing the last drive IC between concatenated output data and the output interface data port connection or short circuit.

4, the output signal is a short circuit or a short circuit to ground.

5, check the output of the cable is good.