Monotonicity of optical modules can also lead to various problems. Mshine Optics lists some examples of optical modules, analyzes the causes and solutions corresponding to different phenomena.
Method/Steps:
1. Phenomenon description: Loss digital resistance failure occurs in monotonous modules
Cause analysis: The module’s LOS A and LOS D cannot be adjusted.
Repair method:
a. Manually testing LOS values using testing software
b. Check if the ROSA optical port is aligned with the optical port, and reinstall the module for testing
c. Check if there is tin connection during the repair welding process of capacitors C14 and C15 at the high-speed signal of the receiving end
d. Check if the ROSA RSSI pin is broken
e. PCBA pads are poorly soldered or connected between solder joints on the pads; Re weld.
2. Phenomenon description: Module has no eye diagram output.
Cause analysis: The eye graph instrument cannot receive light signals, and the module has no light output. Repair method:
Repair method:
a. Confirm whether the test fiber is connected incorrectly during the testing process;
b. Automatic template setting of the eye graph instrument to avoid crashes during long-term testing;
c. Test whether there is light output at the TX end using optical power
d. Check the bias circuit and modulation circuit provided by the module for any false soldering or open circuits (focus on checking the components circled in red)
e. Measure if the TOSA FPC is broken
f. Replace TOSA
3. Phenomenon description: Read Dut temperature failure occurs during module monotonic process
Cause analysis: The module is unable to monitor temperature or there is an error in temperature
Repair method:
Check if the temperature serial port or temperature line is connected properly.
4. Phenomenon description: A0/A2 check failure during module monotonic process.
Cause analysis: The main reason is the omission of burning during the assembly process.
Repair method:
a. Re burning during assembly.
b. During testing, the module was not properly plugged in due to I2C communication errors; Pay attention to operation.
c. The long-term wear and tear of the testing board mold mouth has caused unstable I2C communication; Regular replacement of the mold mouth.
5. Phenomenon description: Moyu module test RX-ADC failed
Cause analysis: The sampling value at the module receiving end is not within the range
Repair method:
a. There is no conduction between the FPC RSSI pins; Replace ROSA
b. ROSA monitoring leads to a small ADC value; Confirm the cleanliness of ROSA end face and fiber end face;
c. ROSA monitors ADC values to be zero; ROSA’s RISS pin is short circuited or poorly soldered to GND; Re weld.
6. Phenomenon description: Module testing LOP out of spec
Cause analysis: The module’s adjustment of optical power is not within the range
Repair method:
a. TOSA end face dirty or fiber end face dirty; Confirm the cleanliness of the end face by removing the sleeping needle.
b. EMI tape wrinkling during TOSA assembly leads to poor coupling between TOSA and optical fibers during assembly; Replace EMI tape and reassemble.
c. TOSA itself has a low SE, and SPEC beyond the testplan cannot be initially adjusted; Replace TOSA.
7. Phenomenon description: Module test SE is too low
Cause analysis: The slope of the module optical power adjustment equipment prompt is too small
Repair method:
a. TOSA end face dirty or fiber end face dirty; Confirm the cleanliness of the end face.
b. EMI tape wrinkling during TOSA assembly leads to poor coupling between TOSA and optical fibers during assembly; Replace EMI tape and reassemble.
c. TOSA itself has a low SE, and SPEC beyond the testplan cannot be initially adjusted; Replace TOSA.
