Fault Analysis and Handling of Optical Modules

The daily use of optical modules may encounter various problems, and I do not know how to solve them. The following will introduce the causes of various problems and how to deal with them.

Optical module

method/step

1. During the test, the value of the module I BiasADC is 0, and the TXLOP-ADC and RX-ADC cannot be tested. Reason analysis: Due to the PCBA layout design problem of the module, the filter capacitors of L1 and the reference power supply in the power supply circuit of the transmitter end provided by the module will be knocked off or crushed in the process of assembling the upper cover

Repair method: replace PCBA

2. Phenomenon description: The RX-ADC value of the module receiving end test is 0. Reason analysis: The RX-ADC value is 0, mainly because there is no photo-generated current.

Maintenance method: ①Check whether the RSSI pin of ROSA is soldered or short-circuited ②Check

Whether the ROSA VCC pin is broken ③Check whether the high-speed signal at the receiving end is short ④RSSI

Whether the foot is shorted to the ground

3. Phenomenon description: the module PCB ground is shorted to the shell

Cause analysis: bad module assembly buckle or device incoming material problem

Maintenance method: ① Check whether the EMI tape on the upper cover of the module is poked or not, resulting in a short circuit with the TOSA shell

②Whether the ROSA feet are short-circuited with the body during the test

③Test whether the TOSA body is short-circuited (there is a case where the EIM tape wire falls into the gap)

Method/Step 2

1. Phenomenon description: TX-LOP ADC Fail

Analysis of the reasons: ① Welding of PD pads on the soft board

②The PD pin of TOSA is soldered

Repair method: re-weld the position of the virtual welding