PON SERDES - LVPECL interface failure

[tf_summer]

serdes lvpecl

Hi
On my PCB, I got a ethernet PON SERDES that connect to a Optical Module(OM) via LVPECL interface.
1.25Gbps, 130R + 82R Resistors DC terminated at Recieve direction

And there is 5 OM available , 3 of which are the same type of brand H , while the other 2 are of brand F.
Now, only the specific one OM of brand H is working well on board, with out any CRC error reported by MAC laying over SERDES.
CRC errors are always detected by ethernet PON-MAC when the other four OM are running on board.
Since there are only two boards to work over, I guess it's better not to make any modification to the vunerable PCB before thorough analysis
So I came to here for brain storming , from which I wish to extract some approach to go on to next, thanks

 

[jeyaraman]

Did you compare the drive capabilities of both the optical modules?

- jeyaraman

 

[huang_yixiong]

for fiber module, the matching resistor has been included in module,so the exteranl match rsistor NOT need.for the serdes phy, the different chip need the different match resistance,u can refer the detail chip datasheet.