This Blackmagic Design Smartview Duo came to me with a faulty SDI input on one of the monitors. A quick inspection of the board revealed no obvious soldering issues on the BNC connectors, a cracked/cold solder joint here would be an easy repair but unfortunately not in this case!
This monitor had failed in the field at a venue with a suspected faulty electrical installation with bad earthing. Knowing how sensitive SDI I/O can be to ESD I quickly suspected the input circuitry may have taken a shock and failed.
Powering on the monitor for a functional test, my initial thoughts were confirmed by a large amount of heat buildup on an IC near the SDI input connector. A Texas Instruments LMH0341 “SDI Deserializer with Loopthrough and LVDS Interface”.
Interestingly the SDI input does not connect directly to this Deserialiser IC, the incoming signal is first passed through an equaliser. The SDI loop output uses the cable driver built into the LMH0341 and I believe this is where the ESD that took the IC out has originated from as the monitor was racked next to (and directly connected to) an Atem switcher. The loop output, however, was used to drive further displays within the venue.
With the LMH0341 replaced, the monitor started working again with full functionality including the SDI loop output.