Fifty Cents Nearly Buried the Slow Mo Guys’ 168TB LaCie RAID Storage System

Gavin Free of the Slow Mo Guys bought the LaCie 12big Thunderbolt 3 in 2019 because twelve 14TB 7200-rpm enterprise drives packed 168 terabytes into one desktop tower and Thunderbolt 3 could shove footage across at up to 2600 megabytes per second. That kind of space and speed made sense for years of high-frame-rate video. Seven years later the tower simply would not stay on. Fans sat still. After about ten seconds the whole unit powered itself down. Warranty had expired, the model had been discontinued, and Seagate’s answer was to buy a new one.

Gavin took every drive out of the chassis before it left the studio door, ensuring the archive was as safe as a house, and then dispatched the empty enclosure to Mend It Mark. Mark immediately ran into a problem: there was no service manual or schematics to work with. He began by disassembling the chassis, which is a complicated beast with four cooling fans, a SATA backplane, a 400-watt power supply, and a main board built around an NXP LPC11U6x microprocessor. That gadget controls power and monitors the rest of the system. When Mark turned on the power, a few LEDs lit up, but the majority of the power rails remained dark, indicating that things were not looking hopeful.

Mark worked his way through the power management logic until he ran into a problem with the microcontroller, which was waiting for healthy tachometer signals from the fan controllers on the backplane. When fed directly with 12 volts, the fans spin and drain electricity, so the motors were fine. However, a small SOT-23 P-channel MOSFET, a SI2319 or a similar model designated 819, had failed. Instead of turning off the power properly, it began leaking voltage. The microcontroller had given up on the cooling system and wouldn’t perform much else. Gavin had already attempted a repair on a damaged capacitor with a thermal camera since the solder junction was a little scratchy, but the real issue was elsewhere.

Mark managed to coax the dead MOSFET out with some hot air, install a cheap replacement, and reassemble the tower. Fans were spinning, a blue light flashed, and the unit remained powered on. A comprehensive confirmation check is still required, but the chassis is now operating normally, at least for the time being. A fifty-cent part was enough to temporarily disable a $10,000 storage fortress for 4K and 6K work. If the MOSFET was the only thing that went wrong, Gavin will have his archive tower back for the price of something most people wouldn’t even notice was missing.
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