Update: Replacement of Fan Hubs in Torrent case series (08-31)

21-08-31  21:30 CEST

General update and background

We would like to share some additional details on the issue itself, actions taken and the revised design of the PCB.

One of our first actions was to investigate the prevalence of this issue in produced units. Our team tested 479 Torrents from the same SKU and found the issue in 8 fan hubs, a failure rate of 1.67%. While the sample size is relatively small, it allowed the following observations and conclusions:

This issue has two stages – first an assembly problem and then insufficient precautions in the PCB design.

The fan control PCB on the torrent case has no alignment feature that ensures that it sits directly on top of the mounting studs, and visibility into this area is limited. On a small number of Torrent cases the fan hub screws have hit the PCB surface, while turning at high speeds through the use of power tools in case assembly. This scratched away the black lacquer and exposed the copper trace below. The damage may or may not be visible with the PCB in place in the chassis, we have seen both cases with damage on the lacquer layer extending beyond the screw head and cases where the damage is entirely hidden below the screw head. 

Unfortunately, the exposed copper is connected to the 12V input. Having the 12V copper plane so close to the mounting screws is bad design practice, the area directly below the screw head (with some margin) should have been disconnected or grounded. This makes no difference as long as the lacquer is intact, but is a good precaution in case the lacquer is damaged.

In most cases this issue triggers the short circuit protection in the Power Supply, immediately turning the computer off without permanent damage (the PSU may need to rest a few minutes for the protection circuit to cool down). 

But this can also lead to issues that are harder to detect, including slowly melting cable insulation. This led to our decision to halt sales and strongly recommend even users who have experienced no issues at all with their Torrent fan hubs to disconnect them and request a free redesigned replacement board. 

New PCB Design:

In order to address these issues, we’re making the following updates to the PCB design.

  • VCC, RPM and PWM main traces are now all on the back side of the PCB. VCC traces are still wide enough for 3A total.
  • Front side of the PCB contains small bridges for PWM & RPM, to carry them over the VCC trace.
  • Screw holes are now plated-through (they are not connected to GND to avoid the possibility of current travelling through the case if GND wire is disconnected).
  • Screw hole diameter increased slightly to allow placing PCB on standoffs with raised collar for alignment in future production. 
  • Entire remaining surface of front and back connected to GND.
  • VCC & GND removed from PWM MB connector (to avoid a potential issue when PWM connectors are inserted the wrong way into MB header).
  • PCB height increased 1.5mm, gaining more space between screw heads and nearby soldering points. 
  • Version number added at bottom corner for easy identification.

Update on Timeline:

Regarding the timeline we’re working with, we’re taking some actions to meet the aim of having the first replacement kits ship to customers within 2-3 weeks. 

We aim to produce a sufficient number of V1.1 fan hubs in the first batch following these updated specifications, to service all existing customers. 

This is done in order to expedite the process of having replacement kits reach Torrent owners. The lead time for producing the necessary quantities is almost the same as for producing only a handful.

When the first production batch of replacement kits is ready, we will ship the units directly to our Customer Care centers. As our HQ in Sweden also houses one of them, our engineers will put enough of these replacement kits through rigorous testing and analysis, to determine that they are meeting Fractal quality standards and are ready to ship to customers. 

This means that on the same day we approve the V1.1 boards at HQ, our Customer Care teams around the world will be able to start shipping replacement kits to customers. 

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