DMHUB-MB-0001

This Field Change Order (FCO) addresses an overheating issue in DEChub 900 MultiSwitch (DMHUB-MB) products with serial numbers AS421nnnnn to AS439nnnnn, manufactured between June and October 1994, including DMHUB-MA spares.

The problem stems from an out-of-tolerance mechanical fastener scheme with the Power Distribution Module (70-30820-01) board, causing it to overheat. Symptoms include short-circuiting, hub non-operation, localized melting and deformation of the product enclosure, discoloration, unpleasant smells, and smoke production. While these effects can be dramatic, the document explicitly states there is no danger of electrocution or fire, and the issue does not affect the safety of the product.

The solution is to replace the Power Distribution Module Assembly (70-30820-01) from revision A02 with revision B02. The FCO kit (EQ-01740-01) includes the new Power Distribution Module, cable clamps, a tie wrap, an upgrade document, a pin wipe kit, and a revision label. The procedure involves disassembling the hub, replacing the affected module and other components from the kit, applying a new revision sticker, and reassembling it, with strict adherence to ESD safety precautions. Material for this upgrade is provided free of charge for all customers under warranty. Digital field engineers are required to report this activity using LARS forms.