VICOR VIPACK power supply connector defect

Defect Report
Vicor VIPACK power supply connector

John Nagle
October 6, 2004

On October 3, we experienced a failure of 24VDC supply A. We discovered that the connector supplying 120VAC to the power supply was intermittent, for reasons that are difficult to fix in the field. This is our analysis of the problem.

This page is addressed to Vicor engineering personnel.

	An overview of the Overbot's power box. The cooling fins projecting through the top are part of the VICOR VIPACK power supplies. The box sits on shock mounts in the back bed of the Overbot, a modified 6-wheel drive off-road vehicle. The 3KVA generator visible at the right rear provides AC power to the power box.
	Inside the power box, with the lid open. Three VIPACK power supplies are installed. The center supply provides 2 20A 12V outputs, while the supplies at the sides provide 24VDC 20A each. Vicor VIPACK power supplies were chosen as being the most rugged offering from Vicor. The power box was designed around these power supplies, with the large fins attached to the cold plate projecting through the lid.
	Detail of the trouble spot, the input power connector to the left side 24VDC power supply. This is the connector that became intermittent.
	Markup of the drawing of the connector. The connector can wiggle vertically, causing intermittents, and when vibrated, it does.
	End view of the connector. Note the lack of support below the connector. The board-mounted connector is supported laterally by the posts, but the posts provide no resistance to vertical deflection. Any vertical deflection is resisted only by the connections into the blue spacer (not visible) into which the connector is mounted.
	Our temporary workaround - a plastic shim.
	The plastic shim in place between the connector and the cold plate. This provides extra support for the connector. The cable tie keeps the shim from sliding out. We would like a more permanent solution from VIcor.