Labrack

Description

A robust and efficient front panel for standard 1U rackable drawers that provides the following features :

• 2 commonly-used voltage sources :
  • +5V (up to 50W), available on barrel Jack and USB-A connectors.
  • +12V (up to 60W) available on barrel Jacks.
  • Both power supplies have galvanic isolation with the mains voltage.
  • Both power supplies share their DC ground.
• 3 Gigabit Ethernet passthroughs to route the Ethernet cables into the rack drawer while allowing to easily connect/disconnect the drawer from the bay.
• 2 standard 4-pin Intel fan connectors if air cooling is needed.
• A dedicated circuit to simulate a button press when the +12V voltage is applied, this is used to automatically boot a worker machine when its BIOS/EFI does not provide the auto power on feature.
• A screw terminal providing the mains voltage to connect additional power supplies.

Additional parts

All the parts needed in addition to the front panel metal sheet and the assembled PCB.

IEC connector

• 1x screw panel IEC connector Adam Tech IEC-A-3.

Screws

• 2x 16mm M3 screw to attach the IEC connector to the front panel.
• 6x 10mm M4 screw, 4 to attach the front panel to the rack drawer and 2 to attach the handle to the front panel.
• 6x 25mm M4 screw to attach the PCB to the front panel.

Nuts

• 2x M3 nut for the IEC connector attachment to the front panel.
• 10x M4 nuts :
  • 6 are used to attach the PCB to the front panel.
  • 4 are used to attach the front panel to the rack drawer.

Spacers

• 6x 8mm M4 spacer Würth 970080471 for PCB attachment to the front panel.

Washers

• 22x M4 washers :
  • 2 are used to attach the IEC connector to the front panel.
  • 12 are used to attach the PCB to the front panel.
  • 8 are used to attach the front panel to the rack drawer.

Handle

• Handle with a 96mm center axe Inspire Milos 80129371 (link).

Rack drawer

• Thon Rackdrawer 1U (link).

Jack power supply cables

Needed parts :

• 2.1mm x 5.5mm jack to screw terminal Clever Little Box CLB-JL52Y.
• 20AWG cable Alpha Wire 3053 WH005.

Mechanical assembly

PCB preparation

When the PCB has been fully assembled, glue the top side of the AC/DC blocks in order to secure them onto the PCB surface, as they are quite heavy.

Then glue the bottom side of the AC/DC blocks. Also glue the fuses exposed contacts to avoid anyone touching the mains voltage.

Finally, turn the PCB and glue the four locations where the mains voltage is present.

Front metal panel preparation

Peel the protective film from the front metal panel (if any).

Bolt one 25mm M4 screw, along with one M4 spacer and one M4 washer to the bottom-down middle hole. This bolt will later hold the PCB.
The purpose of putting this bolt now is to index the front metal panel on top of the rack drawer bottom plate, because sometimes this drawer is bent.

Attach the front metal panel to the rack drawer

Unpack the rack drawer.
Put the opening side in front of you. The front metal panel will be bolted to this side.

Put the front metal panel in position.

Mark the four front metal panel holes thanks to the punch tool.

Drill the four holes on the rack drawer with a 4.5mm drill bit.

Bolt the front metal panel to the rack drawer, using four 10mm M4 screws, four M4 nuts and four M4 washers.

Attach the PCB to the front metal panel

Add the five missing PCB holding 25mm M4 bolts, along with five M4 spacers and five M4 washers.

Attach the handle to the front metal panel with the help of two 10mm M4 screws and two M4 washers.

Place the PCB in the six bolts with spacers, then bolt it by using six M4 nuts and six M4 washers.

Attach the IEC connector

Place the IEC connector with the longest edge located on the drawer outside.
Bolt it with two 16mm M3 screws, two M3 nuts and two M3 washers.

Cut and strip two 5cm cables of 1.5mm² section. Cut and strip one 4cm cable of 1.5mm² section.

Screw the cables into the PCB power supply terminal block named J1.
The shortest cable must be located in the middle connection of the terminal block.

Solder all cables to the IEC terminal block.
Start from the bottom cable to ease getting access to the yet-unsoldered cables.

Isolate the IEC connector solder joints with hot glue, the goal is to protect an user inadvertently touching a mains conductor.
It is more effective to put the drawer with the front metal panel laying down on the table corner, so the hot glue can cover the whole solder joints.

The mechanical assembly is now complete.