USB DC Power Blocker

Some printer control boards receive power via USB when connected to a PC or OctoPi, which forces the printer's control board to stay powered on even after the printer has been turned off. This is a nuisance when you want to turn everything off (hard reset, firmware update, etc.), so a DC blocker is handy to have. 

This model is a 2-part case that holds standard PC-mount (printed circuitboard mount) USB A connectors (male and female). The 5V DC pin is removed on both connectors and the other pins are soldered straight through. 

Tips on Assembly:

Parts:

• use standard PC mount USB male and female connector parts
• print one complete set (body and lid) for each USB DC Blocker you intend to make

Preparation:

• plug/join the male and female connectors together at this point
  • makes removing the correct pin easy to track
  • see the USB pinout to identify the 5V pin
• remove/pull the 5V DC pin from both the male and female connectors
• bend the PC mount tabs flat (see pictures)
• carefully bend the remaining pins out flat (see assembly pictures)
• put the unsoldered connectors into the body
  • dry-fit the lid to set the spacing before soldering
  • bend the pins as required to make soldering easier
    • i.e. they should be touching and aligned with each other

Soldering:

• place a small dab of solder flux on each pair of pins (optional, but recommended)
• use as little solder as will do the job
  • don't bridge solder between the pins
• after soldering the top, remove the assembly from the body 
  • lightly solder the bottom of the pins
  • make sure you have good solder flow all around
  • allow each pin to cool fully before flowing the next one
    • otherwise the spacing/shape will be lost

Testing (before final assembly):

• connect DC blocker into OctoPi, plug USB cable into DC blocker and connect to printer
  • printer→USB Cable→DC Blocker→OctoPi
• make sure you can still connect to the serial port
  • perform homing operations, etc
• If trouble, check with multimeter/continuity beeper
  • make sure all 3 signals are connected between USB connectors
  • make sure there are no shorts between pins
• Test that powering off printer also powers off the board

Final Assembly:

• Place the soldered connector assembly back in the housing body
• carefully put a dab of hot melt glue into/onto the middle of the connector assembly
  • careful not to use too much
  • use work gloves (cotton or leather) to avoid nasty burns from the hot melt
• quickly push the lid into place and hold tightly until hot melt hardens
  • make sure  the tabs go into the right recesses on the connectors

Re-test. If it still works, you're done.