GND connections

Discussion in 'General Electronics Chat' started by Johndon2000, Jun 12, 2013.

  1. Johndon2000

    Thread Starter New Member

    Jun 12, 2013
    25
    0
    Hi,

    I am bench testing a cct board and the edge connector has 42 pins to GND (all distributed in random places over the connector!)...

    I'm sure it's not necessary to connect all 42 pins to GND to simply test the board (for voltages, clocks, resets etc)...

    I guess if I connect 10-15 pins to GND this should be sufficient, or is that a mistake?

    If so, how many would be sufficient (as it is time consuming every time I test a different board!)

    Thanks,

    John.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,054
    3,245
    Are all the grounds connected together on the board?

    If you are not testing critical parameters than you may not need to connect all the grounds.

    Since it's an edge connector why not just wire up a dedicated mating test connector will all the grounds connected together?
     
  3. JMac3108

    Active Member

    Aug 16, 2010
    349
    66
    I suspect that what you have is that some number of those grounds are power returns, and the rest are for signal shielding (preventing crosstalk, EMI, etc.). They are probably all connected together (easy enough to check with a meter). But, if some of those grounds are shielding, they may go to small traces that parallel the signals (this is common in high speed designs). You want to make sure that your power return is connected to a good ground, and not to a small shielding ground. I would take a close look at the board you have and try to see how the traces lay out on these ground pins.
     
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