Power Supply Plug

[IronRingReno]

I am putting a new 5 pin DIN plug on a switching power supply for a KVM Switch. The label on the power supply provides the following information.

Pin 1: Ground
Pin 2: Common
Pin 3: +5VDC
Pin 4: -5VDC
Pin 5: +12VDC

With my voltmeter I can find the +5VDC, -5VDC and +12VDC voltages. They are on colored wires.

However, both Ground and Common appear to be black wires.

Is there a problem is they get switched when attached to the new 5 pin DIN plug?

 

[automatic2]

open it up and trace the leads back to the board. Do the traces connect?. Typically they do but not always. KV supply would have me checking.

 

[IRstuff]

You should be able to measure the resistance between the common and ground. It's most likely that they're tied together in the power supply.

TTFN

 

[melone]

Isn't common, a non-current carrying node?

 

[IRstuff]

Normally, if one were to do this "right" for proper EMI and noise performance, the individual power rails would have individual returns, which are then all tied together at the supply. Likewise, at the power supply, the external ground might be tied to the returns to ensure that there are no transient conditions resulting in a shock hazard.


This configuration allows PC's to be connected together through RS-422 and other direct connections without risk of damage during start-up conditions.

TTFN

 

[IronRingReno]

I opened up the power supply to trace the common and ground wires. While they terminated at points close to each other on the board, I couldn't see if they or their traces touched. There were to many other components in the way and the botton of the board has a second board mounted closely on stand offs.

However, I noticed a capacitor near the power LED that looked like it has been toasted. I guess that I should stop messing with the plug and find a new power supply.

Thanks to all who responded.