PCB - Ground question

[Brabus]

I have a pcb with a soldered connector to the ground pins, which then connects up to the power supply in my cabinet.

My questions if someone knows are, why it was done like this? does it need that connection to be ok or is it just an extra precaution? and would I be ok to put another board in that doesn't have that extra ground connection added to it?

I think from the images my edge connector does have ground on it already.
The plug in the image connects to the pcb soldered on plug and the wire just heads back to the power grnd

 

[qjuk]

If you look closely at your edge connector, the second ground pin from the right is burnt up. Someone has bodged the extra wire to ground to compensate for the burnt pin.
GND draws a lot of power, so you need the extra/thicker wiring for ground. Either keep the wire bodge as it is, or fix up the burnt edge connector with copper tape and a bit of solder, then you can do away with the bodge.

Edit to add: You can plug another board straight into the black connector (obviously make sure the board uses the same pinout! - or use a suitable adapter). However, I would check the pins inside the black connector to make sure they look good and not damaged/pushed back. If this connector was the same one that burnt the edge on your Konami board it suggests the contact pin/s inside the black connector are not great. A loose connection/poor contact can burn up edge connectors. If the back connector doesn’t look great, I’d replace it.

 

[Brabus]

Thanks for that, really helpful. I hadn't looked too closely and it probably prevented me from just trying another board in there right away. The second edge connector on the pcb is pretty much gone i think after looking from what you said. So think I will keep the bodge for that board, and save a little time since it should work.

I will investigate the edge connector, hopefully the previous person fixed any issue with it before installing the bodged wire to get the board working. Im assuming if all is ok with it, then the wires in there should be able to handle any power draw required? and no need to solder a connector to that board too.

 

[Brabus]

So it looks like the first pin which i think is +5v got hot and melted the plastic. Can see this in the images where its bubbled up and the contact stuck in plastic depressed down. Cleared a bit of it, then used a soldering iron to push it through and back into a position where it should make contact. Why would the ground pad burn, I'm guessing a potential short?

For some reason it also appears one of the ground wires was snipped off from the connector. So just 3 not 4 connected

Wondering what i need to do to make sure its all ok. test it for shorts and probably should connect a new ground wire back in if i can?

Sorry about the quality of the images

 

[qjuk]

Melted pins is a sign of poor contact and not a short. If the connection between the pins and pcb edge is not tight/firm/has oxidation it creates resistance which then in turn creates heat and melts/burns things up.

The pins in your black connector look quite crusty. I think the best solution in your case is to cut it off and solder a whole new connector.

 

[Brabus]

The gunk on the pins I think is paint dust settling. Havent cleaned anything yet. But you might be right, better to replace the connector. I think I need to add that other ground wire too, so doing that on the current connector i dont think would be fun, and im probably not going to trust that first +5v pin much anyway.

 

[Spanky]

Replace that edge connector.