Schematic Teacher Needed (Need help reading Logic stuff)

[jasonsmith]

So on my Stargate I noticed a couple jumper wires on the main CPU PCB. I just want to know what they're doing. I have no idea how to read the Logic Schematic that I think depicts that.

Here is what I know.

I have two wires leaving 5A. One from pin 3 and one from pin 4 I think.



The white wire from 5A pin 3 goes to 6F pin 3.



The yellowish wire from 5A pin 4 goes to a spot on the PCB.





Here are links to the manuals:

Drawing Set - http://www.arcade-museum.com/manuals-videogames/S/stargate-ds.pdf

Manual - http://www.arcade-museum.com/manuals-videogames/S/stargate.pdf

My questions:

1. Did I get the pin locations correct? I think the dot on the chip marks the pin 1 location correct.

2. Where on the diagram can I find the 5A to 6F connection. I looked but it didn't make sense to me to know for sure.

3. Where or how do I find that location to where the other wire goes to? Since it doesn't have a part or anything I have no idea how to find it on the diagram.

I know this is a lot to ask but if anyone would like to teach me the basics here that would be greatly appreciated.

Thank You.


EDIT:

Just found a eBay PCB listing with the exact same mods to the PCB, this must have been a wider spread mod or fix. - http://www.ebay.com/itm/WILLIAMS-CPU-defender-robotron-joust-stargate-UNTESTED-ARCADE-PCB-board-c178-6-/161251501813?pt=LH_DefaultDomain_0&hash=item258b56a6f5

[iankellogg]

the notch is the top of the chip, The "upper left" pin is pin number 1. THe dot doesn't always mean pin 1 and can just be a manufacturing left over. As for figuring out what the wires are doing you need to do exactly what you did, find the chip on the schematic, look for the pin, find where it goes and verify.

[jasonsmith]

Okay Ian so how's this?

The notch and upper left is 1 so did I count it correctly as per the image?

Pending my numbering being correct I have a wire attached to pin 15 of the 374 chip correct? As per the drawing pin 15 connects to "04" on the ?P Data Bus?

on the bottom right circled in green did I find where 15 actually goes to? pin 2 on 1Q



Full Size - https://dl.dropboxusercontent.com/u/85675826/2014-04-09%2020.12.00s.jpg

Now the question still remains... How do I find out what that spot is where the other end of the green wire is (circled in blue above the 374 chip)? I don't know how to find those solder spots on a diagram.

[iankellogg]

what you said is correct. I don't quite understand what you are asking to do with the green wire. If you are trying to fix a broken trace. run the wire directly from one leg to the other.

[jasonsmith]

Just trying to figure out where that wire is going Ian that's all. I didn't put it there it was already there so trying to figure out why its there.

[iankellogg]

Oh I see. It's probably attached to a via that goes to the pin on the other chip. It's not a smart spot to put a wire but that is what it looks like to me