The diodes need to be in line with the button wires.
The anode should connect to the hori button signal. The cathode connects to the button wire and to the xb1 mkx button signal.
Just for reference
So basically (the xbx signal + the button wire) connects the cathode and the anode goes into the hori pcb button signal? That means this process cannot be done on the top side (picture above says the top side of the pcb) of the pcb unless the wires are removed from the bottom?
Here you go, do this for all button/directional signals as well as the following:
Home - small white
Switch - green
Share - purple
https://dl.dropboxusercontent.com/u/1570228/How%20to%20wire%20Hori%20RAP%20Kai.jpg
https://dl.dropboxusercontent.com/u/1570228/2015-06-29%2001.43.05.jpg
Thanks alot guys, each and everyone of you. Working fine now. I will post my mod as soon as I complete it. I work 14hrs a day and fasting these days as well (4 hrs sleep 
), hardly any time to do anything.
Here’s my web of awfulness.
Spoiler
Btw, does anyone know how to light up the led on the hori rap4 kai when pdp xbox 360 gets recognition?
Get some zip ties and get rid of that rats nest.
As for the indicator LEDs? I found it was best to leave them alone.
Its possible, but SMD leds are a pain to solder too
Find the wire for the LED and run a line to it from the LED of the pad
I did and it turns the LED always on. Regardless of which pcb is recognized, the LED remains lit.
Use the other side
Wait, are you trying to have the light off for a certain system? I’m confused
Yes. I only want it to lit when xbox pad is recognized (or xbox 360 for that matter)
That’s weird but ok. De solder the 2 wires for the LED and solder them to the pad
Can someone please point out the LED1, LED2, LED3 and LED4 points for the xbox 360 on this pad?
Thanks.
They’re on the front; you’ll know them when you see them
Noticing another odd thing with the MKX PDP pcb. I’ve only have had it happen on the XB360 side, but very very occasionally the controller will “disconnect” and reconnect instantly. It has happened on my XB360 and on my PC playing fightcade. Fairly annoying. Anyone run into this?
While dual modded or by itself?
I didn’t test it a whole lot by itself. It is currently dual modded with a Hori HRAP v5 PS4 stick.
I found PDP MKX to be a very dodgy pad. At first i was having trouble keeping it in neutral as sometimes it remained in one direction until you press any other direction or even a button to reset it back to neutral.
Never had disconnection issue (maybe once it completely disconnected which i had to plug out and then plug back in but other than that I cant recall any disconnections).
Now the pcb is totally dead maybe its because of Hori RAP 4 kai grounding all the signals on the other pcb, maybe something else happened, not sure. I have bought another one from ebay and will try to dual mod it with a guilty gear xrd sign fightpad. let’s see how it goes.
that’s never happened to me in all of the 20+ pads i’ve used