So that's what a master system pad looks like inside. For what I'll be doing with it today it's absolutely perfect. I'll be re-wiring this for use with a Sord M5.
The M5 joypad circuit needs a distinct common connection for directions and buttons. Having the separate button and pad PCBs is a gift.
So desoldering ensues.
There still needs to be some track cutting, the buttons should have no common connection. I'll need to interrupt the common and re-route it to one of the solder pads stage left.
Scratch 'n' Snipp. I've noticed at this point that the bottom left pads are conjoined. I'll have to see to that.
OK. Pads separated, jumper wire in place and the required diodes fitted. Ready for wiring now, we are ... almost. The fire buttons are connected to UP and RIGHT connections. The pads work by having 2 wires as selectors. By asserting one after the other either the pad or the buttons can be checked. The diodes prevent the buttons from interfering when it's time to read the pad.
OK. NOW it's time for wiring.
Now there was some devilish detail that I somewhat conveniently glossed over in the previous interstitial texts. Like the fact that the copper-exposing-scratching for the jumper wire was done in a very particular place. The surround of the little rubber contacts was carefully avoided. Did you wonder why the line was drawn on the PCB earlier? You did? Give yourself 5 extra points for observation. Very good.
The button PCB sits on a little rectangular plinth inside the case, so the additional wire needed to be placed so it doesn't foul.
With all that done the replacement cable is soldered.
The pad case has an internal cable restraint, very nice. Just make sure enough outer sleeve is cut from the cable so that the serpentine capture of the cable can sit snugly in the allotted cavity.