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How a PS2 dual-shock gamepad PCB works?

Discussion in 'Electronics & Electrics' started by elvis, Nov 12, 2006.

  1. elvis

    elvis Old school old fool

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    I've got some bare PS2 gamepad PCBs with just the encoder on it, and a cable to the console. No motors, and no analogue thumbsticks:

    http://66.221.218.31/arcade/ozhadou/sf007.jpg

    When plugging these into a PS2, the console won't boot. I can plug a genuine Sony pad in, boot from that, then plug one of these PCBs in later and the system detects it fine, however the inputs from the non-existent analogue parts are pretty haywire. It seems that 0V returning from these parts puts my left analogue stick into full-bore up-left, and all sorts of weird results get returned from the right one.

    Does anyone know how these work? I assume I need to throw some pots on the X/Y axes to simulate an existing thumbstick. I've experimented a little but haven't had much luck getting a consistent result. I've got another dual-shock pad that I've measured which reported 2K ohm on the thumbsticks, but silly me measured these on the device which obviously gave me incorrect results. Buying some 2K vertical trimpots and adding them to my controller PCB gave me a reading of 1K when they were in-circuit. :o

    Anyways, if someone can shed some light on this, I'd be greatful. I'm kind of stumbling in the dark here, but if anyone knows some specifics please share.

    Eventually if I can find the exact value I need, I'd like to throw permanent resistors in to give me the "neutral" values of the stick. I only need the pad to work in digital mode when it's done (for simple fighting games), so I just want the analogue parts to be on (so the console can boot without having a cow), but not in use.
     
  2. Goth

    Goth Grumpy Member

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    So you're making an arcade-style controller or something? Cool, i've been meaning to do just that.

    Try measuring the resistances of the analog sticks without having them connected to the device - you'll need them removed from the PCB.
     
  3. OP
    OP
    elvis

    elvis Old school old fool

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    Yeah, that's what I ended up doing. I ripped apart an old MadCatz pad I had lying around. 100K-ohm pots. I just happen to have some of those lying around, so I'll chuck them in the PCBs and see how I go.

    Doing 2 things:

    1) Wiring up my new arcade cabinet to my PS2

    2) Producing custom desk/lap top arcade joysticks for consoles and PC/Mac/USB. Website coming soon. :)
     
    Last edited: Nov 12, 2006
  4. OP
    OP
    elvis

    elvis Old school old fool

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    No joy. Wiring up the 100K pots and mirroring the case grounding of the thumbsticks still gives me whacky input from the analogue parts. So far the effort has not been worth the reward.

    Oh well. This was me hoping I could use $1.50 chinese made PS2 gamepad PCBs instead of paying $20 for retail controllers and hacking them. At least it was a cheap experiment. Although now I have 20 PCBs and nothing to do with them. :)
     
  5. NerfDude

    NerfDude Member

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    You might be able to find an original ps1 controller that has no analog sticks, dont know if these work on a ps2 though..
     
  6. OP
    OP
    elvis

    elvis Old school old fool

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    I imported a truckload of PS2 controller PCBs from China in the hope that I could use them for a bulk stick-making project I have in the works. Price per unit was ridiculously cheap, so it was a nice way of shaving a few bucks off each stick's build cost.

    Unfortunately that didn't quite go to plan. :) Not to worry - there's a place around the corner from me that sells genuine Sony stuff second hand for reasonable prices.
     
  7. TERRA Operative

    TERRA Operative Member

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    Try using 4k resistors across where the pots would go. (2 resistors per pot)
     
  8. OP
    OP
    elvis

    elvis Old school old fool

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    I'll give it a whirl. Where did you get that data from?
     
  9. TERRA Operative

    TERRA Operative Member

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    Measured the pots directly on the pcb. I dunno if I am reading circuit resistance too though.
    I just measured the analogue sticks from an Xbox controller (out of circuit) and they came to between around 5.5K and 6K.
    My bro posted a pic with a diagram on some other forum. I'll see if I can get it if you want.
     
  10. OP
    OP
    elvis

    elvis Old school old fool

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    I did the same at first, and got very incorrect results. In-circuit I was measuring around 2K. Desoldered them and measured them out of circuit, and they were 20K.

    Being analogue controls, most of the pots are connected to almost every other bloody input in the entire circuit. Very frustrating to try and find any sort of data from the circuit.
     
  11. TERRA Operative

    TERRA Operative Member

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    I'm not sure my brother wants to desolder his gamepad... but if you have the analogue sticks removed, just measure them between the centre pin and outside pins in the home position and stick resistors in of the same value.
     
  12. OP
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    elvis

    elvis Old school old fool

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    Yeah I did that. :)

    Trimpots have a constant resistance between the outer pins, and a variable resistance between the center and outer pinds depending on position. And again, these all need to be measured out of circuit.

    Please don't destroy your own gamepads for my sake. I was just putting the question out to see if anyone knew what the values where, if they had done this before.
     

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