PC Engine 6 button controller

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mourix:
Maybe it's a good thing to go put select directly to VCC with a wire to see if it still triggers accidentally.

pbj:
Well, if I put select directly to Vcc, and then I ground out select, the console scrambles the graphics and freezes up, so that is a no go. If I just leave it connected to Vcc and wait, after a few seconds the system registers a phantom select press. I still get a select input when I plug in the controller cable with the system on.

lilshawn:

--- Quote from: pbj on August 17, 2023, 04:50:50 pm ---I do actually have a logic probe. Can you type very slowly and tell me what I should do with it?

--- End quote ---

sorry, i didnt see this post. i can help you out here a bit.

you probe should have some power lead on it. (one or two, either a power and ground, or just ground) hook this up to your circuit.

your probe should have a setting for TTL/CMOS. (For TTL it is 4.75 V to 5.25 V while for CMOS it ranges between 0 to 1/3 VDD for a "low" level signal and 2/3VDD to VDD for a "high" level signal. set your probe for CMOS mode.

your probe may or may not have a switch for "pulse" or "mem" or the like. this will just illuminate an led for if it senses a logic level change that is extremely short. it will lock on a light or have it flash or something like that. you usually have to apply the probe to the circuit, then turn on pulse mode to keep from it being triggered by attaching it.

then just attach your probe tip to your circuit inputs and outputs to see where your weird pulses are coming from. make sure your button presses are properly registering as high and low and not "both"

couldn't hurt to check to see if your +5 vcc coming in to your board doesn't have a pile of ripple on it. measure it with your voltmeter set to AC. it should be less than 20mv. if it's higher, you have some bad power filtering somewhere in the console sending dirty power.

--- Quote from: pbj on August 22, 2023, 12:13:53 pm ---Well, if I put select directly to Vcc, and then I ground out select, the console scrambles the graphics and freezes up, so that is a no go.

--- End quote ---

kek, you essentially shorted your VCC to ground if you don't do it through a resistor. not sure why mourix suggested this.. maybe thinking your board had a seperate or different supply maybe?

pbj:
Reading 1.5 - 2.6 mV AC. Readings didn't do much even when loading large roms or booting a CD. Oddly, even with the system off I'm still reading 1.4mV. :dunno

Still digging around for the logic probe. I bought it back when I was trying to fix some Williams pinball boards with a test rom. It passed all the tests beautifully but wouldn't boot. I bought repros. :lol

lilshawn:
voltage seems good, not much ripple there so I don't think it's that.

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