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Issues with MC Cthulhu in an arcade stick

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Skivt68:

I just sent a message to Toodles on SRK about this but then I realized that he hasn't been active for 4 months.  Here is what I sent if anyone can help me with this:

--- Quote ---Hi, I just bought one of your MC Cthulhu boards from focus attack and, first of all, it's great, but I have been having some problems. I have all of my buttons ground connections daisy-chained and connected to one GND terminal, and a separate daisy-chain for my joystick, hooked up to a second GND terminal. When I hook up my joystick it is fine, the same goes with hooking up buttons to 1p, 2p, and 3p. When I use more than 3 buttons, however, some buttons will resister as pressing two different buttons at once, such as pressing 2p registers as pressing 2p and 2k, or pressing start registers and pressing start, 3k, and 3p. Also, whenever I connect any button to the terminal for "select" the board no longer registers with the computer and when i remove the wire form the "select" terminal, the board works fine again and registers, save for the multiple button issue mentioned above. I was wondering what you thought the issue might be, and if it can be diagnosed/fixed or if I would just be better off returning it to Focus Attack to exchange it for another MC Cthulhu? I am in no rush, as I still have about 26 days left in the return/exchange window, but any answer would be much appreciated.

Thank you for your help and have a nice weekend,
Skivt68
--- End quote ---

I don't have pictures of my wiring right now, but I can take some if your guys think it might help in diagnosing the problem.

PL1:

When in doubt, include pics.  :cheers:

Have you ohmed out your harness wires and buttons to check for shorts?
(disconnect from the encoder first so you isolate your testing to just the wires and buttons)

Ohm from one wire to another using a pattern like this:

Gnd-1, Gnd-2, Gnd-3, Gnd-4, Gnd-5, Gnd-6
1-2, 1-3, 1-4, 1-5, 1-6
2-3, 2-4, 2-5, 2-6
3-4, 3-5, 3-6
4-5, 4-6
5-6

With no buttons pressed, it should show an open on all readings.
-----------
Connect one lead to the ground wire.

Hold one switch closed and ohm to each wire in turn -- it should show an open on all readings except the wire connected to the switch you are holding closed.

Repeat for each switch in turn.


Scott

Skivt68:

Thank you for your advice, but I'm not sure i know what you mean by "ohm-out".  EDIT: I somewhat get it, but by 'ohm-out" do you mean continutiy test on a multimeter?
I do have plenty of pics of my highly unorthodox lighting controller gone arcade stick.  ;D
It used to be in my school's auditorium, but we didn't need it anymore,and being one of the head student engineers I sometimes get surplus gear.  I took out the dimmer and put in the joystick while flipping the buttons to make them easier to press. After i get the buttons to work, i am planning to add three square buttons from the old dimmer board back into the holes by the joystick as select, home, and start.  that is on hold while i find a mounting solution for those.  In the end, 8 of the 9 grid buttons will be hooked up in addition to the three buttons that will be near the joystick as the MC Cthulhu has room for only 11 buttons and 9+3=12, so i'll just not hook up one of the 9.







The Joystick (white is ground, the rest are the 4 signal wires.  This works fine.)


how I have it working right now (sometimes doenst work if I nudge the encoder/wires as i'm screwing it back together.)


My ridiculously tedious wiring job.  I used a multimeter to check the daisy-chain, if I press the first button in the chain (top right) the ground is active on the last button in the chain (bottom left).  The pcb around the buttons is not part of the setup and is just there to hold them in place.  Should i cut the traces on it just to be safe?  (for this, the white and black are daisy chained ground and the green ad red are the various signal wires.


PL1:


--- Quote from: Skivt68 on June 15, 2013, 09:48:20 pm ---by 'ohm-out" do you mean continutiy test on a multimeter?

--- End quote ---
Yes.  Continuity means a resistance of less than ~2 Ohms between two points.

I phrased it that way since not all multimeters have a setting for "Continuity", but they all have a setting for "Ohms".


--- Quote from: Skivt68 on June 15, 2013, 09:48:20 pm ---highly unorthodox lighting controller gone arcade stick.  ;D

--- End quote ---
You are truly gifted in the fine art of understatement.  :lol


--- Quote from: Skivt68 on June 15, 2013, 09:48:20 pm ---how I have it working right now (sometimes doenst work if I nudge the encoder/wires as i'm screwing it back together.)

--- End quote ---
You will need better mechanical and electrical connections using solder and/or quick disconnects.

Also, you'll want to insulate the metal case to prevent accidentally shorting the wires -- some spray paint or adhesive shelf-liner should do a decent job.


--- Quote from: Skivt68 on June 15, 2013, 09:48:20 pm ---The pcb around the buttons is not part of the setup and is just there to hold them in place.  Should i cut the traces on it just to be safe?

--- End quote ---
The red PCB holding the buttons looks like it has a built-in encoder circuit -- probably a matrix-type encoder -- that decodes buttons wired in rows and columns like this Atari 2600 Keypad.



if you can cut the traces so the only things electrically connecting to each button are your ground wire and signal wire, that would be the best way to proceed short of desoldering the buttons and remounting them on perfboard.


Scott
[/post #2000 :woot]

Skivt68:

Thank you so much!  Congrats on 2000 posts!  :cheers:
I'll have to get to work mutimeter testing tomorrow.  Also, cutting all of the traces near the switches by scoring the board with a utility knife should work, correct?
 I think that this might be the underlying issue, as the 7 button (labeled "S7") had it's solder pads lifted from the board when I was desoldering it to test which leads were ground and signal. (which in retrospect i shouldn't have desoldered it for, but oh well)  The middle row of buttons that are hoked up, and the 7 which had its pads lifted, all work because they are in a row, not columns, making them electrically separate. 
One last question, why do you think the computer will not recognize the board when "select" is connected, regardless of the button it is connected to?

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