Main > Main Forum

Issues with MC Cthulhu in an arcade stick

<< < (2/2)

PL1:

--- Quote from: Skivt68 on June 15, 2013, 11:40:28 pm ---cutting all of the traces near the switches by scoring the board with a utility knife should work, correct?

--- End quote ---
It SHOULD work, but it's much better to remove a small section of the trace to ensure there's no chance of reestablishing an accidental connection if something brushes against the cut trace and pushes it into contact again.

I remember years ago working on this one PCB.

When you'd test it with the ohmmeter, it looked normal, but when 5v was applied, it shorted.

Over the next month, several others attempted to repair the board, but weren't able to isolate the problem.

Turns out that one of my coworkers was a bit sloppy when doing the initial trace repair/soldering and epoxy backfill.

I found a series of microscopic solder globs in the epoxy that provided a path for the higher amperage 5v supply to arc over, but not for the very low amperage ohm-meter.

Once I carefully excavated the solder globs and re-epoxied it, the board worked fine.


--- Quote from: Skivt68 on June 15, 2013, 11:40:28 pm ---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?

--- End quote ---

Does it still do that when you disconnect all other control wiring and use a piece of wire to short select to ground? (removes all other variables and tests just that input on the board)

I'm not familiar with the MC Cthulhu encoder, so I will leave any further in-depth troubleshooting to others.   :dunno


Scott

Skivt68:
Alright, so i put only 1 button on the select and viola! it worked.  Now i just have to deal with the issue of cutting the traces. Do you think that instead of cutting the traces, (as they are tight and plentiful) I could remove all of the IC from their sockets?  I assume that that is what is keeping them encoded/linked.  i will try that now and get back to you guys if it works.  Let me know if you think that that would disrupt it though, as i can also remove any components on the outside of the board.
EDIT:
Update: removed to ICs, didn't do anything to help with the column issue, but now the select button works.  I'll get out the soldering irons and flush cutter later and remove all components on the board save for the buttons and if that doesn't work, i'll try to cut the traces.

Skivt68:
Hey, sorry for the double post, but, i have removed all components save for the switches from the board, but in the process, i had to cut some joined resistor banks.  I didn't touch them much, but I was wondering if it is harmful to gut a resistor/ceramic capacitor.  I will have an update soon after I test it  just continuity tested the board, Scott, your are indeed right, the signal wires of all of the buttons in a column are indeed joined by traces.  i will be cutting the traces once I have the time.

PL1:
If you cut all the row connections or all the column connections, you can use the uncut ones as a daisy-chain ground -- less soldering that way.   :cheers:


Scott

Navigation

[0] Message Index

[*] Previous page

Go to full version