Power issue (NES EXP)

Started by Dark_human, September 20, 2016, 06:45:47 am

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September 20, 2016, 06:45:47 am Last Edit: September 25, 2016, 02:21:40 pm by Dark_human
I've connected controllers to the EXP port on the bottom side of my NES. The controllers work great, however if I attach an LED to the equation, it lights up (only if controllers are connected) and makes the controllers unresponsive.  Any idea what I'm doing wrong??  Thanks in advance.


Without pictures or how you're connecting the LED it's impossible to find out what's wrong..


They are daisy chained straight out to the exp port. I'm adding an led between +5V and ground, with a resistor.   If I remove the led & resistor controllers work great. If I wire it straight to the back of an snes controller port PCB (the one with the onboard led/resistor) it lights up and kills my input still. Can add pics soon


Try it without resistor, usually the LED doesn't burn (eventhough it's not healthy either). Most likely error with resistor cause of controller latch, if I'm not wrong.


September 20, 2016, 10:41:34 am #4 Last Edit: September 20, 2016, 07:35:12 pm by Dark_human
Hmm, interesting.
Adaptor from exp

Connected straight into NES controllers...

Then into the snes controllers...

The led that messed everything up. Cut the +5V and my NES controllers work again

Post Merge: September 20, 2016, 07:35:12 pm

Removed the resistor. Led lights up only when controller is inserted and still doesn't work.


Update: I pulled the resistor and the led still lights up, and it's still messing up the controls.
The led is removed, NES p1 & p2 work. Snes controllers almost work --> so I found my voltomiter and this is what I've learned. The exp port without anything hooked up outputs 0V.
Connect a single NES controller gives you 2.8V from the 5V line. Not enough to power a single NES controller. Almost: three inputs work. Mario could run right and jump. Jumping while shooting down right in contra will trigger start. Excessive button inputs trigger a change to clock. (Connecting 5v to clock in contra for example fires a shot. )
Connecting a second controller draws 3V. Enough for either controller to easily work 100%.
NES max controller needs more than 3V and still doesn't work right.

Connecting a SNES controller alone draws under 2.5V. Not enough to do anything than make a change to clock with any button press (single shot fired).
Adding a NES controller brings it up to 2.5V(likewise adding a snes controller with a 2.8V nes controller drops it to 2.5). Enough to nearly control using the snes controller, but still changes clock to trigger start. With 2/NES and a snes controller plugged in there's still a voltage drop that messes up the NES controls. But only on the same controller.

No wonder a single led would draw all the power from the line. Any EXP port output needs a voltage amplifier/regulator.  Adding that next