CMR Posted March 26, 2022 Share Posted March 26, 2022 How essential is it that these need to be 620 ohms? Can they be a little over? It looks like they're just holding pins 5 and 9 high until the switches pull them low. Specifically I have some 680 ohm resistors. Would these be OK or would having a slightly lower value (1 - 10 ohms) be OK? This is the schematic I'm going by. Thanks to whoever made it. Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted March 26, 2022 Share Posted March 26, 2022 Those are some pretty forgiving circuits, you can go up or down at least 20-30 Ohm (580 will probably still work). Or just use a trimmer, if it's a one off. 2 Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted March 28, 2022 Share Posted March 28, 2022 On 3/26/2022 at 3:18 PM, CMR said: How essential is it that these need to be 620 ohms? Can they be a little over? It looks like they're just holding pins 5 and 9 high until the switches pull them low If you look closely you will see that they are connected to pin 8 (GND) and so would not be holding Pins 5 & 9 High. Are you certain that schematic is correct as I am not entirely sure what their purpose would be, I can only think they are providing some kind of noise immunity on the paddle inputs instead of them being left floating. EDIT: Remainder of post removed as I looking at things incorrectly. Quote Link to comment Share on other sites More sharing options...
+Pat Brady Posted March 28, 2022 Share Posted March 28, 2022 14 hours ago, Stephen Moss said: If you look closely you will see that they are connected to pin 8 (GND) and so would not be holding Pins 5 & 9 High. Are you certain that schematic is correct as I am not entirely sure what their purpose would be, I can only think they are providing some kind of noise immunity on the paddle inputs instead of them being left floating. In 7800 2-button mode, the console drives pin 6 high and these resistors pull pins 5 and 9 down unless the corresponding button is pressed. 1 Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted March 30, 2022 Share Posted March 30, 2022 On 3/29/2022 at 12:20 AM, Pat Brady said: In 7800 2-button mode, the console drives pin 6 high and these resistors pull pins 5 and 9 down unless the corresponding button is pressed. My bad, my brain was operating on the inputs being active low when writing my previous reply as active low that is the Atari "Standard" for controller button inputs. As Pin 6 is being driven high it therefore does not really matter too much what the resistor value is (within reason) so with regard to the original question moving up or down to the next preferred value should be fine, although generally up would be better as it uses less current. 1 Quote Link to comment Share on other sites More sharing options...
CMR Posted March 31, 2022 Author Share Posted March 31, 2022 Thanks for the info. I'm always getting pull-up and pull-down resistors confused myself. 1 Quote Link to comment Share on other sites More sharing options...
+karri Posted April 17, 2022 Share Posted April 17, 2022 I just finished modding a Competition Pro joystick by rotating the switches by 90 degrees so I get the buttons to the right side. By using 10000 , 2200 and 1000 ohms in parallell I got 643 ohms that worked on my PAL unit. 1 Quote Link to comment Share on other sites More sharing options...
CMR Posted April 19, 2022 Author Share Posted April 19, 2022 I went with the 680ohm. It seems to work fine also. Quote Link to comment Share on other sites More sharing options...
Lynxpro Posted April 20, 2022 Share Posted April 20, 2022 On 4/17/2022 at 1:39 AM, karri said: I just finished modding a Competition Pro joystick by rotating the switches by 90 degrees so I get the buttons to the right side. By using 10000 , 2200 and 1000 ohms in parallell I got 643 ohms that worked on my PAL unit. I've seen that done with the 5200 version of the Competition Pro so the buttons are all on the left. Worked great when I played with it. Quote Link to comment Share on other sites More sharing options...
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