Atari 2600 4 switch, Down not working on controller?

[Mr. Postman]

Bridging the IN from the C-parts to ground: up, left and right work but not down. If it's not making it to the in must be the DB-9. Very odd that it tests ok. Thx, lots of love. I'll swap the p2 DB-9 over to P1 just to test.

Edited June 2, 2017 by Mr. Postman

[Mr. Postman]

It there anyplace i can check with a wire to make it work? Riot to gnd?

[SignGuy81]

Okay. I'm back. Now, the schematic I'm looking at doesn't show caps on the direction lines but then realized they showed it on pin 1 so I figure they didn't include it on the others for room on the schematic. Found another that showed it them on the directional inputs.

 

Sorry about that but the schematic didn't show anything connected between pin 2 and the RIOT. Now knowing that you jumped from ground, and pin 2 and still nothing, swap the CAP with a .001uF cap and it will probably solve the issue.

 

EDIT:

And if what's is face comes back yeah I was wrong, but not about what you said I was wrong about, lol they are caps.

Edited June 2, 2017 by SignGuy81

[Mr. Postman]

Thx a ton, this is a Rev 5 pal console so it's probably different. Thanks a ton, I've learned a lot. I'll swap the up cap with the down real quick to verify.

[SignGuy81]

Thx a ton, this is a Rev 5 pal console so it's probably different. Thanks a ton, I've learned a lot. I'll swap the up cap with the down real quick to verify.

 

Don't thank me you were actually on the right path to start with, it just threw me off when you said it was a resistor to start off with so I didn't even entertain the idea because my schematic didn't show caps on the direction lines(other than pin 1 which I didn't even notice because I had it scrolled just seeing line from pin 2 which showed nothing along with 3 and 4 going straight to the RIOT chip.

Edited June 2, 2017 by SignGuy81

[SignGuy81]

You can actually probably just remove the cap to test it but still need one on there for debounce but you should be able to see it work without the cap in there. I went back and looked you said 0 and not OL like I originally thought so yeah the cap was shorted to ground making the input stay grounded all the time.

Edited June 2, 2017 by SignGuy81

[Mr. Postman]

I removed the cap for down and tossed it. I removed the cap from left and put it in down.

 

Everything works, no cap in the left (C229).

 

So I should add a cap to this? Just be happy it works?

 

 

Thanks for everything!

[Mr. Postman]

What's your final verdict, SignGuy? Thanks for the help

 

100% functional now, but I am now completely missing the cap from the left input even though left still works.

Edited June 2, 2017 by Mr. Postman

[Mr. Postman]

I appreciate all the help, I guess I'll leave it as-is now. Thank you.

[SignGuy81]

Just whenever you can add a cap to replace it. Certain things this could be an issue. For example if you are scrolling on something up and down that has numbers going down may skip numbers because the input isn't being debounced.

[+DrVenkman]

The OP's problem is solved so this is just to clarify what seems to be some misinformation along the way...

 

At what point did I act like a know it all? You're the one acting like a jackass in a thread where someone asked for help. If the DB9 tests fine and the RIOT tests fine (wouldn't a bad RIOT produce funky video or have problems other than 1 direction?) and there's only one component between them.....

 

The 6532 chip does several things: RAM Input/Output Timer (RIOT) - it provides 128 bytes (that's it, BYTES, not kilobytes) for data storage, processes basically all the system inputs except trigger lines and has timing functions. Any part of this chip can fail and the results may or may not be immediately visible. For instance, in the last couple years I've bought two 4-switch units that both had bad RIOT chips when I got them. The only system that manifested itself was that the system difficulty switches weren't working. Rather, the switches and traces were fine, but moving them wasn't being registered. In one case, the effect was only for Player 2 so it was only easily noticeable in 2 player games such as Space Invaders, when setting difficulty A doubles the width of the player's gun. In the other it was the player 1 difficulty switch so it was easy to observe the problem and, having seen it before, diagnose it.

 

In neither case did the failed RIOT give otherwise-noticeable problems in game play, corrupted images from bad RAM, or anything else. Just difficulty switch reading.

 

tl;dr:

 

No. RIOT chips can fail in ways that don't obviously manifest themselves in funky video.

[Mr. Postman]

I totally thank everyone for the help, I'm very happy to have the assistance of such fine folks.

[TheTIGuy]

To be clear, the beige colour capsules ARE resistors, and you can see on the bottom right there are diodes and caps also with a CXXX No. labeling. This may or may not be what SignGuy was talking about, so PLEASE stop bickering!

[SignGuy81]

To be clear, the beige colour capsules ARE resistors, and you can see on the bottom right there are diodes and caps also with a CXXX No. labeling. This may or may not be what SignGuy was talking about, so PLEASE stop bickering!

 

 

Just to be CLEARER(AND CORRECT), those labeled C227-C230(green, not beige) are capacitors, and believe it or not C236 is not a diode, it is a capacitor(0.01uF). And the bickering has been stopped over a month ago.

 

 

 

 

 

You can look up the locations as well in the FSM for the 2600 and see the symbols used for yourself, all the ones I said were caps are caps, not resistors, not diodes, they are caps.

Edited July 18, 2017 by SignGuy81

[+-^CrossBow^-]

I've often wondered if Atari did this on purpose to confuse back in the day trying to make it more difficult for it be cloned and pirated? After all, if you didn't have the schemes and measure them properly, you would naturally think those were resistors, especially with a crappy snapshot of the board to go by?