Uzebox JAMMA

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L4rry
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Re: Uzebox JAMMA

Post by L4rry » Wed Feb 07, 2018 5:18 pm

Jubatian wrote:
Wed Feb 07, 2018 5:03 pm
If you see that some buttons are permanently active, maybe you could check the voltage at the JAMMA socket to determine whether it is something in the cabinet or something might be wrong with the Uzebox JAMMA. On the JAMMA board there are four 4021N shift register ICs, check their pinout, and try to measure the voltage on the input pins. The problem should be somewhere around there, if your controllers mostly work, then likely these shift register ICs communicate all right with the ATMega, just they are not getting the proper input levels.
Thank you. That gives me some direction. It's good for me to do some hardware debugging. My experience is way too limited.

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L4rry
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Re: Uzebox JAMMA

Post by L4rry » Sat Feb 10, 2018 3:28 pm

Jubatian wrote:
Wed Feb 07, 2018 5:03 pm
If you see that some buttons are permanently active, maybe you could check the voltage at the JAMMA socket to determine whether it is something in the cabinet or something might be wrong with the Uzebox JAMMA. On the JAMMA board there are four 4021N shift register ICs, check their pinout, and try to measure the voltage on the input pins. The problem should be somewhere around there, if your controllers mostly work, then likely these shift register ICs communicate all right with the ATMega, just they are not getting the proper input levels.
So I hacked sofswitch to boot directly into the control input test screen, flashed it on my Uzebox JAMMA and made some measurements with my multi-meter.
  • All shift registers have a constant 5V input on the top left pin
  • I get a constant 12V input on IC3 and IC2
  • I get 5V output from IC3
  • I get 5V output from IC2 instead of 3.3V... I bought the wrong voltage regulator :oops: I'm assuming this affects the SD card interface. What else would this affect?
  • The 5V and 12V pins on the JAMMA interface read correctly (part side)
  • Pins 16, 22 and 23 ( P1 COIN, P1 PUSH 1 and P1 PUSH 2) on the JAMMA interface are on a constant 5V (part side, no buttons pressed). They also happen to be the only three buttons that function correctly according to Softswitch (for either P1 or P2)
  • All other control input pins (17-21, 24) have no voltage (part side, no buttons pressed)
Apart from my obvious screw up with the voltage regulator, anything else I can check or something you can see from the above that looks irregular?

Here's the JAMMA PIN diagram I used for reference:
jamma_standard.png
jamma_standard.png (129.64 KiB) Viewed 2212 times

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Jubatian
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Re: Uzebox JAMMA

Post by Jubatian » Sat Feb 10, 2018 5:12 pm

L4rry wrote:
Sat Feb 10, 2018 3:28 pm
  • All other control input pins (17-21, 24) have no voltage (part side, no buttons pressed)
This seems to be wrong for me. I found that the buttons should be driving these pins to ground, so normally you should see +5V there. Check IC5's inputs, this should be receiving most of Player 1's inputs, maybe the soldering of RN1 is not perfect so it fails to pull these lines to +5V (VCC).

I can't believe I am debugging hardware here :P (I really should get some soldering tools & crap and start doing it myself :D )

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L4rry
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Re: Uzebox JAMMA

Post by L4rry » Sat Feb 10, 2018 6:27 pm

Jubatian wrote:
Sat Feb 10, 2018 5:12 pm
I can't believe I am debugging hardware here :P (I really should get some soldering tools & crap and start doing it myself :D )
Haha! I feel the same :) I am enjoying it immensely though. Even though my hardware expertise is only slightly above non-existent, the trial & error and the bits and pieces I pick up around here and online elsewhere is making me a bit more knowledgeable day by day. I need to not waste money on incorrect components though. That's just an own goal.

Thanks for the tips. I really do appreciate the feedback and sounding board.

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