Robotron mini coins up but won't play...

pookdolie

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I can put the machine into test mode. I can bring up the Options menu.

Left stick does nothing. Left to right on the right stick moves the Options "arrow" up and down. Can't change values.

Go into attract mode, seems fine. Machine coins up with good sound. But 1P and 2P buttons do nothing.

Checked the CP last night and made sure I had a good ground, good connections. Nothing looks wrong.

Took batteries off the board. No change.

Anyone ever have a similar Robotron issue? What should I look at next? PCB, or CP?
 
I can put the machine into test mode. I can bring up the Options menu.

Left stick does nothing. Left to right on the right stick moves the Options "arrow" up and down. Can't change values.

Go into attract mode, seems fine. Machine coins up with good sound. But 1P and 2P buttons do nothing.

Checked the CP last night and made sure I had a good ground, good connections. Nothing looks wrong.

Took batteries off the board. No change.

Anyone ever have a similar Robotron issue? What should I look at next? PCB, or CP?

Run through the switches test. See what buttons are don't what and go from there. My Robotron had an issue where it wouldn't read a couple of directions and showed one of the coin switches as always active. I ended up having a bad IC on the board.

Double check all wiring too to make sure that everything is hooked up right.
 
Run through the switches test. See what buttons are don't what and go from there. My Robotron had an issue where it wouldn't read a couple of directions and showed one of the coin switches as always active. I ended up having a bad IC on the board.

So, I did get a chance to play around with this last night. My "advance", "reset high scores" and the "auto-manual" buttons registered on the switches test. But I don't think anything else would. However, the right Fire joystick did move around the arrow in the options menu. (Which I don't think is right - I think the Fire stick is supposed to change the values). So I at least know that stick is being registered somehow, which means my CP isn't totally dead.

Are the ICs socketed chips? If so, maybe I can try re-seating them...
 
So, I did get a chance to play around with this last night. My "advance", "reset high scores" and the "auto-manual" buttons registered on the switches test. But I don't think anything else would. However, the right Fire joystick did move around the arrow in the options menu. (Which I don't think is right - I think the Fire stick is supposed to change the values). So I at least know that stick is being registered somehow, which means my CP isn't totally dead.

Are the ICs socketed chips? If so, maybe I can try re-seating them...

Nope... wasn't socketed. Needed a logic probe and an extra set of hands to test the thing too.

I just looked at my schematics and the only thing I see that all of those controls have in common (P1 and P2 inputs) is IC2 and the ribbon cable on your interface board. IC2 is a 6821 PIA according to the schematics... unlikely that would go bad... so I'd have to start blaming the ribbon cable. Make sure it's seating good and try fooling with it while you're in the switch test and holding a (previously) dead direction... see if you get any love from it.

EDIT: Just noticed you said mini, not cocktail. So... guess it COULD be IC's 3, 4 or 6 as well.
 
Nope... wasn't socketed. Needed a logic probe and an extra set of hands to test the thing too.

I just looked at my schematics and the only thing I see that all of those controls have in common (P1 and P2 inputs) is IC2 and the ribbon cable on your interface board. IC2 is a 6821 PIA according to the schematics... unlikely that would go bad... so I'd have to start blaming the ribbon cable. Make sure it's seating good and try fooling with it while you're in the switch test and holding a (previously) dead direction... see if you get any love from it.

EDIT: Just noticed you said mini, not cocktail. So... guess it COULD be IC's 3, 4 or 6 as well.

Awesome. I shall try this once I get back to the machine and let you know what happens...
 
Quite often if it is just a few switches it is a ground wire issue. Make sure you get a good connection to ground. Use a meter to verify continuity.

If it not the ground, then check the I/O card with a jumper cable. Put it into switch test and then ground one end of the jumper (I use pin 10 on 3J3, the pin closest to the ribbon cable). Then just touch the other end of the jumper cable to each pin in turn.

For Robotron, the pins are:
10 - ground
9 - fire right
8 - fire down
7 - fire up
6 - 2 Player Start
5 - 1 Player Start
4 - move right
3 - move left
2 - move down
1 - move up
10 - ground
9 - (fire left 2)
8 - (fire down 2)
7 - (fire up 2)
6 - (fire right 2)
5 - (move right 2)
4 - (move left 2)
3 - (move down 2)
2 - (move up 2)
1 - fire left

If you don't see those messages, then check the corresponding 74LS257 chip and the 4049 chips to make sure the signals are getting through.

ken
 
Messed around with the interface board ribbon cable. After re-seating it and bending it a few times, everything is working again. Thx guys!
 
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