Toy Taxi crane goes to far right

[msadan]

I have an intermittent problem with a Toy Taxi crane.  Occasionally it acts like the joystick is being held in the right position, and the carriage moves to the far right side of the cabinet and stays there.  You can override this with the joystick - it will move to the left / back front, but if you release the joystick it goes all the way to the right.  Disconnecting the wires from the right joystick switch doesn't change anything so I assume that it's not a joystick switch problem.  There are no obvious chafed wires.  Generally if the game has been turned off for a few minutes then turned back on it operates normally.  That's about as far as I've gotten with troubleshooting.  I'm more of a pinball guy so I'm not sure what to check next.  Any suggestions would be appreciated.  Thanks!!

  

[gumball guy]

First I would double check all connections and wires on the gantry (especially the connection to the left/right motor. I know you checked one side of the joystick switches but I will throw this in.... I would put all of the joystick switches on a meter just to make positively sure they are all working correctly. Remember, on the joystick, when you are moving the joystick to the right it is usually depressing the switch to the left side of the joystick. I have had people spill drinks on the control box that make the switches sticky and I have had them just slam it so hard that it actually cracks/breaks the joystick housing underneath which would lead to issues like what you describe.  If the joystick/switches are good I would look at electrical. The fact that it stops malfunctioning when it's off for a few minutes would make me suspect a possible short in the power supply. Once the power supply heats up, the problems start, then when you turn it off it has a few minutes to cool down and works again for a while. If you have an extra power supply that you know is good, you could switch it out and see if it stops happening. Once you have cleared the power supply as the culprit look at the gantry right/left motor. I have had a gantry motor fail in the manner you describe but most of the time the failure is not intermittent. Of course it could be the board as well but, like the motors, when the board goes bad, the issues it causes are usually not intermittent....it just stops working correctly. Most of these Chinese cranes don't have a limiting switch on the right side so that can be ruled out. Make sure your wiring harness connection and contacts are solid. Look at your claw coil and make sure there isn't any evidence of exposed/burnt wires. It could be a lose or broken wire but again, if turning it off for a few minutes seems to cure the problem for a while I really think it is a short or a board problem. I wish I had a silver bullet for you but unfortunately troubleshooting is often trial and error. Please let us know what the culprit was when you figure it out.

[msadan]

Thanks for the help!  I had some time to try to troubleshoot it today, but of course it worked perfectly all day long .  I think I can rule out the joystick switches and related wiring, because when it is having this issue if I cycle the power the carriage immediately moves to the right at power up, even before the start button has been hit.  When it's NOT acting up if I cycle the power while holding the joystick to the right it has no effect on the carriage movement.  I'm definitely leaning towards it being a board or power supply issue.

I was able to determine the function of all of the relays, so next time it acts up I'll be able to check and see if any relays are in the wrong position.  There's one relay that looks like it could cause this problem if it gets stuck in the activated position.

So, I'm making progress.  When / if I figure it out I'll post the answer here.