Crane 780 Fault "HOME.SNS 03"

[Aaron]

Hi,

I have a Crane 780 vending machine which has developed a fault after removing, cleaning and replacing the F tray. This causes the machine to go out of service. It has previously had intermittent faults where certain selections would report "make another selection" until the tray harnesses were disconnected and reconnected. The diagnostic code is "HOME.SNS 03" which the manual says means "an error in both odd and even home lines". There is a wiring harness (HARNESS MAIN CONTROL TO SENSOR Part Number: 1679012) which connects to a circuit board on each row from A through to F. Each tray harness plugs into each of these circuit boards.

When I disconnect the main control sensor harness from the row F circuit board the fault clears and is replaced with the error "ERR F" (error in row f) which I would expect as it has been disconnected. The vending machine will then go back into service vending from rows A to E. Whenever I plug the main control sensor harness back into the row F circuit the "HOME.SNS 03" error reappears taking the machine back out of service. This is without even trying to plug the row F tray back into the circuit.

This error would seem to indicate that there is a fault with the harness, maybe shorting/disconnected wire somewhere on the F circuit connector? Does this sound right? If so where would I be able to source part 1679012 from?

Thanks,

Aaron. 

[cvending]

I am not sure what the sensor harness is but if you're talking about the motor trailer harness motor harness that connects to the side of the trade board is that could be bad or the trade board itself is bad

[falls]

18 hours ago, Aaron said:

This error would seem to indicate that there is a fault with the harness, maybe shorting/disconnected wire somewhere on the F circuit connector? Does this sound right? If so where would I be able to source part 1679012 from?

It doesn't sound right to me, I think the fact that the fault does not persist when the harness is removed from the circuit board indicates the fault to be in the pcb or it's headers. Check the board for poor solder connections, and check that the header pins are all aligned, not touching, and don't have any foreign matter bridging the pins. I think the pcb is just a connector between the 2 harnesses, and has no active electronics (but I've been wrong before).  

[Aaron]

Thanks for the diagram Falls. You're right, I was talking about the harness that plugs into the connector on the left of your diagram. The Tray harness and the motors on the F tray work successfully when plugged into the E tray PCB. Has to be either the PCB or control board to sensor harness. I've checked the pcb on the F tray (pics attached) but I can't see any obvious faults. I'll see if I can find a supplier for both parts.