First off, it helps to understand how the cutter works.
When you turn on the cutter, the first thing the cutter does is it moves to the right and watches the optic sensor for the right side notch in the rail. It will do this to determine home. Once it reads this it knows were absolute 0 is on the right. Older firmware will constantly monitor the optic sensors for the left optic window during operation. If it sees it it will stop movement to the left. Newer firmware requires the width of the cutter be learned (see info at bottom). This only happens once. This width is stored in the motherboard. When the cutter finds the left optic window it calculates maximum width given the length that it has stored. So any new motherboard with newer firmware will need to have the cutter width learned once.
So if the carriage moves to the right and hits the right side wall this means the motherboard is not seeing the right optic sensor trip when it passes the notch in the rail. This behavior can be caused by one of the following:
1) Bad optic sensor or bad carriage position sensor PCB (the little PCB on top of the carriage) – This is a rare occurrence.
2) The cable from the motherboard to the carriage is bad or has a cracked wire. – This is common due to the cable flexing for the life of the cutter.
3) The motherboard is bad and not reading the sensor properly.
4) One of the servo motors is bad or the wire from the motherboard to the servo motor is bad. (Change servo motor) Although the carriage motor would be the likely suspect, we have also seen the roller bar motor cause similar behavior.
I would like to note that if a cutter has recently been repaired with a new motherboard that it is possible that the carriage cable may have been installed backwards when connected to either the motherboard connector or the carriage position sensor connector. The flat ribbon cable is not keyed and it is easy for it to be installed 180° in the connector sockets. Same thing with the USB connector cable. It is also a flat ribbon cable that is not keyed.
So if a cutter is working OK and this issue has just occurred then I would recommend changing the carriage cable to see if it resolves the issue. If you were troubleshooting the cutter and then this issue started it may be that the carriage cable is rotated in one of the connectors. Please check this anytime you have replaced a motherboard or disconnected and reconnected these flat white ribbon cables.
Learning cutter width for newer firmware:
Newer cutter motherboards from Saga need to read the cutter width when they are first installed. The optic sensor will move left and then right to find the ends of travel of the cutter. This information is stored in the motherboard so the cutter width only needs to be read once.
1) Make sure the carriage in not up against one of the ends of the travel. Anywhere in the center of the cutter is fine to start.
2) Turn on the cutter
3) Press set + test + Enter (all at the same time)
4) Release all 3 buttons
5) Wait for cutter to read width
6) Turn cutter off and on.