Product

Trendsetter VLF AL

Component

MCU

Symptoms

When the cassette is pulled all the way out for loading, Print Console reports a door open error. The error may go away by itself or after shaking the chariot.

Cause

Chariot safety switch adjustment or faulty switch.
The two Omron switches inside the bottom left of the MCU are part of the safety loop. When the optical sensor in the bottom right detects that the chariot is all the way out, the status of the two Omron switches is checked. Both switches have to be closed or else the door open error will be reported. The switches have lever arms with rollers and they roll on the bottom chariot rail as the chariot is pulled out. When the chariot is all the way out, both rollers should drop into indentations in the chariot rail, which closes the switches. Due to mechanical tolerances, it is possible that one of the switches is fully inside the indentation while the other one is on the edge of the indentation. If one or both of the switches is still open when the cassette is all the way out, the door safety loop fault will be reported.

Solution

Adjust the switches so that they will both actuate at the same time. There is very little play in the switch bracket. Loosen the four small screws that hold the Omron switch to the bracket and twist the switch. This will move the roller on the switch actuator arm forward and backwards a few millimeters, which is enough to make them trip at the same time.
NOTE: Do not loosen the four larger screws on the top of the bracket. This adjustment sets the spring tension on the switch so that it actuates when the roller falls into the indentation. If you change this tension, it will take several adjustment iterations to get the switch to trip reliably again. This can also cause the door loop problem so you may have to do this. Check the other adjustment first.

Technical contact(s)

Al Edge

Submitted by

Al Edge

Date submitted

24 Jun 2004