color change stepper index error / heads down

[Rod or Sharon]

Sue,

The "tweener" version of the Amaya is an XT and is what they refer to as a "pre-XT. It is still red and white. These pre-XT's do not have the optical sensors we described earlier that control Home and Color index functions.

Glad it was nothing real serious.....

Rod Springer
Amaya Tech & Trainer

[zenman]

Those optical sensors are more of a optical switch. I just replaced these on my Big Red during a similar situation. They sell them at Mouser online if you want to save a few bucks. I bought extras. If you look on the back of the needle case you can see black plastic fingers, more like a solid plastic ledge with strips cut out. I would say that there is an eight of an inch of space between the fingers. The "optical sensor" allows the black plastic fingers to go in between the top and the bottom of the sensor. the top of the sensor shines a very small light (like a flashlight) and the bottom senses it and tells the Amaya computer if it sees the light. When it sees a light, it is at a needle position.

There are two of the optical sensors, on in the middle back of the needle case and one on the right as you are looking at it.

The middle one finds the #8 needle. It does this because there is a separate gap in another piece of plastic on the back of the needle case that this one finds using the light method.

The one on the right finds the current needle position using the fingers mentioned earlier.

When the machine boots up the needle case tries to find the #8 needle using the "home" sensor. if it can't find it, the machine freaks out and gives a "home" error.

After it find the home position, the machine goes to the needle it was last at. If the right sensor is malfunctioning the needle case goes way past needle #1 and you hear the motor struggling and then gives up. There is a timer for the Amaya computer between colors.

The sensor is black and small. It has a very think piece of plastic holding the top and the bottom together like a sandwich. The space between the top and the bottom and just a little wider than the thickness of the plastic fingers.

If dust or oil gets into between the top and the bottom of the sensor the machine had not idea where home is or a needle position. Sometimes the needle case gets jostled and the plastic finger, when it is inside of the sensor, rises up and bends the sensor and the sensor light does not point and the light detector or even break the thin support of the top and bottom.


To replace these requires removing the needle case. Doing that has a lot of excitement the first time.

It is a krappy design that melco changed. It is a cheap answer to the linear strip used on ink jet printers. But not they use more expensive encoder on the color change motor itself.