Automated Fixtures Mac 2K Profile II !FbET!Help!


Hey guys could really use another set of brains on this one. I'm working on a Mac 2K Profile II. I keep getting the Feedback Error Tilt (FbET). I've replaced the PCB and traced all feedback sensor lines. Everything is intact. The shipping locks are off. Really scratching my head at this point. The tilt motor doesn't move at all. However, when I cross plugged the tilt and pan on the PCB I did get a response from the tilt motor. Any assistance would be appreciated.
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Well-Known Member
If the motor's not moving then your problem isn't in the feedback system. If the head isn't tilting there's nothing to trip the sensor.

Since you've got a motor that's not working when connected properly, but you get it to work by swapping cables around, keep working towards the motherboard from the PCB you're talking about. Pretty much everything on a Mac works on a home run from the motherboard and all of the other PCB's in the head and yoke just relay that information from one cable to another. So you just have to work back. If you have a few extra known good cables lying around you can use them to run from PCB to PCB to see if the old cable had a short. The cables in Macs are such a small gauge that they short for all kinds of silly reasons and are the most common issue I've found in teching Macs.

If you're reasonably sure that all the PCB's and cables are good then you can open the base of the unit and make you're own home run from the mother board. Just unplug the Pan motors so that the head doesn't spin on you (They are usually labeled PAN but could also be labeled 33) then you can run whatever cable you can find that's long enough straight out of the motorboard to the tilt motor. Just like with pan usually the cables for the tilt motors are labeled TILT but they could also be labeled 32. Pay attention to the order of the color scheme of the motor cables because the left motor cable is backwards from the right one.

If you come to find out that the problem is that the motherboard try flashing the software on it. If that doesn't work you probably need to call Light Parts or your favorite other repair house......
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Active Member
Good Morning

It sounds like you swapped the pan & tilt at the main PCB. If that’s what you did & the problem moved then the problem is on the board.
I'd look at the driver chip; they should be in DIP sockets, take note where pin 1 is.
Sorry, I just reread, you swapped the PCB & the problem remained. How odd...
OK.. Have you tried unplugging 1 of the motors at a time?
What do you mean "The tilt motor doesn't move at all." Is it with or without power? If it has power, that may not be a bad thing. If it was without power &it was a HES fixture ,I'd say it's a bad motor. Martin fixtures don't typically do that.

Its late & my brain is starting to hurt. I'll sleep on it & try again in the morning.

Good Luck


Active Member
There's two tilt motors. Try unplugging one and see if the fixture will then move. We had an issue recently where one of the two motors was a half step off from the other causing the two to fight against themselves. It was a pretty frustrating day, along with the HTER from the plug having two available sockets, only one of which works.

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