Nicktaylor Posted August 15, 2012 Share Posted August 15, 2012 I know the micro switch should close a circuit which makes the yoke change direction, but for some reason one of mine has an intermittent fault and it tries to keep rotating clockwise. All others are rigged so I can compare to see if something is missing. Later I will put a meter on the switch but does anyone have an idea where next to look? Thanks Link to comment Share on other sites More sharing options...
stuart.thompson Posted August 15, 2012 Share Posted August 15, 2012 on the old mac 250s the whole pan stop bracket can slip down so the lolly pop will pass over the switch and not activate it - have a look at that and see if it needs moving upwards if the switch seems to meter out ok. Link to comment Share on other sites More sharing options...
Nicktaylor Posted August 15, 2012 Author Share Posted August 15, 2012 Switch meters fine. Sometimes it work perfectly, then suddenly it decides not to bounce off the stop. Looking at it when it works perfectly, the second click on the switch seems to be the signal for the motor to reverse direction? Maybe there is an issue with the stepper driver chip?On the large drive gear on the yoke there is the large grub screw that presses on the micro switch and the spring tab. I also note there is smaller threaded hole almost opposite on the large gear. With mine that is empty. As I said before all my others are rigged so I have not got one to hand for comparison. is there screw missing ? Link to comment Share on other sites More sharing options...
stuart.thompson Posted August 15, 2012 Share Posted August 15, 2012 as long as the pan is moving smoothly there isn't an issue with the motor driver chip... If the switch meters out fine then I would say it is the switch is alligned too low and needs the bracket with the switch on moving upwards (common problem with MAC 250's) or you have a problem with the wire set from the switch back to the PCB. Link to comment Share on other sites More sharing options...
Nicktaylor Posted August 15, 2012 Author Share Posted August 15, 2012 as long as the pan is moving smoothly there isn't an issue with the motor driver chip... If the switch meters out fine then I would say it is the switch is alligned too low and needs the bracket with the switch on moving upwards (common problem with MAC 250's) or you have a problem with the wire set from the switch back to the PCB. Well I have spent some time with this unit. I think the microswitch lever was a bit bent so the yoke was having to move too far clock wise to make the return happen. Having said that once in about six times powering up it suddenly does not work. Switching off and manually moving yoke to the end of its movements then makes it work again. I guess I will have to wait for another working one to be set up next door to this one to see if there is anything else different! Link to comment Share on other sites More sharing options...
DrV Posted August 18, 2012 Share Posted August 18, 2012 as long as the pan is moving smoothly there isn't an issue with the motor driver chip... If the switch meters out fine then I would say it is the switch is alligned too low and needs the bracket with the switch on moving upwards (common problem with MAC 250's) or you have a problem with the wire set from the switch back to the PCB. Well I have spent some time with this unit. I think the microswitch lever was a bit bent so the yoke was having to move too far clock wise to make the return happen. Having said that once in about six times powering up it suddenly does not work. Switching off and manually moving yoke to the end of its movements then makes it work again. I guess I will have to wait for another working one to be set up next door to this one to see if there is anything else different!As Stuart says, that sounds like a problem with the wireset then. On a 250, the controller is moving around in the side arm and the microswitch is fixed to the base, so there is a wire going up through the central bearing and into the controller. I suggest you connect your meter to the switch end, short out the other end, at the controller, (so that you see a nice solid zero ohms on the meter) and then swing the head around to see whether it goes high resistance at some point. Dave Link to comment Share on other sites More sharing options...
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