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Mac 250 Krypton Spares


posty07

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Hi,

I've have just got hold of a couple mac 250 kryptons but they're both needing new tilt belts, however the ones I can find are all over £10 each so am wondering if anyone might have some spares lying around that I could buy?

 

Also, they're quite loud when moving in either direction, it seems to be a vibration when the steppers are turning, could this be the bearings in the motors or the bearings on the head?

 

I've had one apart and it seems that the main bearings are ok, but that's without any weight on them

 

Any help would be appreciated,

Thanks!

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Also, they're quite loud when moving in either direction, it seems to be a vibration when the steppers are turning, could this be the bearings in the motors or the bearings on the head?

No. Its more likely that there's a fault with the stepper motor driver circuit. What happens is that the driver chip can't regulate the current, and therefore the torque, of one or both sets of coils in the motor. This leads to the noise you're describing. This is quite common with older Martin fixtures, at least it is with the ones I've fixed. Fixing the fault requires new resistors being soldered on to the motherboard

 

Or it might be a lose body panel that amplifies the noise that is always present when old Macs waggle their heads....

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Fair enough David ;) just thought it seemed pricey for a piece of rubber

 

And thanks for your help gyro, is there any chance you know which resisitors? And if you could get a picture maybe?

 

Thanks,

Adam

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I guess yeah, they're only thin ones so that's probably got something to do with it. Though I've found generic timing belts cheaper now anyway, I can get them for just £5 each from a robotics company :-D
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For the sake of $7 (5 quid) just get the proper Martin part.

 

As its just annoying to replace the belts (Well I mean it's no easy task). And you would be quite annoyed if you foudn that your cheaper belt snapped after only half a dozen uses.

 

Do you know if these other belts have the same size and spacing of the teeth? Do you know if they are strong enough to handle the amount of torque and not snap?

 

For someone that owns Kryptons, you seem awfully concerned about $15 (10quid)

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Well very true, I've only just bought them and they were meant to be in useable condition so was hoping to not spend anything repairing them, I guess that's probably the reason I'm concerned about spending more money :')

 

But you're right, now that I've bought these ones I'll try them but if they do fail I'll go proper Martin ones.. I was in hope that they were probably going to be ok as they're from a robotics company

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As its just annoying to replace the belts (Well I mean it's no easy task). And you would be quite annoyed if you foudn that your cheaper belt snapped after only half a dozen uses.

 

Do you know if these other belts have the same size and spacing of the teeth? Do you know if they are strong enough to handle the amount of torque and not snap?

Oh for goodness sake! This sounds like the old arguments about the 'special' Martin oil that you had to use on your lights, despite the fact that it cost considerably more than normal silicone oil and yet was exactly the same stuff. Do you think that Martin have their own dedicated belt manufacturing plant? Of course not. They buy in their belts from the same companies that everyone else does. Also, it's often a lot easier to source components from an engineering company than a moving light company.

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Good point Gyro, well said! :') Oh yeah I'm not sure about the extra noise being caused by the driver circuit as it's doing it when they're off too, its not as bad on tilt and its only on one light but it's sounding like there's something up with the motor.. could it be time for a new one? They were ex-hire ones and have done 9000 hrs...

 

Adam

 

 

 

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Oh yeah I'm not sure about the extra noise being caused by the driver circuit as it's doing it when they're off too

With the power off, disconnect the cables to the pan and tilt motors. If it still makes a noise with the motors disconnected then its a mechanical fault. But if they stop making a noise, then its an electrical fault. Sounds weird, I know, but driver circuit problems can still affect the motors even when the light is switched off.

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