A Mac 300 nightmare.

[Simon Brockwell]

Have numerous problems with 2 of my Mac 300s. Have been servicing moving lights for a few year, particuarly Mac 2ks. Think I have found out why Mac 300s were discontinued by Martin - they are unserviceable! After inheriting an installed rig I opened up a few fixtures to clean them and they pretty mcuh fell apart from heat damage and lack of cleaning. Ive done my best but they are a proper nighmare to work on. Any suggestions on the following problems would be greatly appriciated as Martin never made a service manual for this fixture.

 

1) FbET - Tilt motor engages on power up and resets ok. Hits the microswitch and homes fine. When it has homed the motor is still engaged but seems incapable of holding the head upright and it doesnt try to right itself if you move it, but the stepper does provide resistance. Both motor loom and sensor loom bleep out fine. I suspect its a duff motor but could also be the drive output from the main PCB. I am aware of the drive tester for stepper motors but I dont have one. Anyone know how to make one?

 

2) ShER - Short error on lamp circuit. Does not effect lamp on or lamp off and apparently it has had this error for months with no ill effects, but in an effort to cure it replaced the relay which hasnt really work so I guess thats not the problem. There is some insualtion missing which normally covers the screw head holding in the high voltage line into the ignitor, which looks potentially dangerous but I doubt it the problem and I wouldnt mind not buying a whole new ignitor. Anyone else experienced this?

 

3) CoER - Color Error. Drive to motor is fine, this is an indexing problem. Ive tested the sensor and magnet, thats all fine as is current up the loom, which is why im a little stumped.

 

4) CMY flag/wheels - How the hell do you replace these things without smashing them? The ones ive replaced were broken so with a bit of brute force I managed to remove them, but like the new cyan and magenta flags arent sitting right so I need to remove them intact but they wont budge. Ive tried everything but cant afford to damage the dichroics. There must be a way, any ideas?

 

5) Looms - As you will know a lot of the looms inside Macs get damaged by the way they are industrially zip tied to the chasis. In this case my display loom is duff and needs replacing, but as the PCB is housed in the arm and the display is in the base ive had to completley remove the yoke to gain access but still cant get into the base enough to replace it. Is there an easy way to do this?

 

Any ideas would be gratefully received as at the moment these units are in many pieces on my work bench and I can only devote so much time to maintaining them - not to mention the implicated costs. Tar very much.

 

Brock

[Brian]

Anyone know how to make one?

 

To test drivers you could use a spare motor but for at it's simplest you can use 4 LEDs.

 

If you look at how steppers work (Wikipedia?) you'll see that the most common configuration is to have 4 windings all with one end fed power and the other ends pulled to ground in a specific sequence. If you make a little test rig with 4 LEDs plus their series current limiting resistors you can observe the sequence as you change to pan/tilt position. If you switch down to 8-bit resolution it's much easier to see. The complexity of the tester can go up from there. You might want to add some heavy duty resistors across to LED/current limiting resistors to simulate the winding resistance to check that the driver can deliver current.

 

Note that some stepper driver configuration are different to this and can actually be damaged if the motor is disconnected but AFAIK no movers use this method.

 

To test motors you'll need a simple stepper control board and a power supply. Something like this?

[Matt Cowles]

Ok here we go then, as always I will suggest that if you get stuck then please ring our Service department on (01622) 755442, but until then I will offer my best guesses for things to try.

 

FbET - It sounds as though you have a problem with the feedback circuit and not the motor circuit. The feeback circuit consists of the Opto sensor, the white encoder wheel, a wireset and the main PCB. First check that all of the teeth are in tact on the opto encoder wheel. Next check that the opto sensor is clean and clear - dust and grime can cause the sensor to get confused. Then try the sensor - you can swap the sensor from another unit or take the one from the pan circuit that you know works. Do a continuity test on the wireset from the PCB to the opto sensor. If all of this checks out then the only thing left is the main PCB. The easiest way to check is to use a PCB from another unit that you know works.

 

ShER - you have alread changed the relay, which would be my first guess. A short error occurs when the light sensor detects that the lamp is on but no lamp on command has been sent. Usually this is caused by a sticky relay but it could also be caused by the light sensor. Check the wireset up to the light sensor (although it is unlikely that this is problem) and also try swapping the lightsensor out woth a known working one. It is also worth knowing that with the covers off a unit it is possible in well lit rooms to trigger the light sensor and cause a short error, so if the error only occurs when the covers are off put a finger over the light sensor and see if the the error goes away, if so you have no problem.

 

CoER - This sounds like a wheel alignment issue. Power the unit up and let it finish its reset then move the colour wheel round so that the magnet sits underneath the hall sensor, if the magnet will not sit directly under the sensor (you should feel the steps of the motor as you move it) then it needs to be re-aligned by loosening the grub screws that hold the wheel onto the motor shaft, moving the wheel and tightening it back up.

 

CMY Falgs - This is a difficult one, it is often very difficult to get the wheels off without breaking or damaging the wheel and if anyone have any pearls of wisdom here I'd be interested to hear them. I get wheels off by using two large flat screwdrivers to lever the wheel off, with the glass try wrapping the screwdrivers in something to pretect the glass. It is always worth filing the wheel down a little so that it sits a little looser on the motor shaft when you put new wheels on motors.

 

Display loom - this can be a pig to change, you do have remove the yoke from the base, and all of the base covers. You should then be able to get to all of the cable ties you need to cut to get the wireset out. It is sometimes easier if you know that the old wireset is duff to cut the connector off the end and just pull the wires out from the other end. Then when you put a new wireset in make sure you secure it to the exisiting loom with plently of cable ties so that it cannot get caught or trapped when the fixture is moving about.

 

I hope that helps, we are on the phone if you get stuck

[Simon Brockwell]

Anyone know how to make one?

 

To test drivers you could use a spare motor but for at it's simplest you can use 4 LEDs.

 

If you look at how steppers work (Wikipedia?) you'll see that the most common configuration is to have 4 windings all with one end fed power and the other ends pulled to ground in a specific sequence. If you make a little test rig with 4 LEDs plus their series current limiting resistors you can observe the sequence as you change to pan/tilt position. If you switch down to 8-bit resolution it's much easier to see. The complexity of the tester can go up from there. You might want to add some heavy duty resistors across to LED/current limiting resistors to simulate the winding resistance to check that the driver can deliver current.

 

Note that some stepper driver configuration are different to this and can actually be damaged if the motor is disconnected but AFAIK no movers use this method.

 

To test motors you'll need a simple stepper control board and a power supply. Something like this?

 

any idea what the resistors are? I undoubtedly dont have them. :D

 

A concurrent post has been automatically merged from this point on.

 

Ok here we go then, as always I will suggest that if you get stuck then please ring our Service department on (01622) 755442, but until then I will offer my best guesses for things to try.

 

FbET - It sounds as though you have a problem with the feedback circuit and not the motor circuit. The feeback circuit consists of the Opto sensor, the white encoder wheel, a wireset and the main PCB. First check that all of the teeth are in tact on the opto encoder wheel. Next check that the opto sensor is clean and clear - dust and grime can cause the sensor to get confused. Then try the sensor - you can swap the sensor from another unit or take the one from the pan circuit that you know works. Do a continuity test on the wireset from the PCB to the opto sensor. If all of this checks out then the only thing left is the main PCB. The easiest way to check is to use a PCB from another unit that you know works.

 

What is the easiest way to remove the sensor? looks to me like you have to remove the yoke and all the plates on the arms and even then access looks tight. I have checked all the wiring and reapired a little break in the sensor loom, the encoder is intact.

 

ShER - you have alread changed the relay, which would be my first guess. A short error occurs when the light sensor detects that the lamp is on but no lamp on command has been sent. Usually this is caused by a sticky relay but it could also be caused by the light sensor. Check the wireset up to the light sensor (although it is unlikely that this is problem) and also try swapping the lightsensor out woth a known working one. It is also worth knowing that with the covers off a unit it is possible in well lit rooms to trigger the light sensor and cause a short error, so if the error only occurs when the covers are off put a finger over the light sensor and see if the the error goes away, if so you have no problem.

 

I'll give this a go thanks.

 

CoER - This sounds like a wheel alignment issue. Power the unit up and let it finish its reset then move the colour wheel round so that the magnet sits underneath the hall sensor, if the magnet will not sit directly under the sensor (you should feel the steps of the motor as you move it) then it needs to be re-aligned by loosening the grub screws that hold the wheel onto the motor shaft, moving the wheel and tightening it back up.

 

Wheel alignment is fine. I have a mini PCB sensor tester from my days at Bandit designed for the job. The LED's show that there is current in the circuit and that the sensor detects the magnet, thats why im stumped.

 

CMY Falgs - This is a difficult one, it is often very difficult to get the wheels off without breaking or damaging the wheel and if anyone have any pearls of wisdom here I'd be interested to hear them. I get wheels off by using two large flat screwdrivers to lever the wheel off, with the glass try wrapping the screwdrivers in something to pretect the glass. It is always worth filing the wheel down a little so that it sits a little looser on the motor shaft when you put new wheels on motors.

 

Display loom - this can be a pig to change, you do have remove the yoke from the base, and all of the base covers. You should then be able to get to all of the cable ties you need to cut to get the wireset out. It is sometimes easier if you know that the old wireset is duff to cut the connector off the end and just pull the wires out from the other end. Then when you put a new wireset in make sure you secure it to the exisiting loom with plently of cable ties so that it cannot get caught or trapped when the fixture is moving about.

 

Im less worried about getting the old loom out as I am putting the new one in without ripping off the connectors.

 

I hope that helps, we are on the phone if you get stuck

 

Thanks. Probably could have just called martin but its much nicer to have things in writting. Ill do my best, thanks for the info.

 

A concurrent post has been automatically merged from this point on.

 

Ok. so ive bodged the display loom by poking the wires back into the connector with a small screwdriver, its not ideal but it will work for now.

 

The color error is odd because I have tested the sensor alignment with a mini PCB sensor testers. plugged inline both straight out of the main PCB at the same time plugged into the sensor and my little LEDs are flashing away indicating that both board out out, loom and sensor are all working.

 

Ive managed to pry off the magenta flag because you can lever against the metal work, but the cyan flag being the other way up I need to lever against the glass - this is not so easy.

 

As for the short error and feedback tilt error, im sure with enoughb time I could eventually solve these issues but ive got some shows to run this week. Do martin do any lamp repairs themselves or would they recommend sending them to someone like A.C. lighting?

 

thanks for all you help.

[Matt Cowles]

We do of course repair fixtures, but so do some of our dealers, like A.C. If you wanted to send it back to us you will have to contact your Martin Dealer anyway, since the paperwork has to go through them. Either way contact your Martin Dealer and ask about the repair, they will either do the repair themselves or send it us. Either way you get a shiny working MAC 300 at the end of it.

[Simon Brockwell]

We do of course repair fixtures, but so do some of our dealers, like A.C. If you wanted to send it back to us you will have to contact your Martin Dealer anyway, since the paperwork has to go through them. Either way contact your Martin Dealer and ask about the repair, they will either do the repair themselves or send it us. Either way you get a shiny working MAC 300 at the end of it.

 

I dont know about shiny but working would be nice. I just dont have the time to do all these repairs so sending the to my dealer would be the way forward.

 

many thanks.