nolascratch Posted June 11, 2008 Share Posted June 11, 2008 Hello All, I just inherited a whole slew of instruments with lots of problems, so I was able to fix most of them, but a few problems are still confounding me. I have a Mac 2000 Profile that has suddenly decided it no longer wants to pan for me. The motors vibrate upon startup but will not home the instrument and once it is up and running I cannot manually pan from the manual controls as well. There is nothing physically preventing the head from panning as it swings freely when there is no power to the instrument. The pan motors have power going to them as they are energized and providing resistance when the instrument is powered up. They just won't tell it to move. If you give the head a nudge it will sometimes pan by itself for a little bit during the initial homing sequence. So far I have done the following: Swapped out the PCB with a known good board to make sure it wasn't just a logic error.Tested the wire looms for shorts to the Pan motors as well as to the Pan sensor.Cleaned out the pan sensor.Examined the Pan sensor wheel for broken teeth.Removed PAN belt to see if the motors would act normal with no resistence on them. They did. I am just kind of at an impasse now. Suggestions? -Scratch Link to comment Share on other sites More sharing options...
HobitLight Posted June 11, 2008 Share Posted June 11, 2008 Suggestions?Only one, I'm afraid. Once we had a MAC 250 (original) which couldn't pan either. I'm not entirely sure but I think that it could pan freely when the power was off. On the pan cog there is a little block of metal (copper?) which moves with it. To find HOME the fixture pans around until this piece of metal pushes a thin strip of metal which is basically a switch. The fixture then knows where the yoke's pan is because the piece of metal is touching the switch so it moves to HOME. The problem was that this piece of metal had moved down a bit so got caught on the switch and kept on trying to push past it. We had taken part of the top of the base of and was looking to see what was wrong with it. Have a look with the power on and see if this is he problem. Hope this helps! <_< P.S. I just inherited a whole slew of instrumentsIf there's any you don't want... :unsure: Link to comment Share on other sites More sharing options...
niclights Posted June 11, 2008 Share Posted June 11, 2008 Alternatively have you tried swapping pan sensor with another unit? Link to comment Share on other sites More sharing options...
nolascratch Posted June 11, 2008 Author Share Posted June 11, 2008 Alternatively have you tried swapping pan sensor with another unit? Yeah I swapped out the pan sensor with another unit. No change at all in my results. A concurrent post has been automatically merged from this point on. Suggestions? The problem was that this piece of metal had moved down a bit so got caught on the switch and kept on trying to push past it. We had taken part of the top of the base of and was looking to see what was wrong with it. Have a look with the power on and see if this is he problem. No, I know exactly what you are talking about as I have had that same problem on another Mac a few months back, but the switch and metal trigger plate are in the proper position. If you manually rotate it around and trip the switch, it stops sending power to the motors as it has found it's home start. So no luck there. See why this thing is confounding me? Link to comment Share on other sites More sharing options...
scjb Posted June 11, 2008 Share Posted June 11, 2008 Might it be worth swapping the driver IC's from pan to tilt and vice-versa? Sounds conceivable that the driver has popped and is just permanently energising a set of coils preventing normal operation. Of course, you might pop the other chip as well, but it's worth a go IMHO. Link to comment Share on other sites More sharing options...
maeterlinck Posted June 12, 2008 Share Posted June 12, 2008 You haven't mentioned swapping the Pan stepper. If the motor has an issue it might appear Ok under no-load but won't have enough torque with.You can swap the Pan and Tilt steppers (I think for a 2K - someone correct me if I'm wrong here) so the Pan stepper is driven by the Tilt driving circuit. This should indicate if the motor is ok or not as you've confirmed the Tilt is fine. I wouldn't let it do a full reset as it's going to get horribly confused.HTH Link to comment Share on other sites More sharing options...
ceecrb1 Posted June 12, 2008 Share Posted June 12, 2008 This sounds to me more like a sensor related problem rather than a motor circuit problem. If you dont know, stepper motors are controled by 2bit data signal, ie the driver just "counts" up and down in binary.. the faster it counts.. the faster the motor spins... To me it sounds like an identical problem I had (except for me it was frost) 2 weeks ago...In my case one of the fixtures hal sensors was not working and so it was booting/reseting without the index point programmed.For this reason, the fixture does not know where it is, and where it can or cannot move to, or by how much you have moved it by when you bump it. Try swapping the pan sensor with one from a working machine and boot it up... The macs errors are extremely helpful, but at times are very deceieving false friends... Usually the point to the actual effect rotation as the problem where it is the sensor or visa-versa... Link to comment Share on other sites More sharing options...
Guest joewhite903 Posted June 12, 2008 Share Posted June 12, 2008 It sounds as though one wire on the motor loom as become broken, A broken wire will give you motor activity buzzing humming but thats about all it will do, A blown driver you will get nothing whats so ever. Joe Link to comment Share on other sites More sharing options...
scjb Posted June 12, 2008 Share Posted June 12, 2008 A blown driver you will get nothing whats so ever. That's not strictly true. If you have a stepper tester (a box with 4 leds on it that indicate the output of the driver IC) you can see several distinctly different failure modes, viz... 1. no output from the driver at all (no leds lit\no coils energised so motor shaft can be turned easily)2. full output from the driver (all leds permanently lit\all coils energised so motor shaft stiff to turn)3. one or more outputs stuck on whilst the others are normal (one or more leds stuck on, whilst the others cycle as normal\one or more coils permanently energised so motor shaft has difficulty moving in it's normal fashion, but can be "manually encouraged")4. one or more outputs stuck off whilst the others are normal (one or more leds stuck off, whilst the others cycle as normal\one or more coils permanently unenergised so motor shaft has less torque than normal and tends to stall, but can "pretend" normal movement whilst not under load) I'm currently in driver IC hell fixing some very unloved 250's and roboscans and have observed a variety of the above in the last couple of days. It sounded a little to me as if the symptoms the OP was describing could be caused by the fourth possibility (amongst other things). EDIT: Clumsy English (still not brilliant) Link to comment Share on other sites More sharing options...
KevinE Posted June 12, 2008 Share Posted June 12, 2008 Surely if you've changed the boards and it hasn't fixed it, and you're sure the looms are ok, and you've swapped the sensors, and the transmission (IE belts n cogs) are ok then it must only be the motor? It's the only thing left!?? Link to comment Share on other sites More sharing options...
RobOwen Posted June 12, 2008 Share Posted June 12, 2008 Surely if you've changed the boards and it hasn't fixed it, and you're sure the looms are ok, and you've swapped the sensors, and the transmission (IE belts n cogs) are ok then it must only be the motor? It's the only thing left!?? There are two motors though, shouldn't it at least move a bit, I assume each has a seperate driver chip. I agree with Ceecrb in that I don't think it's getting it's initial reference point so maybe will not move. Mind you does the fixture hit the mechanical stop and "bounce" when homing? If it doesn't then something far more sinister is at work. Maybe the optical encoder is not working properly and the drive logic knows it is sending a signal to move the motors (hence the small amount of movement), but it is not getting confirmation from the encoder so stops. This could be a safety routine in software, maybe? Martin reps are on this forum, but I don't know how often they look. You will probably get a response from Martin Canada on the LightNetwork, who may know more specifics on this problem. EDIT: The more I think of it the more it does sound like a dead motor, giving the other motor a hard time, hence when you give it a helping hand it does move a bit. Try disconnecting one motor and see what happens, then if its still try it the other way round (turn the fixture off first or the driver chip might catch fire!!) Link to comment Share on other sites More sharing options...
ceecrb1 Posted June 12, 2008 Share Posted June 12, 2008 OR just remove teh bands between the motor and fixture.. see how they react at bootup. One thing I have learned about my last year repearing macs... its ALWAYS a daft simple thing you didnt bother to look at because you thought it wasnt that...... Link to comment Share on other sites More sharing options...
maeterlinck Posted June 12, 2008 Share Posted June 12, 2008 ...its ALWAYS a daft simple thing you didnt bother to look at because you thought it wasnt that...... Unfortunately yes. Problems usually start with little issues, and with electronics often stop there as the device stops working... Link to comment Share on other sites More sharing options...
nolascratch Posted July 17, 2008 Author Share Posted July 17, 2008 Just to update... It turns out the logic board WAS the problem. I had swapped it out with a "known good logic board" and had the same error. Well, it turns out that the person who said it was a "known good logic board" was full of BS. Both boards had a similar problem and once I swapped it with a good board the whole instrument worked fine. Which I wish I would have known before I took the head off and replaced both pan motors. Ah well... But thanks for all the help and suggestions, you have certainly given me more avenues to explore when I run into other problems. Link to comment Share on other sites More sharing options...
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