Mac 500 Quirks & Queries

[MidgetWillis]

Hiya folks!

 

I've recently acquired 3 rather unloved Mac 500s - of which I've got 2 booting - to try and fix up as a little side project. So far most of the work has just been cleaning, oiling and reassembly but in the process some weird quirks have arisen so I figured I'd ask the hive mind! All fixtures are running software version 1.3 (I am going to update them to 2.0 but I'm still trying to get my hands on an updater tool).

 

The strangest thing is on one of the fixtures which strikes its lamp and will not lamp off. I have 'auto strike' off and 'DMX lamp off' on but everytime the fixture is powered it strikes and won't turn off. I've even tried the onboard controls to lamp off and they don't do anything either. The lamp indicator on the front is lit so it knows its on. Any ideas? I saw something on a thread for mac 300s that they have a relay that sometimes gets stuck on so could that be it?

 

The other problem may be an easier fix but the pan and tilt doesn't work on either of the booting fixtures. I've ordered some replacement drivers for the motors which I'm hoping will fix the issue but was just wondering if anyone knew of any other obvious steps I could try? When powered I can feel a stepped resistance if I try to move them so the motors seem to be receiving power.

 

Aside from those issues all I'm facing is the standard sensor errors (hopefully fixable with a good clean) and the expected struggle to source parts (though thankfully they came with almost everything they need). I've done all sorts of little electronics projects and repairs but this is the first time taking on something this intricate so any handy tips or random documentation would be super helpful.

Cheers.

[pscandrett]

The other problem may be an easier fix but the pan and tilt doesn't work on either of the booting fixtures. I've ordered some replacement drivers for the motors which I'm hoping will fix the issue but was just wondering if anyone knew of any other obvious steps I could try? When powered I can feel a stepped resistance if I try to move them so the motors seem to be receiving power.

 

If the 500s are like the old 250s then you're right, the drivers do sometimes go; however, they're socketed so you could try swapping them around (3775s, IIRC?) to see if faults move around. If none of them are working then yeah, new ones are the way to to go to try; I think the other effects (colour wheel, gobo etc) drivers are different drivers?

 

In the past IIRC I also cross-swapped pan and tilt looms (after boot) which helped narrow down where the fault was - it could well be the loom with a break in it somewhere, too, as they're quite fragile (and the 500s are old units). Do ANY of the pans or tilts work on any units?

 

Re the lamp relay getting stuck - I was taught them getting stuck sometimes means they don't strike, not the other way round, but it /could/ be that, I suppose. The recommended solution for that was a short strike with a screwdriver handle to the relay to try to loosen it. (Do this while the unit's off!). To check that it is the relay, perhaps turn auto-strike OFF on that fixture - and if it still strikes, it seems like a good things to focus on.

 

PS You mention oiling. Be careful oiling things that definitely don't need it!

[gyro_gearloose]

Try removing the tilt drive belt so there is no load on the motor. Power the unit up and see if the motor tries to move. It might judder without turning, or it might not turn but be really hard to turn by hand. If this is the case then the motor driver chip is dead. However, if you can freely spin the motor by hand while the fixture is powered then you either have a broken loom or a faulty power supply.

 

IIRC, pan and tilt use a different power supply to the other motors. There should be three LEDs on the motherboard to indicate wether the supplies are working. There might even be fuses for the motor supplies. You should have a 5 volt supply for the electronics, 12 volts for the smaller motors (colour, gobo, etc), and 24 volts for pan and tilt.

 

If the fault is with the driver chips, don’t just replace them without first trying to find the cause of the failure. Check the looms for breakage, especially where the loom passes through the pan bearing. Also check the resistors around each driver chip. The original Mac 250/300s had a failure mode where the resistors used to determine the pan/tilt motor drive current would fail, and thereby drastically reduce the current and therefore torque that the motors could use. This would then lead to juddery/no movement, and many errors on startup. Mac 500s and 600s, while using a different motherboard, can suffer the same problem.

[livewire4989]

Hiya folks!

 

I've recently acquired 3 rather unloved Mac 500s - of which I've got 2 booting - to try and fix up as a little side project. So far most of the work has just been cleaning, oiling and reassembly but in the process some weird quirks have arisen so I figured I'd ask the hive mind! All fixtures are running software version 1.3 (I am going to update them to 2.0 but I'm still trying to get my hands on an updater tool).

 

The strangest thing is on one of the fixtures which strikes its lamp and will not lamp off. I have 'auto strike' off and 'DMX lamp off' on but everytime the fixture is powered it strikes and won't turn off. I've even tried the onboard controls to lamp off and they don't do anything either. The lamp indicator on the front is lit so it knows its on. Any ideas? I saw something on a thread for mac 300s that they have a relay that sometimes gets stuck on so could that be it?

 

The other problem may be an easier fix but the pan and tilt doesn't work on either of the booting fixtures. I've ordered some replacement drivers for the motors which I'm hoping will fix the issue but was just wondering if anyone knew of any other obvious steps I could try? When powered I can feel a stepped resistance if I try to move them so the motors seem to be receiving power.

 

Aside from those issues all I'm facing is the standard sensor errors (hopefully fixable with a good clean) and the expected struggle to source parts (though thankfully they came with almost everything they need). I've done all sorts of little electronics projects and repairs but this is the first time taking on something this intricate so any handy tips or random documentation would be super helpful.

Cheers.

 

Hi,

 

When using the control menu to send a lamp off command do you hear the relay click? If not this may well mean the relay has got stuck and a careful tap should free it. If it consistently gets stuck on it is worth replacing the relay (available here if required: https://www.movinglightrepairs.com/products/martin-05000006-ic-relay-12vdc-20a-250vac-single-omron-g4a-1a-e)

 

With the pan / tilt issues if replacement drivers do not rectify the issue (they are the NJM3772 pictured here: https://www.movinglightrepairs.com/products/martin-3772-driver-chip-new-njm-pbl-njm3772-pbl3772) then it may well be due to other component failure on the motherboard. When replacing do note that the pan / tilt chips are not orientated the same way round as the other motor driver chips (check the specific IC socket for correct orientation). If you need help with this just let me know (direct email is dennis@movinglightrepairs.com). Alternatively have some refurbished good condition motherboards available here: https://www.movinglightrepairs.com/products/martin-mac-500-motherboard-main-pcb-mac500-control-card. As others have said it is important that if the fixture has damaged the motherboard that this is rectified otherwise a replacement motherboard will potentially fail in the same way.

 

If you need any further help just let me know.

 

Kind regards,

 

Dennis