Robe ColorSpot 250AT Shutter Issues

[DarkDerp]

Hi,

We're having a very strange issue with one of our Robe fixtures.

Over DMX control, the fixture behaves perfectly, lamping on and all aspects working, except the shutter. It refuses to stay open, snapping to the level set by the controller for a split second before shutting again.

But with manual control on the fixture itself, the shutter opens and shuts as it should, so we know the control route to the actual motors is fine.

All other 250s behave properly, all are on the right mode and address.

I've tried changing address, lamps, cleaning the inside out in case of sensor issues but nothing has helped. I've also tried ringing Robe, but they recommended sending the fixture off for repair which we don't have the funds to do at the moment.

We've got access to four working 250s, so swapping any parts around won't be an issue, just need to know which part needs replacement.

Anyone got any ideas?

Many thanks.

[gyro_gearloose]

Are you changing colour or gobo when the shutter closes? I think there are menu options within the fixture to automatically close the shutter when changing colour/gobo regardless of the DMX value of the shutter channel.

[timsabre]

Presumably you have tried putting it on the same DMX address as one of the working fixtures to check for control problems?

[DarkDerp]

Yeah we've tried the same address as a working fixture with no effect and not changing color or gobo at all

[DrV]

I wonder if someone has messed with the calibration of the dimmer channel. Some of the Robe fixtures allow you to calibrate things and do stuff like set min and max levels on things. Can't be more precise but have a look at the AdJ menus, or better still read the relevant bit in the manual.

[DarkDerp]

Hi guys,

Swapped the main board with another working fixture, problem went away and stayed gone when the original main board was replaced. Not sure what the issue was, probably a loose connection somewhere. Thanks for the help!

[Don Allen]

Loose connections can return, if you get a chance, use a magnifying glass to inspect the soldering on the pcb connectors, looking for dry joints .

[marktownend]

It sounds to me like it could be a problem with the wireset leading from the PCB to the head. Seem to remember having similar issues on old heads in the past with shutters either refusing to open or close fully where a stepper motor isn't being driven on all its 'phases'. Early on in the failure this can be intermittent depending on where the head is pointing as a broken wire may only disconnect momentarily when for example the head is fully rotated in one direction. Therefore if the manual test position has the head in it's centre home position the wire may still drive the stepper. Similar thing can happen where you can't replicate the fault on the bench, but once it's upside down again in the air the dodgy wire can choose to play up again. Eventually of course the wire will fail entirely making the fault occur all the time.

 

When it plays up again, I'd suggest removing the head covers and powering it up without firing the lamp (assuming of course you know what you're doing and aren't going to frazzle yourself etc), and see if both shutters are behaving in the same way. If it is a fault as I've described then the chances are that one shutter will function perfectly whilst the other does some odd stuttering.