MAC 550 185 Degrees F???

WayneOgle

Member
Joined
Jun 30, 2017
Location
Washington
Hello all, this is a bit of a tricky one. I have a Mac 550 here that thinks its temperature sensor is reading 185 Degrees Fahrenheit and therefore shutting off 7 seconds after lamp on. So far I've replaced the thermo-sensor, Thermo-switch, separated the feedback cables form the main power by the E-ballast, and changed out the circuit boards as well as cleared out any lamp hours and strikes from the memory of the fixture. Any thoughts?
 

MNicolai

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Mar 30, 2008
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Sarasota, FL
Is it reading an actual error message like LERR or THER or does it just lamp off without any indication as to why?

Filters and so forth cleaned up?

Was the fixture previously working for you and recently started doing this or did it show up on your door step in this condition?

Do you have a second fixture available you can swap parts around with to do a little process of elimination?

Have you verified the fixture is set to the correct voltage internally?
 

WayneOgle

Member
Joined
Jun 30, 2017
Location
Washington
Is it reading an actual error message like LERR or THER or does it just lamp off without any indication as to why?

Filters and so forth cleaned up?

Was the fixture previously working for you and recently started doing this or did it show up on your door step in this condition?

Do you have a second fixture available you can swap parts around with to do a little process of elimination?

Have you verified the fixture is set to the correct voltage internally?
No error message but when I go to the Info tab under the menu of the fixture and select fixture lamp sensor its reading at 180 F when it is lamped off.
And yes I've already gone through and cleaned the fixture as well, sadly when I got to the theatre it's been doing this so I have no prior experience with this light in the rig and no history of it.
I do have a second fixture which is a good idea.
And I have verified the voltage.
 

MNicolai

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Sarasota, FL
That is indeed strange. Normally you would get a LERR or THER if one of the lamp or thermal sensors was on the fritz or if it was an honest thermal issue. The error message would persist even after the lamp is doused. Does it maintain a reading of 180F after the lamp's become doused and been cool for awhile or does it start to shift back to a more realistic ambient room temperature reading?

If you've done the obvious troubleshooting steps and there's little reason to believe it's actually a thermal issue, I would investigate the main PCB for obvious signs of scorched electronics. I had an older MAC about 18 months ago that had an IC on the main PCB fry in the socket and send the fixture into a long overdue grave.

Also could be a ballast/starter issue, which if the main PCB swap is successful, will pretty quickly narrow down for you the possibilities of what it could be.
 

WayneOgle

Member
Joined
Jun 30, 2017
Location
Washington
Thanks for your input!

I've already swapped the main PCB and the issue is still persisting. Also the Thermal Sensor is reading 180 before the lamp is struck and once it is struck only stays on for 7 seconds before dousing itself and still reads at a consistent 185 degrees Fahrenheit. I've also replaced the electronic ballast in the fixture and even separated the output wires and the feedback wires from the ballast (found a Martin PSA that mentioned this was an issue with this specific problem on this fixture). Haven't tried swapping the starter yet so that might be next on my agenda.
 

MNicolai

Well-Known Member
Fight Leukemia
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Mar 30, 2008
Location
Sarasota, FL
You could hit the thermal sensor with a heat gun briefly and see if it shows any sign of life. If it doesn't show any proof of anything I would be inclined to think there's an issue somewhere in that sensor's circuit.

Hard to know if it temp reading is the cause or just a symptom, but since the main PCB checks out I'm a little more tempted to think it may be the cause.

I assume you've long ago seen this thread.
 

cbrandt

Well-Known Member
Joined
Dec 7, 2011
Location
Michigan
Have you changed the lamp? Are you testing with DMX, or just manual commands on the fixture? I've frequently run into problems with Martin fixtures that are set to douse the lamp without dmx, doing so even while running the internal test sequences.
 
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