MAC 500 Won't Lamp On

[fazJ]

Hi, I have a MAC 500 that after a power cut now refuses to lamp on.

 

I have tried both DMX and local lamp on and neither work, however when set to DMX lamp on it does show a SERR but does not when set to Auto Lamp.

When lamping on locally you can hear the lamp circuit click in and the lamp LED on the screen panel also comes on indicating it is struck however the lamp still fails to strike. It may also click on when on DMX lamp on but I haven't been able to get it near enough to the desk to hear it click in.

I have replaced the lamp with both known working used lamp and a brand new lamp just to be sure.

I have also tried sending the lamp off command and waiting for 10 minutes before trying to re-strike to no avail.

 

Any help would be much appreciated.

[DrV]

Igniter is your next port of call then. Although if you are competent and safe with a good quality mains meter you could check the voltage at the connecting block in the side arm. If the ballast is OK and the lamp relay is switching on correctly then you should get approximately mains voltage at this point after you have given a lamp on. This will stay at this voltage if the igniter is not managing to strike the lamp. If you don't get mains voltage there, then there is a fault with the ballast or the relay or the wiring below that point. Usual caveat applies ; this is mains voltage and dangerous. If you don't know what you're doing then stay away from it.

 

As you say it happened after a power cut I think the igniter is the most likely cuplrit.

 

HTH

Dave

[fazJ]

Ahh thank you, I was really hoping you weren't going to say the igniter, possibly the least accessible component in the unit, thank you I shall give it a try,

 

I can now comfortably say that it is not the igniter as I had a spare unit that has been decomissioned into spare parts and it turns out it still wont lamp on, I have also tried swapping the circuit board over between units and it still wont lamp on.

 

Any more suggestions would be very very welcome.

[PaulDF]

Be very careful if using a volt meter in there with a live ignitor/ballast combination - you can have thousands of volts in there! The volt meter may not like having that sort of voltage shoved across it either.

Talking generally as I don't have experience in MAC500, only the older Roboscans, have you tried measuring the resistance across the ballast? Failing that it is a case of ensuring there is power to the lamp circuit (I'd look to disable the ignition first) and then bell each cable and the lamp holder out.

[DrV]

I can now comfortably say that it is not the igniter as I had a spare unit that has been decomissioned into spare parts and it turns out it still wont lamp on, I have also tried swapping the circuit board over between units and it still wont lamp on.

 

Any more suggestions would be very very welcome.

 

Did you check the connecting block in the side arm? That's a useful midpoint for determining which part of the circuit is faulty.

 

Be very careful if using a volt meter in there with a live ignitor/ballast combination - you can have thousands of volts in there! The volt meter may not like having that sort of voltage shoved across it either.

Paul's right about the high voltages beyond the igniter, but there is "only" mains voltage at the connecting block. The igniter is, as you have seen, above this in the head.

Dave

[JohnMac]

Another component to check is the thermal cut off trip , mounted just behind one of the fans, these normally should have closed contacts, opening if the temperature exceeds 150 degrees C. Sometimes these switches fail open circuit.

Regards

 

John Mac.