MAC 600E NT

[Whizzzy]

Over the winter months I have been refurbishing a pair of MAC 600E NT units and whilst everything is now complete I have a fault on one unit which is defeating me.

 

When the shutter is closed the unit should reduce the power to the lamp after 10 seconds and immediately restore to full power when the shutter is open again.

 

The problem I have is that one unit is working in reverse, in other words when the shutter is closed the lamp runs a full power after 10 seconds and when the shutter is open it reverts to reduced power. With DMX channel 1 there is a level between DMX values 116 - 122 which allows the reduced power setting to be selected however this also works in reverse in that it controls the lamp to run at full power. This could be a temporary work around but is not really satisfactory as it will differ from the other unit.

 

Monitoring the voltage on the control wires from the main pc board to the electronic ballast I see that the faulty unit is also working in reverse. There is a small voltage of around 1.2V when the shutter is closed for 10 seconds and the voltage changes to 0V when the shutter is open. Again this is the exact reverse of the good unit which outputs a small voltage to the electronic ballast when the shutter is open and changes to zero when the shutter has been closed for a short time.

 

I only have a schematic for the magnetic ballast version so I'm a little in the dark as to the full details of the lamp power control circuit but metering around there hasn't flagged up anything unusual.

 

Can anyone suggest what is going on?

 

Thanks is anticipation.

[skinda0]

When the shutter is closed the unit should reduce the power to the lamp after 10 seconds and immediately restore to full power when the shutter is open again.

 

 

I'm not familiar with these lights but just a thought. Is there a microswitch or something that detects the position of the shutter?

If there is, it sounds like NO and NC connections have been swapped which would cause this reversal of the lamp control.

[Whizzzy]

Still struggling on this one.

 

I have observed that the software version for the 'disp' differs between the two fixtures. The problem unit showing 3.0 whilst the good unit shows 2.0, but I assume this is the display and so in theory shouldn't affect the lamp power status.

 

Anyone able to provide any other pointers?

[Richard CSL]

are the shutters working correctly, not a polarity reverse issue with the stepper motors?

 

 

 

 

 

[Whizzzy]

Shutter on the defective unit is working fine. It is doing everything I would expect to see at every DMX value on channel 1. I have also traced all of the wiring to the relative stepper motor and again this corresponds to the good unit.

 

I am now leaning towards whether someone has changed the electronic ballast at some stage in the past and not realised what was going on. The defective unit has a serial number beginning with 400838**** and this now has a Schiederwerk EVG5 ballast fitted. In the 2.3 version software for the MAC 600E there was an option to select the ballast type between the Schiederwerk (post serial number break at 4020700000) and Mitronic (pre-serial number break). My present theory is that the lamp control voltage between the two electronic ballasts is working in reverse and this is why Martin provided the software selection option?

 

I have searched around on-line to try and find information on the Mitronic electronic ballast which Martin used but coming up with a blank so far.

[Whizzzy]

Final outcome - just for the record.

 

The theory about the change of ballast type seems to have been correct. After updating the CPU software with the latest MAC600E software it did provide the option to select the ballast type within the SPEC sub menu, but as the units I have are the NT version then it came up with lots of errors on the colour steppers. I then flashed the units with the current MAC 600E NT software again and bingo, problem solved. The unit is now behaving correctly by reducing the lamp power when the shutter is closed.