Any Mini Scan HPE experts?

[Mr Steve]

Hello,

 

A bit of a burning question - I have a Mini Scan HPE (Clay Paky) which powers up, strikes, then goes insane when DMX is applied. The unit light's the red 'data error' LED. The unit will spin around the room sometimes going to the position/beam of the cue being sent to it for a second or two, then go nuts again. As the show was a rush, and the unit used as several for beam effects rather than specific positions, it was powered down and left in the rig so I have not had it down to properly look at as yet. A colleague of mine tried changing the address to that of a neighbouring fixture, swapping the DMX cable out and terminating / removing terminaton etc. All of these variations still gave a data error. When DMX is removed it calms down.

 

Is there anything else I can check, or any known issues, or is it more likely that the main PCB in the base of the unit is toast? I will test it properly when I can get it down next week...

[Mr Steve]

Had a look at the unit today. The data error LED is dimly lit, but the unit is behaving so I'm confused as to what's going on. The same cables and terminator are being used in the testing set-up. Previously the unit was at the end of a chain of 6 on a data splitter, driven from a Vista. Now it's the one of two on an Enttec Pro for testing purposes with LightFactory.

 

Mystery.....

[DRG]

It's sounds to me like you had a bad cable somewhere else in the line, and it was just affecting that unit.

[law99]

If I remember correctly its push terminals for the DMX cable internally within the unit onto the PCB? Maybe make sure they havent got reversed and are not shorting on anything...

[Mr Steve]

UPDATE:

 

with the unit back on the Jands Vista S1, it behaves erratically. Taking it out of the DMX chain (fed from a buffer box) and plugging it in to the desk directly with a new cable, it still behaves erratically. Disconnecting it makes it stop. I'm led to believe that slowing down the DMX rate might help - does anyone know how to do this on the Vista?

[Tom Baldwin]

I'd be surprised if data rate was the problem - all of your other (presumably) identical Miniscans can cope.

 

It sounds like the DMX signal is becoming corrupted - since the problem follows the fixture, and not the cable connected to the fixture, you can assume somewhere inside the fixture is the fault - most likely a break in one side of the DMX signal.

Try metering continuity from the DMX socket back to the relevant pins of the DMX line driver IC (sorry, don't have a schematic, so I can't give you a part number, but it's highly likely to be an 8-pin DIP part, connected to the DMX socket via a couple of resistors). Hopefully you'll find a break there, and can fix it. Alternatively, try swapping out the line driver IC (hopefully it's socketed) in case it's been fried at some point. My first guesses would be either a dry joint somewhere on the PCB or a resistor that's been cooked by the heat of the lamp.