Fault But Dont Know Where

[CARWYN]

Hi

I have a fault which comes and goes. but here is the scenario

 

Zero 88 desk connected to a DMX to D54 Converter which is connected to Permus Dimmers 48 channels and from the through port on the DMX to d54 converter goes off to a Zero 88 Betapack 2 which is then terminated.

 

the fault appears when in this scenario and its a kind of a slight flicker or fade between a set of channels different ones every time. its as if there's either a slight loss of power or just a flicker between 2 channels which in the main are always next-door to one another and has been turned on.

 

have used different cables and different converter and different betapack and still the same issue arises its only on the permus dimmers that the flickering happens and never on the betapack. have ruled out a DMX problem as its not that type of flicker.

 

Any help or information much appreciated

 

Carwyn

[alistermorton]

Check smoothing capacitors in the converter aren't failing - could be supply ripple?

[CARWYN]

I've had in a secondary converter and the fault still appears on that one as well

[Brian]

It sounds like the D54 decoder card in the Permus needs looking at. D54 is an analogue signal; if the timing is off, adjacent channels can get mixed up.

[Dmills]

Also, look at the grounding between the permus and the converter box, D54 was notoriously sensitive to ground 'issues'.

Push comes to shove, get a cheap DMX demux and bypass all the D54 pain completely by removing the D54 cards from the racks and going straight in with 0 - -10V.

 

Regards, Dan.

[CARWYN]

so in theory dan if there's a fault in the earth in the building the D54 will pick it up and make a deal out of it and create the issue were seeing

 

by the way the fault occurs over 2 permus racks each having 24 ways of dimming

[OllieDuff]

I've had issues with a DMX to D54 converter before, where the signal earth was intermittent, which meant that any lights powered off dimmers fed by the converter would pulse up and down. Ever since then, earthing is my first port of call if I'm having D54 issues.

 

My understanding is that DMX doesn't have this issue because with DMX the key comparison that the interface card in your dimmer makes is between the hot and cold lines, not between a signal line and earth.

[Brian]

My understanding is that DMX doesn't have this issue because with DMX the key comparison that the interface card in your dimmer makes is between the hot and cold lines, not between a signal line and earth.

Pretty much. DMX is a differential digital signal whereas D54 is unbalanced analogue, as such it behave just the same as sound. Any mains hum will manifest itself as variations in the dimmer levels.