Zulu Posted May 12, 2008 Share Posted May 12, 2008 My theatre has 2 x microPAK 24 dimmers. (They are 6 x 10A single power outlets, no local control, DMX). One of them is behaving strangely: Power to all channels, but DMX control (from a Zero 88 Alcora 12/24 Channel Desk) is lost on a couple of channels. I have a couple of lanterns permanently lit when connected to those channels. A little frustrating! I have no paperwork for these dimmers, but I note that the green LEDs on the 'dodgy' dimmer are lit differently to the 'good' dimmer. Does anyone have any info on this model of dimmer, or shed any light on my problem? Thanks, Zulu Link to comment Share on other sites More sharing options...
ianknight Posted May 12, 2008 Share Posted May 12, 2008 Are you sure it's a DMX problem or Triacs blown? Do the channels stay on if you unplug the desk from the racks (so killing the DMX) in which case it's Triacs - if they go off when you unplug the desk, then try a Clear All. If its an Alcora Mk 2 - then check the DMX patch, you may have channels cross patched on odd faders! Don't worry too much about the LED's - they do age as devices (so do the circuits driving them) and so they may appear a bit different. If they are doing radically different things like flashing on and off or flickering noticeably then it may point to a control volt supply problem which may be upsetting the DMX processor in the rack. Link to comment Share on other sites More sharing options...
Zulu Posted May 12, 2008 Author Share Posted May 12, 2008 Ian,thanks for the interest. I don't know what TRIACs are. However, I can tell you that the outputs stay live when the desk is disconnected. You should know my dimmers (2 x microPAK 24 and 2 x Act 6) are connected into a zero88 Demux 24, and then the desk. So maybe the memory in the demux is confusing things? The LEDs are different, but static. thanks, Dave Link to comment Share on other sites More sharing options...
JimWebber Posted May 12, 2008 Share Posted May 12, 2008 Triacs are the electronic components within the dimmer pack that actually carry out the dimming. In the event of a power surge (Often when a lamp blows) they can get damaged, and they lock permanantly on (Or off). The only option is to get a soldering iron out and replace them (Or to be specific get someone else who knows what they are doing to replace them!) Triac Wikipedia Entry SCR Wikipedia Entry Sometimes used as an alternative to a triac. HTH Jim Link to comment Share on other sites More sharing options...
ianknight Posted May 12, 2008 Share Posted May 12, 2008 Sounds as though it is the Triacs then (the triac is essentially an electronic switch - either on or off, yours are stuck on). If you aren't confident about working inside the dimmers then find someone within your circle of friends who is, or time to find a company to repair them. The only hiccup you might find is, if the triacs are gone in the MicroPak then you may not be able to get direct replacements, this won't be so much of a problem in the ACT 6 racks. The other thing to bear in mind (depending how old it is) your Demux48 may need its internal battery replacing, this is an easy (ish) job to do and this might be the right time to get it done too! PM me if you need any more help! Ian Link to comment Share on other sites More sharing options...
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