DavidLee Posted April 25, 2014 Share Posted April 25, 2014 Hi Just returned to a Village Hall venue to find their two Showtec Multidims dead on powering up. They've not been used for over two years but were working perfectly at the end of the last production and whilst dusty did not appear to have been affected by damp(the hall is centrally heated). Electronics were totally defunct but there was still audible transformer hum. Turned out that the 315mA quick-blow fuses on the DMX boards in each dimmer pack had failed - and replacements blew immediately in each unit. Seems odd that two separate units have failed at the same time in the same manner and in the same place. If anyone has any ideas about what may be the problem - or contact details for a repairer - I would be very grateful. I did speak to Highlite in Holland (transfered from their UK number) and was given the phone number of their UK repairer but it comes up with "number unobtainable" and Highlite couldn't offer any other contact details. Cheers David Link to comment Share on other sites More sharing options...
timsabre Posted April 25, 2014 Share Posted April 25, 2014 I'm not familiar with those units in particular, but DMX interface chips can draw a lot of current if they get zapped. I'd speculate that someone has plugged something inappropriate into the DMX line.I would try removing the DMX interface chips from the board (usually 8 pin 75176), then replace fuse and see if it blows again. Also see this threadhttp://www.blue-room.org.uk/index.php?showtopic=22129&st=15where there is a BR user who has fixed a DMX board fault. Link to comment Share on other sites More sharing options...
dmxlights Posted April 25, 2014 Share Posted April 25, 2014 I have some multidims here which have blowin that fuse a few times now and I have replaced it and they were fine but I have one now that keep blowing the fuse and I have narrowed down the fault to a capacitor near the 5 volt regulator (78L05) that went. look for any capacitors that mite have bulged on the top of them. I have heard that the 5 volt regulator (78L05) can go as well and also blow the fuse. I would have a look at them but I am in Ireland Link to comment Share on other sites More sharing options...
DrV Posted April 25, 2014 Share Posted April 25, 2014 That other thread dealt with dead triacs - the 315mA fuse won't blow regardless of what the triacs are doing. The other points are spot on though - look for a short on the low voltage rails. The other component to check which hasn't been mentioned is the bridge rectifier.Dave Link to comment Share on other sites More sharing options...
timsabre Posted April 25, 2014 Share Posted April 25, 2014 Yes, but there was a poster on the other thread who had repaired the DMX board and might have further info if contacted. Link to comment Share on other sites More sharing options...
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