posty07 Posted June 10, 2014 Share Posted June 10, 2014 Hi, I've got a Mac 250 with a "SHER" and it's because the lamp comes on as soon as the unit is started without a lamp on command being sent. I was wondering if anyone knew what could be causing this? The relay clicks on as soon as the unit is plugged in and won't turn off with a lamp off command, either by DMX or manual. One of the driver chips for a stepper has also gone but I wouldn't have thought that would make any difference to that circuit? There's also a problem with the 12v circuit for the fans as there is no 12v output on the board. There was until part got shorted out and now there isn't. I've been told there's another driver chip used for the 12v circuit but could anyone tell me which one it is? Any help would be greatly appreciated! Thanks in advance! Link to comment Share on other sites More sharing options...
Nicktaylor Posted June 11, 2014 Share Posted June 11, 2014 http://www.blue-room.org.uk/index.php?showtopic=20469 gives some info to check out Link to comment Share on other sites More sharing options...
posty07 Posted June 11, 2014 Author Share Posted June 11, 2014 I'd had a read through that already, unfortunately doesn't relate as his lamp isn't striking when it first starts. My problem is that the relay is constantly on so the lamp strikes before the firmware tells it to Thanks for the link though Link to comment Share on other sites More sharing options...
timmeh2 Posted June 11, 2014 Share Posted June 11, 2014 Hi If the relay is closing the second the power comes on then you've got an electrical short across the coil, pure and simple. I'd suggest that you pull the circuit board out and start tracing things, it might be linked to your loss of fan power. HTH All the bestTimmeh Link to comment Share on other sites More sharing options...
posty07 Posted June 11, 2014 Author Share Posted June 11, 2014 Thanks timmeh, will check it :) do you know what chip does control the 12v circuit? Link to comment Share on other sites More sharing options...
DrV Posted June 12, 2014 Share Posted June 12, 2014 If the relay is closing the second the power comes on then you've got an electrical short across the coil If the relay is closing then the short is across the driver chip and not the coil. do you know what chip does control the 12v circuit? Again if the relay is closing then the 12V is probably fine. However, the fans and the relay are all controlled by IC307 which is the ubiquitous ULN2803A. That would easily be damaged by a short on your fan wiring. You can check the 12V level on pin 10 of the chip. (0V on pin 9). BTW the 5V rail is derived from the 12V rail so if you're getting displays etc then both of those rails are probably OK. HTHDave Link to comment Share on other sites More sharing options...
posty07 Posted June 12, 2014 Author Share Posted June 12, 2014 Thanks very much for that Dave, so basically it's pointing towards that chip being wrecked? Link to comment Share on other sites More sharing options...
DrV Posted June 12, 2014 Share Posted June 12, 2014 Thanks very much for that Dave, so basically it's pointing towards that chip being wrecked?Yes Link to comment Share on other sites More sharing options...
jamieshurlock Posted June 12, 2014 Share Posted June 12, 2014 Could be a sticky relay, try checking the lamp sensor as well as I've had similar problems in the pastIf you need the those chips to replace I have them in stock, if your not into surface mount repairs I can do that here as it's a fairly common fault.sales@jamiesmagictorch.co.uk Link to comment Share on other sites More sharing options...
posty07 Posted June 12, 2014 Author Share Posted June 12, 2014 Definitely not a sticky relay as I can see it clicking on and off, thanks, I've got a local shop that does them, if not I'll send you an email :) Link to comment Share on other sites More sharing options...
posty07 Posted June 18, 2014 Author Share Posted June 18, 2014 So replaced that chip and it fixed all the problems I was having :') thanks Dave! Now just to replace a stepper driver to restore to perfection! Link to comment Share on other sites More sharing options...
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