Stuart91 Posted August 30, 2006 Share Posted August 30, 2006 Got an interesting problem from a customer. Not sure if it should go here or in Electrical & Power - mods, feel free to move. :blink: He has two projectors, which are being fed an SVGA signal, via a CAT 5 cable. We are using the cheap(ish) converters that CPC sell. (Link here) The problem they have is that if certain items are switched on or off, the picture cuts out. This can be something as simple as someone turning on a light switch, or a guitarist powering up their amp. The image is only lost for a split second, but obviously it's annoying them. The projectors and both CAT 5 converter boxes are all on the same ring main. There are no other problems with the picture. The immediate source of the image is a Kramer VP-23 scaler unit. I'm curious if there is some kind of power spike issue here - can anyone offer any suggestions for their electrician to investigate? I know a couple of "happy helpers" have had a go at their electrics so there may well be something adrift. Also interested if anyone out there has had any problems with the CPC CAT 5 converters. For the price I paid I expect they won't be the most robust things in the world, and I wonder if for example upgrading the mains power supplies might improve things? All suggestions welcome... Link to comment Share on other sites More sharing options...
bruce Posted August 30, 2006 Share Posted August 30, 2006 I have seen something similar - some discussion here, but no solutions... - basically we had 5 identical installs, which were getting picture loss every time the motorised screen was stopped. Starting was OK - maybe some sort of back-EMF?. Never really got to the bottom of it - the contractor replaced most of the cabling, with no success. It only appeared to affect certain Hitachi projectors. Link to comment Share on other sites More sharing options...
Andrew C Posted August 30, 2006 Share Posted August 30, 2006 Me too! Ours was fine until we ran the A/C plant, which nailed the signal completely. Tried changing the cable runs and phasing (A/C is 3Ø) all to no avail. We ended up with a long run of VGA cable. Link to comment Share on other sites More sharing options...
Stuart91 Posted August 30, 2006 Author Share Posted August 30, 2006 It only appeared to affect certain Hitachi projectors. That's very interesting, because it is Hitachi projectors that are having the problem here. (CPX-1250s to be precise) The curious thing is that it seems like any major switching operation that can trigger an interruption, with no motors involved. They have rigid screens... Link to comment Share on other sites More sharing options...
Ben... Posted August 31, 2006 Share Posted August 31, 2006 I'm curious if there is some kind of power spike issue here - can anyone offer any suggestions for their electrician to investigate? I know a couple of "happy helpers" have had a go at their electrics so there may well be something adrift.Without experience of any of that set of equipment, that'd be my first guess; big spikes appearing on the video and making the projector lose the syncs. Do you have access to a suitable oscilloscope you could use to see what happens to the video signals? Unless I'm missing something, the only ways that a lightswitch or an amp can affect the projector are either via RF interference or noise of some sort on the power supply. I'd be worried if there was enough RF interference to throw it off, so logically something is probably overly susceptible to mains spikes. Try removing/substituting bits of kit in the system to work out what the sensitive part is, and then maybe try putting a surge suppresor or mains cleaning doo-dad on it. Although it could be your cable runs that are susceptible, in which case you could try cable with better shielding. Link to comment Share on other sites More sharing options...
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