pingue110489 Posted February 23, 2009 Share Posted February 23, 2009 Hi all,So we set up a show this weekend, with a number of channels coming into our desk (an a&h mixwizard 16:2). Most of them were floats, with 4 feeds from a desk we're submixing on. All was working fine, with absolutely no problem. Then we get feedback from an unknown channel, so I kept adding pfls till I found it coming through the 'phones. However, after half the pfls were on, the noise coming through the 'phones (and being displayed on the meter) kept cutting out 3/4 times each second. Pretty much like the sound (or occasional lack thereof) that you get from dropped packets when using digital recording. We fiddled, and it's no specific channel causing the problems - it seems pretty random as to which combination of channels it occurs on. The actual sound output is fine, it's just the pfl.We're presuming that it's a problem with the pfl circuitry - is there anything else that could be causing this? And what would be the best course of action (short of sending it off to get looked at)? For now, as long as the problem doesn't get any worse, we can just not pfl more than a couple of channels at once, though that desk gets used fairly regularly.Cheers all,Mike Link to comment Share on other sites More sharing options...
mervaka Posted February 23, 2009 Share Posted February 23, 2009 take the back off, inspect the bus. does it happen only to certain channels, or are the symptoms the same system wide? Link to comment Share on other sites More sharing options...
pingue110489 Posted February 23, 2009 Author Share Posted February 23, 2009 Shall do a proper check tomorrow evening when we get back in - it initially appears to be non-specific - we swapped channels out across the board, without finding any specific channel which caused it, or any combination of channels which may have caused it. Link to comment Share on other sites More sharing options...
KevinE Posted February 23, 2009 Share Posted February 23, 2009 Whilst you've got the back off it might be as well to buzz the white ribbon cables through, this is by far the most unreliable part of the mixwizard particularly if you use the swinging patchbay alot. Link to comment Share on other sites More sharing options...
Stee_cri1 Posted February 23, 2009 Share Posted February 23, 2009 also please bear in mind that allen and heath are rubbish solderers and it could be a dry joint. Thought you might want to check this also Hope this helps Link to comment Share on other sites More sharing options...
pingue110489 Posted February 24, 2009 Author Share Posted February 24, 2009 Hmmm. Haven't got time to take the back off it till the weekend, we're already pushed for time actually running the show! However, we tried to repeat it again today, and failed. Meaning it's an intermittent fault - could well be a bad solder joint, or something completely different. Shall let you guys know the result of any dismantling!Cheers Link to comment Share on other sites More sharing options...
aidso Posted February 26, 2009 Share Posted February 26, 2009 could it be the headphone amp over loading? you said adding pfls. this cause cause a large signal to be sent through the pfl bus. Link to comment Share on other sites More sharing options...
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