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Spot the deliberate mistake |
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Centauri 
Old Croc 
Joined: 29 November 2004 Location: Newcastle Aus Status: Offline Points: 1792 |
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 Posted: 03 June 2013 at 10:48am |
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Spade terminals not fully inserted into the board?
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mini-mad
Old Croc
Joined: 13 July 2012 Location: london Status: Offline Points: 6903 |
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Posted: 03 June 2013 at 10:57am |
should L1 be a feck off large wire wound resistor? ...AND the relay under specc'd? |
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If it sounds like a gorilla is trying to escape, turn it down.
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studio45
Old Croc
Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3854 |
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Posted: 03 June 2013 at 12:59pm |
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thats not a resistor, its an inductor. relay in backwards?
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Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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Peter Jan
Young Croc 
Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1012 |
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Posted: 03 June 2013 at 1:12pm |
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Shouldn't that be a 10-16A SINGLE contact relay ?
The board says LTX instead of VTX ? Don't know if that's a mistake or not... Edited by Peter Jan - 03 June 2013 at 1:17pm |
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Earplug
Old Croc
Joined: 03 January 2012 Location: Europe Status: Offline Points: 7006 |
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Posted: 03 June 2013 at 1:52pm |
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The inductor has been put in the wrong way around?
 "The board says LTX instead of VTX" That? |
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Earplugs Are For Wimps!
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service dept Steve
Old Croc
Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2030 |
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Posted: 03 June 2013 at 2:18pm |
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What's the prize?
Is it obvious and staring us in the face? or is it something subtle? It doesn't look like the relay is wrong, Yes it is only 8A but it is double pole so 16A which is correct, 24vdc coil, also correct, resistors and diode looks right, is the relay supposed to be a push away rather than a pull towards, thereby only letting the amp run in fault mode? |
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We are not "They", We are "The others"http://www.servicedept.co.uk -
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Peter Jan
Young Croc
Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1012 |
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Posted: 03 June 2013 at 3:44pm |
Wouldn't make much difference in making contact, close but still not the full 16A capacity though, no problem if the amp is in normal working order. It's not okay for breaking in a faulty situation (full rail DC for instance). Relay contacts are never 100% in "sync". The one lagging contact will almost take the full capacity the PSU can deliver into the connected speaker(s), arc itself into a solid contact and take the speaker(s) out with it. The lower the connected impedance, the easier the contacts will arc. DC rail fuses are usually roughly calculated to blow in case of a short or near short, but they hardly ever blow in a case like that. If they do, it's usually because the speakercoils have already burned into total destruction/near short-circuit. I know it's somewhat common practice to use double contact relays, on first sight it makes sense and nobody will ever notice a thing... till the amp fails. |
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slaz
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Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2675 |
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Posted: 03 June 2013 at 3:48pm |
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Magnetic field - relay and inductor could influence each other ?
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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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kedwardsleisure
Old Croc
Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4813 |
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Posted: 03 June 2013 at 8:40pm |
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There are 3 seperate faults and they're all to do with the relay.
 The prize is my undying admiration 
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Kevin
North Staffordshire |
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service dept Steve
Old Croc
Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2030 |
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Posted: 03 June 2013 at 8:53pm |
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48 volt relay, pass on the others though
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We are not "They", We are "The others"http://www.servicedept.co.uk -
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Peter Jan
Young Croc
Joined: 16 December 2008 Location: Belgium Status: Offline Points: 1012 |
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Posted: 03 June 2013 at 8:54pm |
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1) as said earlier, must be single contact.
2) is it the wrong relay maybe, as in : NC instead of NO contacts for instance ? 3) should it be another coil.. 12V, 48V or something, not 24V ? |
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kedwardsleisure
Old Croc
Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4813 |
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Posted: 03 June 2013 at 9:06pm |
 24V relay fitted - should be 48V DPDT 8A fitted - should be SPDT 16A. On Cloud amps this age, the relay is configured to short the DC bus to ground if the amp goes DC. The DC is backed up by T15A fuses in this model. I have seen otherwise healthy amps like this used on bass duty actually melt the relay covers with the heat from imperfect contacts. Quench Magnet missing. There should be a strong magnet glued to the relay to quench any DC arc before it gets established. I assume Cloud fitted these based on experience. |
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Kevin
North Staffordshire |
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kedwardsleisure wrote:
