Atom Feed - Twisted Pear Audio Support - Topic:Rectifier Blowing in in new Placid BP after heavy use - 20Twisted Pear Audio Support - Atom Feedurn:twistedpearaudio-com:AtomFeed:TwistedPearAudioSupport:Topic:RectifierBlowingininnewPlacidBPafterheavyuse-20:1Copyright 2024 Twisted Pear Audio Support2024-03-29T13:30:28Zhttp://www.twistedpearaudio.com/forum/Images/YAFLogo.pngForum Adminhttp://www.twistedpearaudio.comfeedback@twistedpearaudio.combiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-Doneganbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-Doneganbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-Doneganbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-Doneganbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdRuss Whitehttp://www.twistedpearaudio.com/forum/profile/9-Russ-Whitebiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-DoneganBrian Doneganhttp://www.twistedpearaudio.com/forum/profile/8-Brian-Doneganbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdavr300http://www.twistedpearaudio.com/forum/profile/396-avr300biggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdbiggsdhttp://www.twistedpearaudio.com/forum/profile/25738-biggsdYetAnotherForum.NETurn:twistedpearaudio-com:ftPosts:st1:meid25664:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Yes, i have a full test rig now. 2 x desktop power supplies with current limiting.<br /><br />Spare legato board as a load.<br /><br />Test rig works and i can definitely test working boards. Tested some old placid 1.0 boards with rig and all test fine. 15v output, 50ma shunt, so my testing platform is all working fine.<br /><br />I have two failed PLACID 2.1 boards. All faulty on + side.<br />Board 1: (and was in the most recent fault with blowing rectifier):<br />15v no load output no problem.<br />When i add the load, i can maintain 15v BUT only if the shunt current is like 90ma. <br />As soon as i drop the shunt current using the pot to 50ma, the voltage drops to like 10v. <br />vref is 2.48 v.<br /><br />Board 2: <br />it was behaving as above. But then suddenly it went short circuit <br />Current limiting input using power supply. had it up to 1a and it still wants more.<br />I have replaced all of the actives - 7 transistors - including shunt ones - still is showing short circuit.<br />Could IC1 be a fault? <br />What should i replace next?<br /><br />maybe can someone help me with any more tests I can do?</td></tr></table>2019-06-01T11:06:40-07:002019-06-01T11:06:40-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Yes, i have a full test rig now. 2 x desktop power supplies with current limiting.<br /><br />Spare legato board as a load.<br /><br />Test rig works and i can definitely test working boards. Tested some old placid 1.0 boards with rig and all test fine. 15v output, 50ma shunt, so my testing platform is all working fine.<br /><br />I have two failed PLACID 2.1 boards. All faulty on + side.<br />Board 1: (and was in the most recent fault with blowing rectifier):<br />15v no load output no problem.<br />When i add the load, i can maintain 15v BUT only if the shunt current is like 90ma. <br />As soon as i drop the shunt current using the pot to 50ma, the voltage drops to like 10v. <br />vref is 2.48 v.<br /><br />Board 2: <br />it was behaving as above. But then suddenly it went short circuit <br />Current limiting input using power supply. had it up to 1a and it still wants more.<br />I have replaced all of the actives - 7 transistors - including shunt ones - still is showing short circuit.<br />Could IC1 be a fault? <br />What should i replace next?<br /><br />maybe can someone help me with any more tests I can do?</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25656:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Do the Placids always fail at a venue, or has it also happened at home?<br /><br />I am still trying to figure out what could be causing the failures. I have never heard of this type of failure from other users, so there must be some anomaly we can identify (or this has happened elsewhere and I have not heard about it <img src="/forum/Images/Emoticons/eusa_whistle.gif" alt="Whistle" /> ). <br /><br />My current thinking (no pun intended) is that there is a DC voltage (pr something) present on the ground lines of the venue that is causing something strange to happen when you power up there.<br /><br />.</td></tr></table>2019-05-28T14:19:58-07:002019-05-28T14:19:58-07:00Brian Donegan<table class="content postContainer" width="100%"><tr><td>Do the Placids always fail at a venue, or has it also happened at home?<br /><br />I am still trying to figure out what could be causing the failures. I have never heard of this type of failure from other users, so there must be some anomaly we can identify (or this has happened elsewhere and I have not heard about it <img src="/forum/Images/Emoticons/eusa_whistle.gif" alt="Whistle" /> ). <br /><br />My current thinking (no pun intended) is that there is a DC voltage (pr something) present on the ground lines of the venue that is causing something strange to happen when you power up there.<br /><br />.</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25655:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Yes, the placid and the legato all through the ground screws?<br /><br />transformers no, but thats normal.<br /><br />any other tests i can do on the faulty placid?</td></tr></table>2019-05-22T08:55:49-07:002019-05-22T08:55:49-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Yes, the placid and the legato all through the ground screws?<br /><br />transformers no, but thats normal.<br /><br />any other tests i can do on the faulty placid?</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25654:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Are you grounding anything to the case?</td></tr></table>2019-05-21T20:48:21-07:002019-05-21T20:48:21-07:00Brian Donegan<table class="content postContainer" width="100%"><tr><td>Are you grounding anything to the case?</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25653:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Hi Brian<br /><br />it is definitely black/red on positive side. That’s where the fault originally occurred. Orange yellow on negative.<br /><br />Again it was running perfect for 2 years with daily switch on / off - so maybe a part fatigued?<br /><br />Right now replaced the placids with new ones and all working.<br /><br />But reallly keen to fix these broken ones. <br /><br /><br /><br /><br /><br /></td></tr></table>2019-05-21T20:13:12-07:002019-05-21T20:13:12-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Hi Brian<br /><br />it is definitely black/red on positive side. That’s where the fault originally occurred. Orange yellow on negative.<br /><br />Again it was running perfect for 2 years with daily switch on / off - so maybe a part fatigued?<br /><br />Right now replaced the placids with new ones and all working.<br /><br />But reallly keen to fix these broken ones. <br /><br /><br /><br /><br /><br /></td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25652:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>I was looking for specifics on the transformer secondaries and their connection to the Placid, just to rule it out as a possible cause of the issue.<br /><br />Something like this:<br /><br /><img src="http://www.twistedpearaudio.com/forum/resource.ashx?i=2033&b=1" alt="UserPostedImage" class="UserPostedImage" style="max-width:200px;max-height:200px" /><br /><br />Black/Red to positive side, Orange/Yellow to negative side.<br /><br /><br /><br /><br /><br /><br />.</td></tr></table>2019-05-21T19:37:54-07:002019-05-21T19:37:54-07:00Brian Donegan<table class="content postContainer" width="100%"><tr><td>I was looking for specifics on the transformer secondaries and their connection to the Placid, just to rule it out as a possible cause of the issue.<br /><br />Something like this:<br /><br /><img src="http://www.twistedpearaudio.com/forum/resource.ashx?i=2033&b=1" alt="UserPostedImage" class="UserPostedImage" style="max-width:200px;max-height:200px" /><br /><br />Black/Red to positive side, Orange/Yellow to negative side.<br /><br /><br /><br /><br /><br /><br />.</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25651:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>They are 80VA transformers. Why? Because it really makes a big difference to the low end in the legato. <br /><br />Same circuit as per design but much larger rectifiers. <br /><br />Transformers -> Rectifiers -> Placid<br /><br />Just jumpered the inputs there the small rectifiers were. rectifiers supplying 20v DC.<br /><br />this design has worked no problem for 2 years.<br /><br />Keen to figure out what may have happened and what parts under the most stress after the recftifiers. so can upgrade. Happy to just have spares available if it happens again.<br /><br />Thanks Brian, i also have some spare QP3-QP5 - worth trying those next? Or any measurements i could take?<br /><br /><br /><br /><br /></td></tr></table>2019-05-21T19:30:15-07:002019-05-21T19:30:15-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>They are 80VA transformers. Why? Because it really makes a big difference to the low end in the legato. <br /><br />Same circuit as per design but much larger rectifiers. <br /><br />Transformers -> Rectifiers -> Placid<br /><br />Just jumpered the inputs there the small rectifiers were. rectifiers supplying 20v DC.<br /><br />this design has worked no problem for 2 years.<br /><br />Keen to figure out what may have happened and what parts under the most stress after the recftifiers. so can upgrade. Happy to just have spares available if it happens again.<br /><br />Thanks Brian, i also have some spare QP3-QP5 - worth trying those next? Or any measurements i could take?<br /><br /><br /><br /><br /></td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25650:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>I think we have talked about this before, but I can't remember now...<br /><br />What transformers are you using, and how do you have them wired to the Placids?<br /><br /></td></tr></table>2019-05-21T13:49:11-07:002019-05-21T13:49:11-07:00Brian Donegan<table class="content postContainer" width="100%"><tr><td>I think we have talked about this before, but I can't remember now...<br /><br />What transformers are you using, and how do you have them wired to the Placids?<br /><br /></td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid25649:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Hi there everyone!<br /><br />So i now have a new problem that is related to the first problem.<br /><br />I have upgraded all the rectifiers and it has lasted a good 2 years .,... then POP.<br /><br />Both boards in close to the same period. Smoke and high current. Seems to always be on the Plus side.<br /><br />Got it out and put on some bench current limited supplies with 20v DC - so discounting the rectifiers now and we are past them.<br /><br />Tests as follows: <br />Note: these issues only on positive side<br /><br />Tests as follows (all is for plus side, negative rail is all good)<br /><br />NO LOAD - Draws normal 250ma current, 15v DC - so all looks ok<br />ADD LEGATO LOAD - Voltage drops to 10v and <br />Then it tried to draw a lot of current 30 seconds later - supplies limited it at 300ma<br />NOW:<br />total current draw is 80ma.<br />0 voltage<br /><br />So i now have a clearly faulted board. Other board had exactly the same fault.<br /><br />I really want to figure out what parts are failing.<br /><br />So far: <br />Replaced QN1 and QN2 - no change 0 - still 80ma current and no voltage. So its definitely not heat.<br /><br />Keen to understand what else i can test, and i can also replace QP3-5 next. <br /><br />Any other ideas as to what might have caused fault, or most loaded part?<br /><br />Remember i have large trannies and massive rectifiers so its the next part in the chain that takes current when inrush happens on switch on.<br /><br />Keen for thoughts and feedback. <br /><br /></td></tr></table>2019-05-21T05:31:26-07:002019-05-21T05:31:26-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Hi there everyone!<br /><br />So i now have a new problem that is related to the first problem.<br /><br />I have upgraded all the rectifiers and it has lasted a good 2 years .,... then POP.<br /><br />Both boards in close to the same period. Smoke and high current. Seems to always be on the Plus side.<br /><br />Got it out and put on some bench current limited supplies with 20v DC - so discounting the rectifiers now and we are past them.<br /><br />Tests as follows: <br />Note: these issues only on positive side<br /><br />Tests as follows (all is for plus side, negative rail is all good)<br /><br />NO LOAD - Draws normal 250ma current, 15v DC - so all looks ok<br />ADD LEGATO LOAD - Voltage drops to 10v and <br />Then it tried to draw a lot of current 30 seconds later - supplies limited it at 300ma<br />NOW:<br />total current draw is 80ma.<br />0 voltage<br /><br />So i now have a clearly faulted board. Other board had exactly the same fault.<br /><br />I really want to figure out what parts are failing.<br /><br />So far: <br />Replaced QN1 and QN2 - no change 0 - still 80ma current and no voltage. So its definitely not heat.<br /><br />Keen to understand what else i can test, and i can also replace QP3-5 next. <br /><br />Any other ideas as to what might have caused fault, or most loaded part?<br /><br />Remember i have large trannies and massive rectifiers so its the next part in the chain that takes current when inrush happens on switch on.<br /><br />Keen for thoughts and feedback. <br /><br /></td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23688:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Hi Team just thought i would share the issue was simply the rectifier as i was often plugging into a 32a supply. So put some big grunty rectifiers in and no more issues </td></tr></table>2016-01-13T10:49:06-07:002016-01-13T10:49:06-07:00biggsd<table class="content postContainer" width="100%"><tr><td>Hi Team just thought i would share the issue was simply the rectifier as i was often plugging into a 32a supply. So put some big grunty rectifiers in and no more issues </td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23016:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Legato is current limited by the CCS part of the circuit - so the only way the output could have seen a lot of current would have been if the CCS portion was somehow shorted or failed in a short.<br /><br />Unfortunately if that happened you may have lots of dead actives.. :(<br /><br />Sorry<br />Russ</td></tr></table>2015-08-25T21:27:22-07:002015-08-25T21:27:22-07:00Russ White<table class="content postContainer_Alt" width="100%"><tr><td>Legato is current limited by the CCS part of the circuit - so the only way the output could have seen a lot of current would have been if the CCS portion was somehow shorted or failed in a short.<br /><br />Unfortunately if that happened you may have lots of dead actives.. :(<br /><br />Sorry<br />Russ</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23014:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Yes I assumed it could have been QP1/QP2, but when i have seen the fault its only the rectifier that blows. Yes thats correct there is another whole Placid/legato assembly working perfectly off the same power source.<br /><br />In looking at the underside of the board, on the output of the Placid between - and gnd its looks like it has heated quite a bit.. saying that possibly a lot of current has gone through the output on the side that blew up. the positive side doesn't have this. So, therefore, is it possible that the legato now has some kind of short/faulty part that could be shorting the output of the placid, thereby blowing the rectifier due to over current?<br /><br />That is the big question because if that possibly the case, i will look at the legato<br /><br />Good idea about the fuse, that will save me damaging boards... :-)</td></tr></table>2015-08-25T21:22:00-07:002015-08-25T21:22:00-07:00biggsd<table class="content postContainer" width="100%"><tr><td>Yes I assumed it could have been QP1/QP2, but when i have seen the fault its only the rectifier that blows. Yes thats correct there is another whole Placid/legato assembly working perfectly off the same power source.<br /><br />In looking at the underside of the board, on the output of the Placid between - and gnd its looks like it has heated quite a bit.. saying that possibly a lot of current has gone through the output on the side that blew up. the positive side doesn't have this. So, therefore, is it possible that the legato now has some kind of short/faulty part that could be shorting the output of the placid, thereby blowing the rectifier due to over current?<br /><br />That is the big question because if that possibly the case, i will look at the legato<br /><br />Good idea about the fuse, that will save me damaging boards... :-)</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23013:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Yes I assumed it could have been QP1/QP2, but when i have seen the fault its only the rectifier that blows. Yes thats correct there is another whole Placid/legato assembly working perfectly off the same power source.<br /><br />In looking at the underside of the board, on the output of the Placid between - and gnd its looks like it has heated quite a bit.. saying that possibly a lot of current has gone through the output on the side that blew up. the positive side doesn't have this. So, therefore, is it possible that the legato now has some kind of short/faulty part that could be shorting the output of the placid, thereby blowing the rectifier due to over current?<br /><br />That is the big question because if that possibly the case, i will look at the legato<br /><br />Good idea about the fuse, that will save me damaging boards... :-)</td></tr></table>2015-08-25T21:18:42-07:002015-08-25T21:18:42-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Yes I assumed it could have been QP1/QP2, but when i have seen the fault its only the rectifier that blows. Yes thats correct there is another whole Placid/legato assembly working perfectly off the same power source.<br /><br />In looking at the underside of the board, on the output of the Placid between - and gnd its looks like it has heated quite a bit.. saying that possibly a lot of current has gone through the output on the side that blew up. the positive side doesn't have this. So, therefore, is it possible that the legato now has some kind of short/faulty part that could be shorting the output of the placid, thereby blowing the rectifier due to over current?<br /><br />That is the big question because if that possibly the case, i will look at the legato<br /><br />Good idea about the fuse, that will save me damaging boards... :-)</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23004:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td><div class="quote"><span class="quotetitle">Quote:</span><blockquote>Trying to troubleshoot an issue but keen to get a response on exactly what the impact of a placid BP overheating is...<br /><br />What parts are likely to fail? Could this cause shorts anywhere?</div></div><br /><br />QN1/2 and QP1/2 will be the parts to overheat. If they fail, they will fail permanently, probably letting out smoke. This is speculation, and depends on other factors, such as the failure mode causing the heat). I have never smoked one, so I do not know for sure.</td></tr></table>2015-08-25T16:57:08-07:002015-08-25T16:57:08-07:00Brian Donegan<table class="content postContainer" width="100%"><tr><td><div class="quote"><span class="quotetitle">Quote:</span><blockquote>Trying to troubleshoot an issue but keen to get a response on exactly what the impact of a placid BP overheating is...<br /><br />What parts are likely to fail? Could this cause shorts anywhere?</div></div><br /><br />QN1/2 and QP1/2 will be the parts to overheat. If they fail, they will fail permanently, probably letting out smoke. This is speculation, and depends on other factors, such as the failure mode causing the heat). I have never smoked one, so I do not know for sure.</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23003:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>This is only happening on one of the two Placid HD BPs? The other Legato/Placid are working fine?<br /><br />Is the venue you mentioned the same place where this keeps happening? <br /><br />There are two possible things that will kill a rectifier like that: over-voltage fro the transformer (doubtful) or excessive current draw (a short). "In rush" current is not your problem. There is not enough capacitance on the Legato to cause that sort of problem. It's more likely a plain old intermittent short, either in the wiring/soldering, or a bad part, such as a cap or transistor.<br /><br />I would install a fuse between the transformer and the Placid to protect it moving forward. Something like a 1A slow-blow. Typically this is not needed, but it will save you from killing boards while you track this down.</td></tr></table>2015-08-25T13:06:58-07:002015-08-25T13:06:58-07:00Brian Donegan<table class="content postContainer_Alt" width="100%"><tr><td>This is only happening on one of the two Placid HD BPs? The other Legato/Placid are working fine?<br /><br />Is the venue you mentioned the same place where this keeps happening? <br /><br />There are two possible things that will kill a rectifier like that: over-voltage fro the transformer (doubtful) or excessive current draw (a short). "In rush" current is not your problem. There is not enough capacitance on the Legato to cause that sort of problem. It's more likely a plain old intermittent short, either in the wiring/soldering, or a bad part, such as a cap or transistor.<br /><br />I would install a fuse between the transformer and the Placid to protect it moving forward. Something like a 1A slow-blow. Typically this is not needed, but it will save you from killing boards while you track this down.</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23002:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Trying to troubleshoot an issue but keen to get a response on exactly what the impact of a placid BP overheating is...<br /><br />What parts are likely to fail? Could this cause shorts anywhere?</td></tr></table>2015-08-25T12:29:05-07:002015-08-25T12:29:05-07:00biggsd<table class="content postContainer" width="100%"><tr><td>Trying to troubleshoot an issue but keen to get a response on exactly what the impact of a placid BP overheating is...<br /><br />What parts are likely to fail? Could this cause shorts anywhere?</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid23001:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>PLEASE HELP - its happened again!<br /><br />So, I had the issue I described earlier, and I COMPLETELY REPLACED the Placid board with a brand new one, all working perfectly at home, no problem. Note that I replace the PLACID board but the legato and DAC still the same on that channel.<br /><br />Now I took the DAC into the venue where the event was, turned it on and BANG rectifier blew up again, brand new supply smoked.GRR.<br /><br />It was a perfectly new and hardly used board, with Placid 2.1 so it was the newest one. the only thing that is the same is the Tranny, the Legato and the digital board. Rule out the digital board and we are down to the tranny and the legato on either side of the Placid.<br /><br />Like another user has said, when I have seen this fault in the past it only occurs when a legato is connected. Is there ANY chance that the legato might have been overloaded and overheated before, and then something failed in it or is now a bid dodgy that is intermittently shorting the output of the Placid when it turns on? Causing the inrush current to be too much when its turned on and thereby smoking the rectifier?<br /><br />I really need to fix this this week and I can replace the rectifier but Im afraid it wont fix the problem, please help! I will do anything to get this fixed this week as desperately need it working for my event on Friday. <br /><br />Thanks!<br /><br /><br /><br /><br /></td></tr></table>2015-08-25T12:03:05-07:002015-08-25T12:03:05-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>PLEASE HELP - its happened again!<br /><br />So, I had the issue I described earlier, and I COMPLETELY REPLACED the Placid board with a brand new one, all working perfectly at home, no problem. Note that I replace the PLACID board but the legato and DAC still the same on that channel.<br /><br />Now I took the DAC into the venue where the event was, turned it on and BANG rectifier blew up again, brand new supply smoked.GRR.<br /><br />It was a perfectly new and hardly used board, with Placid 2.1 so it was the newest one. the only thing that is the same is the Tranny, the Legato and the digital board. Rule out the digital board and we are down to the tranny and the legato on either side of the Placid.<br /><br />Like another user has said, when I have seen this fault in the past it only occurs when a legato is connected. Is there ANY chance that the legato might have been overloaded and overheated before, and then something failed in it or is now a bid dodgy that is intermittently shorting the output of the Placid when it turns on? Causing the inrush current to be too much when its turned on and thereby smoking the rectifier?<br /><br />I really need to fix this this week and I can replace the rectifier but Im afraid it wont fix the problem, please help! I will do anything to get this fixed this week as desperately need it working for my event on Friday. <br /><br />Thanks!<br /><br /><br /><br /><br /></td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid22908:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>Yes it normal the negative half draws more current than the positive.<br /><br />I would start by measuring the temperature on the surface of the rectifier when the DAC is operational.<br /><br /><br />Regarding the blown - start by changing the most obvious - the rectifier.</td></tr></table>2015-08-08T06:21:49-07:002015-08-08T06:21:49-07:00avr300<table class="content postContainer" width="100%"><tr><td>Yes it normal the negative half draws more current than the positive.<br /><br />I would start by measuring the temperature on the surface of the rectifier when the DAC is operational.<br /><br /><br />Regarding the blown - start by changing the most obvious - the rectifier.</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid22906:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer_Alt" width="100%"><tr><td>Here is the underside of the board</td></tr></table>2015-08-08T01:01:16-07:002015-08-08T01:01:16-07:00biggsd<table class="content postContainer_Alt" width="100%"><tr><td>Here is the underside of the board</td></tr></table>urn:twistedpearaudio-com:ftPosts:st1:meid22905:1Rectifier Blowing in in new Placid BP after heavy use<table class="content postContainer" width="100%"><tr><td>OK so i purchased a new Placid board and its installed all working perfectly.<br /><br />One thing I have noticed is that the negative side of the legato draws 20ma more than the positive, is this normal?<br />Hence the negative side of the Placid is set higher in terms of CCS, but the shunti is still 50ma<br /><br />So, really keen to fix the failed board so I have a backup, and understand WHY this is happening. Plus ensure it doesnt happen again.<br /><br />I have attached pics of the underside where is shorted and a more hi res pic of the implementation.<br /><br />If someone can help me with:<br />- What parts to test / replace on the failed board<br />- Any other things I can do to the implementation. I have fans on the case but i was thinking to upgrade them.</td></tr></table>2015-08-08T00:58:47-07:002015-08-08T00:58:47-07:00biggsd<table class="content postContainer" width="100%"><tr><td>OK so i purchased a new Placid board and its installed all working perfectly.<br /><br />One thing I have noticed is that the negative side of the legato draws 20ma more than the positive, is this normal?<br />Hence the negative side of the Placid is set higher in terms of CCS, but the shunti is still 50ma<br /><br />So, really keen to fix the failed board so I have a backup, and understand WHY this is happening. Plus ensure it doesnt happen again.<br /><br />I have attached pics of the underside where is shorted and a more hi res pic of the implementation.<br /><br />If someone can help me with:<br />- What parts to test / replace on the failed board<br />- Any other things I can do to the implementation. I have fans on the case but i was thinking to upgrade them.</td></tr></table>