Rank: Member
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Joined: 4/28/2013(UTC) Posts: 55  Location: Auckland Thanks: 1 times
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Yes, the placid and the legato all through the ground screws?
transformers no, but thats normal.
any other tests i can do on the faulty placid?
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Rank: Administration
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Joined: 10/24/2006(UTC)
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Location: Massachusetts, USA
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Do the Placids always fail at a venue, or has it also happened at home? 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  ). 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. . Edited by user Tuesday, May 28, 2019 2:19:58 PM(UTC)
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Rank: Member
Groups: Member
Joined: 4/28/2013(UTC) Posts: 55 Location: Auckland Thanks: 1 times
Was thanked: 1 time(s) in 1 post(s)
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Yes, i have a full test rig now. 2 x desktop power supplies with current limiting. Spare legato board as a load. 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. I have two failed PLACID 2.1 boards. All faulty on + side. Board 1: (and was in the most recent fault with blowing rectifier): 15v no load output no problem. When i add the load, i can maintain 15v BUT only if the shunt current is like 90ma. As soon as i drop the shunt current using the pot to 50ma, the voltage drops to like 10v. vref is 2.48 v. Board 2: it was behaving as above. But then suddenly it went short circuit Current limiting input using power supply. had it up to 1a and it still wants more. I have replaced all of the actives - 7 transistors - including shunt ones - still is showing short circuit. Could IC1 be a fault? What should i replace next? maybe can someone help me with any more tests I can do? Edited by user Saturday, June 1, 2019 11:06:40 AM(UTC)
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