leesteel Posted June 15, 2016 Share Posted June 15, 2016 Fried the diode and another component on the power input of my pcb. would like to know the value of this diode if someone from L6 sees this request. also need to know the part/value is, of I7 that runs between the power input and the negative side of C111 Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted June 15, 2016 Share Posted June 15, 2016 Any surface mount diode of the proper size will work. ( you can tack in a leaded one too) It is only there to prevent negative voltages from getting to the expensive stuff. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 15, 2016 Share Posted June 15, 2016 PIV (peak inverse volt) spec has to be correct, or it will blow again. Current is trying to flow the other way. Take the battery out before plugging into the VDI cable. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted June 15, 2016 Share Posted June 15, 2016 This diode failure is caused by trying to plug in the battery backwards. The diode fails when that happens. It can be replaced with almost any silicon diode. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 15, 2016 Share Posted June 15, 2016 Not quite so in this case,... Typicial diode drop is due to trying to run VDI with battery still inside. But yeah, that too what Charlie said, only way fewer incidents of that. And depending on which diode,.... no, not any diode will do. Quote Link to comment Share on other sites More sharing options...
leesteel Posted June 16, 2016 Author Share Posted June 16, 2016 OK so how about a value. I am going to have to use a standard diode. There are on pads left to reattach a surface mount diode. Also need a value for I7 Quote Link to comment Share on other sites More sharing options...
d1stewart Posted June 30, 2016 Share Posted June 30, 2016 PIV (peak inverse volt) spec has to be correct, or it will blow again. Current is trying to flow the other way. Take the battery out before plugging into the VDI cable. Er... what? Are you saying that if one is plugging in a VDI cable---say, to run to a Helix, or POD HD500---I need to remove the battery box from my Variax 500? If so, that might merit a mention in the manual and maybe a service alert to owners. It's sure not in the currently available Pilot's Guide for the Variax 500/700. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted June 30, 2016 Share Posted June 30, 2016 That is BS. You should not have to remove the battery when using the VDI. I never do. The Diode blows if you ever try to plug in the battery backwards. Specs on that diode should not be critical at all. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 30, 2016 Share Posted June 30, 2016 1) No, it's not BS. It's been the case with early Variax since before I came to Line 6. "The Diode blows if you ever try to plug in the battery backwards"--- 2) Yeah, backwards batteries will do it too. "Specs on that diode should not be critical at all"--- 3) Wrong. Exceeding PIV blows diodes, that's why diodes have a PIV spec in the first place, so that you know not to go beyond that. Pulling batteries when using VDI is even more important with the 700 Electric. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 30, 2016 Share Posted June 30, 2016 Diode is a one way valve. Peak Inverse Voltage (PIV) is the maximum voltage that can be sent in the inverse direction before the diode fails. Too much voltage beyond that, and it overwhelms and breaks down the volt barrier,... and the diode fails. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted June 30, 2016 Share Posted June 30, 2016 The most basic 1 amp diode is 100V PIV. That is way more than enough! Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 30, 2016 Share Posted June 30, 2016 Some basic ones have 75V PIV. But that also assumes volts coming from one side of the diode at a time. Battery AND an XPS or VDI,... at the same time,... volts coming from both sides of the diode, while the diode is on,... poof! Failed diode. Even worse for Schottky and Germanium diodes. It's not going to handle volts from both sides at the same time. Same with the 700 Electric. Quote Link to comment Share on other sites More sharing options...
Charlie_Watt Posted July 1, 2016 Share Posted July 1, 2016 Diodes don't take sides. There is either a forward voltage (diode is conducting) or reverse voltage (diode is off). The reverse voltage rating is typically at least 100V on any general purpose silicon diode. Forward current of 1 Amp is typical and more then enough for that application. You are making much more of what that diode does than necessary. 1 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 1, 2016 Share Posted July 1, 2016 When the diode conducts and you have voltage build up coming the other way in a circuit, while the diode is on (conducting), as in volts from VDI one way and battery volts from the other,... there is an opportunity for the diode to fail. And it usually does. I've seen it happen. Used to do this in school as a test to see how diodes fail. It's why 700 Electric boards were later revised. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 1, 2016 Share Posted July 1, 2016 In a nutshell,... Using battery and VDI at the same time has been a problem on and off in the past. So,... don't do that. Use one or the other at any given time. Quote Link to comment Share on other sites More sharing options...
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