Re: GridSeed 5-chip USB miner voltage mod

For some reason my units are dropping like flies. In the past 24hr three units have burned the USB ferrite bead. I can't seem to make any connections for why this is happening, one unit has VOLT mod 1; two bridges, has been running for a month. The other two

have "R-52 or R139" mod with 47k and 50k resistor, also been running stable for a month. None of the units shared the same USB hub so I crossed that off the list of possible failures, two shared the same power supply but the ferrite bead that burned is for the USB hense 5volts so not sure if that would have mattered. I am lost finding any correlations between the units that failed, possibly just a coincidence or a weak part, but its suspicious that 3 have failed in the past 24. We shall see, now have to order new parts and wait to get them back online.

That sucks. Very strange also. 3 different mods, 2 different power supplies. Same part blown on 3 boards. Tell us more about the power supplies you have.

Both power supplies are the 30amp LED power supplies, I have checked with a multimeter the barrel plugs for each unit, and steady 12.4 volts. The ferrite bead is the one next to the USB plug on the board labeled FB26. Does anyone know if FB25 is the same as FB26, I would like to try to desolder FB25 from one of them and plug it into FB26 to see if it starts hashing again before I order parts. Are ferrite beads directional or can they be placed any which way? Any tips on a way to check to see if they will hash without the bead, IE jump the pads just to check if they will hash? Thanks in advance for replies, I am frustrated about the death of 3 and am worried it may domino to the rest if it is something else not just a coincidence.

First check a continuity test on ur board between 12+ and 12- and USB power +/- if you see any short between them , there will be no point to solder another FB, because it will blow again. If u do find a short between any of ur 12v and 5v rail , report back. I assume u own a basic multimeter .

PS: because of ur blown FB you will not be able to use USB socket pin to check the continuity . best thing probably to check from one of the pad for BLOWN FB to ground.

Could you explain a little further how to check the power.

Make sure ur gridseed is not powered on. Take off the 12v plug from gridseed. Set ur voltmeter to continuity test mod. Put the red prob from volt meter to blown FB pad(one at a time) and put your black prob to fan's black cable. Does it make any sance to u?

You should get 2 result. Both should indicate no continuity at all.

Alright so I salvaged one unit by taking FB25 from the other burnt out board and using it for FB26 in the first. At first it didn't start hashing again until I hit the reset button and then it worked. I did not see any shorts using the multimeter to check on that board so hopefully it will continue to work. The other board has a short between FB23-24 shorted to FB27, not intirely sure where it is shorted but cross checking with a good unit, those are not suposto be connected. I am going to have to look through the brd file to see where a short could happen between those pads. The third one I also found no shorts like the first, but am going to have to wait to get the new ferrite beads in before I can try that one again. I think the 2nd one will just end up bricked unless I can locate the short or someone else chimes in that has had that problem and figured out a fix for it. Thanks for the replies and help, and hopefully when I get the proper parts I can get the third back up and hopefully no more decide to shit the bed.