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[fabrizziop]

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[VirosaGITS]

Hi. Recently, one board of my antminer s5 died. The red led on the board won't turn on, and it's cold. Shows up as ----------- on the miner config. I wonder if that's a situation that could be fixed by a reflow?. And, does anyone know what to expect/what to measure on the PCB test points?, like the expected core voltages and so on. Thanks.

Checking core voltage should give you an idea. My dead board has things all over the place, from proper 0.6x volt to 30mV. From how to repair this, i don't know if its doable, its pretty hard. (Maybe RichBC can reply to this in less noob terms)

If its really dead and you tried a different psu, swapping the controller of sides and such, then you don't really risk much doing a reflow, its not impossible that it will bring it back alive, but it did not work for me.

[sobe-it]

You can try, but be careful.... I did a reflow and no change, after a couple times (after cool down) the board started to slightly bubble so i just pulled the chips. From what i have seen is usually its the ldos that fail, or the section in the upper right corner that takes the 12v and boost it to 14v

https://bitcointalk.org/index.php?topic=1196459.0

https://bitcointalk.org/index.php?topic=1211660.0

https://bitcointalk.org/index.php?topic=1062103.0


there are a few more i want to link you to but i will have to keep digging.

[toptek]

give it a shot and follow all he said i did it in a small toaster oven it worked and lasted a while, but i got sold a bad S5, to start with ,they made good on and told me to keep it . what have you got lose but maybe regain your S5 back .

[VirosaGITS]

give it a shot and follow all he said i did it in a small toaster oven it worked and lasted a while, but i got sold a bad S5, to start with ,they made good on and told me to keep it . what have you got lose but maybe regain your S5 back .

Just don't melt the chips, then if it is not successfully revived, the board itself will still have some value in term of chips/salvage parts. Maybe 25 to 50USD, depending on if those Sidehack pods take off or not.

[RichBC]

Is R35 missing for anyone else?.

R35 should be fitted.

Rich

[AJRGale]

i have little experience with these, but to me where that resistor and diode network is, it looks like a low pass filter protection for an input? (please, anyone know better can tell me how wrong i am)

since there is 3 lots there, R180 and R34 to the diodes were taking up the slack of the missing R35, going by the solder pads there its been gone for some time, but the 2 last remaining resistors looks burned out. Odd really with the little signal wire that its running, but the amount of damage there is, i assume its got something to do with voltage control, and not comms?

To repair, you gotta know what that little network is for, i don't own one, so i cant say, cant probe it. Then you got to attempt to, of course rebuild it..

there is what looks to be a clone at the top section of the board, R25 to R29 and R179, and R29 looks to be the match.. in fact it looks as if almost every ASICs have one of these from an output..

[RichBC]

i have little experience with these, but to me where that resistor and diode network is, it looks like a low pass filter protection for an input? (please, anyone know better can tell me how wrong i am)

They are the level shifters for the data signals that pass between the BM1384 chips on each of the nodes. There are 6 signals, R35 is the Clock signal so it's quite important. 

Rich

[RichBC]

i have little experience with these, but to me where that resistor and diode network is, it looks like a low pass filter protection for an input? (please, anyone know better can tell me how wrong i am)

They are the level shifters for the data signals that pass between the BM1384 chips on each of the nodes. There are 6 signals, R35 is the Clock signal so it's quite important. 

Rich

I checked with more detail. It seems that R34, R35 and R180 are all connected to the same trace R32 and R31 are. In my board, the trace broke at R35 so it doesn't even get to R180. Will need to ghetto solder them external resistors both with a piece of wire.

Could this be a common issue that plagues the Antminer S5?.

The resistors are pull ups to the 1.8V IO voltage on the Node, as part of the level shift between stages. If there are multiple failed parts it is probably caused by another failure on that stage?

Rich

[RichBC]

The wires are connected to R35 and R180, with 620 + 68 ohm (in series) each. The repair costed me 7$ at a local cell phone repair store.

Great that it works, but not sure I would want them repairing my Cell Phone.... 

Rich