Cheap and simple repair of S7 hash board

[sidehack]

9.7V would be enough to start at about 500MHz, but certainly not stock.

[1714787428]

1714787428

[1714787428]

1714787428

[1714787428]

1714787428

[1714787428]

1714787428

[1714787428]

1714787428

[NotFuzzyWarm]

Query: Has anyone checked to see exactly what causes the failures on these boards? Specifically, could it be from a chip resistor in the VRM circuit failing?

Reason I ask is that Bourns just put out a white paper on their sulfur-resistant resistor packages and in it they specifically mention China and India as areas where sulfur pollution (in the air) is a problem. Sulfur in the air attacks a portion of the silver plating connecting the internal resistance element with the chip terminals and can lead to the resistor cracking/simply opening. Considering that miners are often tested for a fair bit of time before shipping one has to wonder if they were ran during high-pollution alert days...

[sidehack]

I would guess it's not a resistor in the VRM circuit, given that it appears the DPOT is starting to midpoint and the buck is operating properly. The PIC's VDD actually comes straight off the 3.3V line on the 18-cable to the controller, so if it was a volt issue toasting the PIC it'd also affect the DPOT and controller board.

[NotFuzzyWarm]

I was thinking more along the lines of what would happen if one of the fixed resistors in the DPOT reference voltage divider went bad. That would change its output. Still, was just a shot in the dark.

So problem is the PIC itself blowing?

[sidehack]

Based on what the folks in this thread have said, it looks like the PIC never updates the DPOT's setpoint. If it's a resistor going out doing that, it'd almost have to be one of the 4.7K pullup resistors on the I2C lines.

[xxcsu]

Any idea how to apply this "Cheap and simple repair " for S7 batch 1 blades ? I have a few none working blades from S7 batch 1 . All of those blades have the same problem ,If the board plugged in itself , then  48 or less ASIC reported , status is " ooooooo " x48, temp reading working , temp is changing if i switch the frequency lower or higher . If the bad board is plugged in with the another two , then asic# reading is 30 status is "--------" x30, and the temp is not changing at all... Visually inspected the boards , no burning sings . Switched cables , power supply , control board , reset the miner , but no luck ...  the last board went out yesterday , just removed the miner from the rack to replace with one of my new s9 , moved the miner around a little bit , then plugged back on the new place and one board stopped hashing . I run out from the spare hashing boards for batch 1 , time to find a way to repair them somehow if it can be done . Im done a couple of times the "Cheap and simple repair of S7 hash board " with 70-75% success on the 135 ASIC version board .

[sidehack]

This fix does not apply to S7 Batch 1 boards, since it deals with the board's voltage regulator and there is none on the 54-chip boards, just the 45-chip boards from later batches.

[xxcsu]

i understand that , thank You . So there is no way to fix the 54-chip boards?

[xxcsu]

set back the frequency to 450 , another 2 boards is hashing fine , the " bad one " asic status is changing from " oooooooo oooooooo oooooooo oooooo " to " xxxxxxxx xxxxxxxx xxxxxxxx xxxxxx " back and forth in every few minutes , no hashing power from that board , temp and asic count not changing . Another bad batch 1 board from different miner doing the same thing ...

[opmac]

My S7 and also my friend's S7 stopped hashing many times, even when boards arrived from RMA, so I decided to stop expensive sending of boards to Bitmain and wait so long without mining. This mod is only suitable for 135 chips version.

After repair I am able to adjust S7 very efficient, my B8 runs at 600MHz (4.05TH/s) with 0.22W/GHs DC, so it is around 0.235W/GHs at the wall.

Repair is very simple, every board I'v seen had malfunctioning or not working PIC microcontroller adjusting voltage for chips, so I decide to override this by 50k potentiometer. Now I can adjust voltage for each board manually.

This is original board without fix. You need to connect potentiometer between U2--R17 connection and GND which can be found on C76.

http://pantin.cz/20160209_155344.jpg

Firstly, use silicone or any other suitable glue to glue potentiometer to the board. After it dries out, you can solder its pins to R17 and C76.

http://www.pantin.cz/20160401_095409.jpg

Once you are done, you can use small screwdriver and turning clockwise potentiometer will adjust lowest voltage, about 9.3V which should be enough to start miner at 500MHz.
You can adjust voltage for each board even when miner is running and check instantly number of HW errors during operation.


I hope it will help you. My opinion is that PIC malfunction is intentional from Bitmain to lower diff after RMA period.

Just want to confirm that this method worked for me. I finally got off my lazy ass and fix my s7

It took about 5 mins total. LOL!!!

Thanks for the fix method.

How did you figure this out in the first place? 

[isoneguy]

does this fix work for boards that are only showing 7 or 8 chips?

[RadekG]

does this fix work for boards that are only showing 7 or 8 chips?

Just try it.

[isoneguy]

Just try it.

It's no fun without a warranty to void.

[ventas3mil]

Thanks for the data brother. You win my admiration

I have an S7 antminer, Batch10 works at 4.73TH/s and 700mhz PSU Original Bitmain.
A hash board stopped working and I pulled it out to check.

My failures:
A) Asic Status: (---- ---- ---- ----)
B) GH / S: 0

Test 1:
I made the modification you suggest, leaving the chip u2, 50K common trimmer.

Result:
Max 650 freq,
Asic Status: (000 00000 00000)
GH / S: 0
, But Instability. After one hour Asic Status again (----- ----- ---- -----)

Test 2:
Action: remove the u2 chip.
Result:
Max 650 freq,
Asic Status 000 00000 0000, stable after one hour.
But GH / S: 0

Summary:
The modification of test 2, solves the Asic Status (--- --- ---) but in my case it does not work, it continues at 0 GH / s

If you know that it should be checked additionally to make the hash board 100% operational and enable the work in GH / s, it would be excellent.

Thank you.

[sidehack]

Did you make sure the voltage was set to at least around 10.4-10.5V? That's about what it'll take for 700MHz to mine.

[ventas3mil]

Did you make sure the voltage was set to at least around 10.4-10.5V? That's about what it'll take for 700MHz to mine.

No, because the test was 100% manual, without multimeter, I validated that at 700mhz it does not change the Asic status when turning the trimmer.

It begins to detect the work of the maximum trimmer in 650 mhz.

If you can take a photo of the voltage test with the multimeter, I could do it also and raise the result that I get.

[sidehack]

That's certainly weird. 650MHz should start working around 10V, but a proper pot should be able to crank it up past 11V.

If the PIC is shot, you could replace just the PIC and program it to whatever voltage you want. I've got a thread on S7 hacking that talks about how to do that. I've not actually done this fix, but I pulled from some of the research done for the PIC solution.

[gnomominer]

Hi I've been trying to follow this thread to see if I can fix my problem. All well and then the situation with one of the boars is the following:
1) ASIC status 30
2) temp 46
3) symbols for the Asic status -----------------------

Ever since this happened I mine at 3Ghs and not at full capacity anymore with my Antminer S7. I got it used but worked fine for a month or so.

I've tried to reboot both physically and from the software panel. Checked and changed power connectors but no results. Only thing I did not do was to upload new firmware, as it seems to have already the newest version available and the other two boards works.

Do you think that your solution could be tried out? How can I find out how many chip I have on the board?

Also how do I test for the voltage? Or adjust it while the board is running?

Sorry but I'm not really an hardware guru

Thanks

[jamesb777]

Has anyone attempted a similar mod on an S9 antminer?  I have a failed hash board that's getting no voltage past the inductor (from what I'm assuming is a faulty PIC controller).  This looks like a very promising fix.

[demianra]

Hi all a few days ago i saw that D24 it´s a 40V 1A schottky that part works for you, i have some boards with this diode broken.