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You can't steal money with crypto. Small wonder the banksters hate it.
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As lightfoot said, older electric dryers and ovens often used to improperly use the ground to give 110v to timer motors & light bulbs. It was only allowed by some local electric codes because said loads draw very little current so *in theory* the combined neutral/chassis ground *should* have very little voltage difference on it referenced to any nearby water pipes or any other grounded metal.
The real fun part is what happens if/when the ground opens. Let's say you didn't screw down the ground properly in the circuit box and you had a 120v motor in the appliance connecting to one hot leg and the ground (which is also attached to the frame of the washing machine for safety). Now 5 years later the ground opens. Maybe thermal expansion loosened it, maybe the small amount of current being used by the motor browned the wires a bit more each day till current would not flow. This happens. You now have a situation where the power goes from the hot leg, through the timer motor in the appliance, and dead-ends at the ground as there is no path back to neutral. Thus the whole dryer metal box is now "hot" with the current from the dryer motor trying to find a place to go to neutral. Now you touch it, while standing in that wet puddle next to the washing machine. You have now become the path to "ground". And since 100ma at 120v is enough to kill a person you had better hope that motor can pass less than 100ma. As shown in the chart, shock is relatively more severe as the current rises. For currents above 10 milliamps, muscular contractions are so strong that the victim cannot let go of the wire that is shocking him. At values as low as 20 milliamps, breathing becomes labored, finally ceasing completely even at values below 75 milliamps.
(Electrical safety, the fatal current (1987), Ohio State. Retrieved from https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html) That is the problem. If the motor went back to the breaker panel on a neutral and the neutral opened then the frame of the dryer would not be hot as it is connected to neutral and not the motor. If the ground opened up then the frame of the dryer would still not be hot as nothing is connected to it (however if a ground fault developed say in the dryer motor the frame could become hot which is why you ground it). The voltage differential is one thing, but if the frame ground is expected to carry a load and the ground wire becomes disconnected you basically have a hot stove waiting for people to touch it. Interesting stuff. |
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yeah but last I looked on my panel both common and ground connect to same bar.
so what's the difference?
The reason there is a common on 240 volt dryer plugs is due to some old stupidity in the dryer market. Way back in the day dryer timer motors were simple 110v motors that would run the clockwork that makes up the dryer timer. However the dryers were sourced with two wire plus ground 220 (240) volt lines. So the hot (hah!) solution to the problem was to wire the timer, light, things like that up to one leg of the 240 and ground. That gets you a nice 120v. However this is WRONG! It means that ground is carrying current during normal operation which it should never do. Thus the solution was to run a discrete wire to neutral alongside the ground wire to handle the 120 volt hotel loads on the dryer. The other solution would be to include a 240-120 volt transformer (a small one) in the appliance, but that would raise construction costs by a dime and we can't have that.... These days, as dryers and such are electronic, the switching supplies that run the electronics can take either 240 or 120 so the third wire is not really needed anymore. Technology marches on but the 4 wire outlet remains. And yes, they both terminate at the breaker box in the same location. Ground in a house is the common busbar which is usually bonded to a nice pipe or grounding rod going deep into the center of the earth. |
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Meantime I was able to trace down the heat a bit more closely. Looks like the PIIC chip next to that oddball one. Which makes more sense from a heat point of view. Working on the board that sort of works: Oddly enough it does seem to have a bit of a problem with one of the chips (61). Need to map out the board and figure out how Inno counted the chips, could be on either end of the board. Feb 14 18:19:23 InnoMiner cgminer[1306]: hub_cmd_read_register spi crc error !
Feb 14 18:19:23 InnoMiner cgminer[1306]: failed to read temperature for chain5 chip61
Feb 14 18:19:23 InnoMiner cgminer[1306]: [chain5 temp]
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 1: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 2: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 3: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 4: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 5: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 6: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 7: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 8: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 9: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 10: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 11: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 12: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 13: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 14: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 15: 26
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 16: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 17: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 18: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 19: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 20: 25
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 21: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 22: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 23: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 24: 33
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 25: 33
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 26: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 27: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 28: 25
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 29: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 30: 32
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 31: 33
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 32: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 33: 26
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 34: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 35: 32
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 36: 33
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 37: 34
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 38: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 39: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 40: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 41: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 42: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 43: 27
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 44: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 45: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 46: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 47: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 48: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 49: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 50: 31
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 51: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 52: 24
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 53: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 54: 29
18:19:23 InnoMiner cgminer[1306]: chip 55: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 56: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 57: 28
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 58: 29
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 59: 30
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 60: 32
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 61: 392
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 62: 0
Feb 14 18:19:23 InnoMiner cgminer[1306]: chip 63: 0
I'm also figuring out the bit about the power supplies: It's not that the bigger supplies sag or have ripple it's that the board seems to want to see voltage sag to 11v in order to power up. The corsair is dropping voltage under load which seems to be what gets the board going. Weird. |
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[breaking character: I had written a whole JJG-style WoT 'comedic' post about Valentines Day, and when I realized, "You know Bob, maybe when you start writing five paragraphs about keeping your assholes clean, maybe it's best you just delete the whole thing, and go back to bed..."]
Thank you Bob. Merited. |
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So I've had a few requests to fix broken Dragonmint miners. These are.... interesting units and the boards seem to fail a fair bit. As usual there is little to no documentation on the hardware itself, so in order to fix it you kind of have to reverse-engineer the thing. What fun....
First up is to take a look at non-working boards and see what they do. Since we can't talk to them on the spi bus we have to use other tools. In my case I like to start with a watts up power meter on the supply (to monitor how much the board is pulling and when) and an infrared camera to see exactly what is warming up/pulling heat/shorted on the board.
To a fault, the first three bad boards exhibit the same symptoms: They start out pulling pretty much no current, then pull about 60-120 watts of current for a few seconds, then it drops back to zero. This correlates with the logs from the miner trying to initialize the bus and get it going. On a working board it will go to 120, then 250, then whatever the watts the board is tuned for (in the lowest power setting case around 355 watts).
Second was to take IR pictures of the bad boards. And I spotted something pretty quickly: When the board started up one chip on the control circuit got very hot, then the heat went away once the power draw dropped to zero. Like clockwork. I focused in on the chip and found it's an 8 pin SOIC chip with a part number of KBA6F1806
on two of the boards and KBA6F1752 on the third. Pin 8 goes to ground, two pins go to an RC circuit, and one pin goes to the crystal oscillator.
It doesn't seem to be a FET driver, I'm wondering if it is a scratchpad memory for the main processor circuit. However I haven't found anyhting on it, anyone know what it is? If it's overheating then we may have an answer to the problem: That chip goes bad and the board is dead.
Currently I am cooling down a working board in the fridge to see if that chip warms up when the board is first communicated with. On a hashing board it does not show any sign of excessive heat but at that point the copper planes in the board are conducting heat pretty uniformly.
Thoughts on what that chip might be? One way to test my theory is to remove the chip from the good board and swap one of the suspect chips in. Got to be something :-)
another board
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Honestly: How many dead are we supposed to have tomorrow?
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Still it's running way behind that original chart we had up here last week.
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Resurrecting a dead thread: I got one of these Dragonminers in for repair, well actually it is a pile of T1 boards that are shot. Doesn't seem like there is much documentation on *how* to troubleshoot them so off we go....
I'll probably open a separate thread but for starters:
1) Don't get the latest firmware: This one has the Innosillicon firmware on it and while it is pretty there is no way to log into the console (dr4g0nhash does not work) and worse yet the logs cannot be seen from the web console. UG!
2) These are finicky as fuck in terms of power. I have one working board that oddly enough does different things with different power supplies:
On a Bitmain 1600 watt power supply the board will start up, pull up to 200 watts of power (measured at the wall) and will then shut down to 0 watts, then up to 200, then down. Ok, board is bad.
Except it is not: If I use one of my old Corsair CX750M supplies it will come up, climb to 550 watts and start hashing. Of course it overloads the small PCIe wires on the Corsair and the voltage at the miner has dropped to 11.2 volts, but it does work.
Tried my bench power supplies: HP 750 watt server supplies. Same symptom as the Bitmain one. Note both of these supplies work perfectly on my Antimer S9 test units for weeks on end. And the voltage never sags below 12.0 volts.
Even odder: If I plug two PCIe plugs in from the Corsair it works. If it's working and I plug the third wire into the HP supply it will shut down.
Even odder: If I plug in two PCIe plugs from the Corsair and one from another CX500 it will still work.
Even *odder*: If I plug in one PCIe from the Corsair 750, one from the 500, and one from the HP supply it *will* work and current will be balanced between the three supplies.
I'm wondering if maybe these boards are highly sensitive to some sort of ripple in the DC supply. It's not the DC voltage, the Corsairs sag like old boobs but it's something else in the newer and much better supplies.
Oh well. Tuning is done and board is stable at 4.0th in max economy mode, 60c temps.
The other dead boards do a somewhat similar thing: They come up, pull up to 60 watts, then crash to zero. I used my IR camera on them outside the box and I think I see which chips are dead. So I may be able to fix those.
Edit: After running the "tuning" it's at 380 watts for the hashing board for 4.1th output. Not too bad, also it will now run with the 750 watt HP supply. Something was going weird during the auto-tuning....
Oh I'm running the t1_20190311_114300 version. Very pretty but stupid.
Edit: Fuzzing found the logs at /logs. Nice they left it in, wonder what else is on there.
C
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"The land of the free".
Hm. Same government that now uses the FBI and DOJ to reward and punish people based on political affiliation and "pull". What can go wrong with that? |
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The problem with private planes are not the planes themselves, but you need to always fly with a full tank of gas all the time.
Depends on weight and balance calculations. :-) |
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Think "private airplane". I so want one, but such a bad idea.
That's a weird one to me. There are so many owners desperate to make their millstone pay that you'll forever have the entire market at your beck and call to hire. You'll also get the latest and greatest one without fail. Other than the convenience factor to obscure airports a lot of them look pretty goddamn pokey to me. I'd rather have an Etihad apartment and force the butler to pluck my clinkers while another one sucks the fungus off my toes and gobs it back on to my cheese board. Well flying is as fun as hell. And yes you can go to all sorts of odd places. I remember flying out to Catalina island once to grab a buffalo burger on the mountainside. So much better than screwing with ferries. |
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Boats are really a hole in the water. Go for it if you really love fishing. I always buy a used car let someone else take the depreciation hit.
There are worse things than boats. Think "private airplane". I so want one, but such a bad idea. Same for used cars. Never owned a new one. |
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The Washington Post has a very well done article on it. I find it hilarious, wonder what backdoors are in all the "cloud" providers.... |
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Damn, we're stuck at $10,200.
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I wonder when the great switch-over will occur on this forum:
The point at which we cease to say Bitcoin is going "up" in value and instead comment on how Fiat is going "down" in value.
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And to think these chuckleheads are securing the US currency. Kind of makes you wish there was a more stable and objective store of value out there. But where.... |
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so that gnews.org site
is that a falun gong propaganda organ or what?
pretty fucking weird
I really don't see it has anything to do with Falun Gong. Someone did mention that as a connection though recently. It's this guy mostly https://en.wikipedia.org/wiki/Guo_Wengui a cooky businessman critic of the commie regime. There are grains of truth in whatever Lambie quoted earlier, but I can't be bothered to opine more sorry because it's all essentially unknowable stuff and I'm sick of that. Epoch Times is the Falun Gong house organ. God I love to say organ in conjunction with politics.... |
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