Well just a suggestion about creating a new board... you know that the A2 chip set has identical pin layouts.. so if we want to get serious about mining then we could source our chips directly from Innosilicon and save a bundle.
I inquired with them and a single A1 chips is around $45. So if you go with your own created boards and maybe a mineral oil (or immerssion)... and then locate yourself beside a hydro-electric damn, then you have a good chance at being profitiable with Bitcoin mining!
Ants, even the power hungry S1's, are very profitable for me. Even without the current rise in BTC value my 9-Ant pharm is 3/4 'paid off' in just under 3 month of running. I used the quotes because tonight I'll be using most of the BTC earned to order a s2 from Bitmine... |
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AMT_Miners, ISAWHIM and anyone else interested in best practices when it comes to pcb layout & EMC issues - here is link to one of the best references I've come across yet. http://www.emcfastpass.com/rightfirsttime/Not is only how-to but also strong on the WHY. Do you think you would be able to design a new board using the reference design available from Bitmine? You just need to increase the number of A1 chips from two to four (or even eight). Could I using that as a starting point - and being a reference design that is all it is - certainly. Do I have the time needed - hell no. You are looking at at least 2-3 weeks solid spent checking/specing the parts and then doing board layout. Between Opium, ISAWHIM and me we probably have most everything covered to do it I'd think. Our company is booked solid until next Feb and part of it involves orders for 3 next-gen system I've designed. Taking things off the bench and starting the 1st prototype of it next week when a few structure parts come in. That and why re-invent the wheel? BMch and AMT have already done what is needed to take the A1 from testbed to a real miner, they just seem to have fallen down on implementing it right. That should be changing. Being that the ref board on Github is all I have to go on so far it strikes me that at least 1 thing is missing from it - coms to the Vdd regulator for tweaking the voltage. Also, where does 5VMAS that feeds the regulator chip come from? Don't see any 5v lines called out on the I/O connectors... |
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AMT_Miners, ISAWHIM and anyone else interested in best practices when it comes to pcb layout & EMC issues - here is link to one of the best references I've come across yet. http://www.emcfastpass.com/rightfirsttime/Not is only how-to but also strong on the WHY. |
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It is possible to get the driver to do this. It is one reason I am requesting docs on the driver. If it is using the standard A1 driver then I would just need to modify it. But I am largely working blind with the driver side now. I have been reading up a bit on driver coding as its not my strength. But I got enough of a handle on it I think I can make it run a delay just long enough for the hardware to initialize properly.
How much have you read up on the A1's actual chip coms? I see in the pdf on github there are a lot of chip-level detect/response options. Out of my range on the software coding end there but see a lot of possibilities in the command list... |
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i got an invoice this morning. havent been through the several pages on this thread to see why. why the invoice?
So far no word on that. Rather like the Cheshire Cat no? |
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Is it possible to implement looking for a simple 'I'm alive' signal from the cards for a few seconds to give them a chance to wake up before starting the device present scan? Kinda a reverse PWR_OK function. Or quick & dirty, just delay the scan for a few seconds after power up? Delay the start of cgminer a few sec to let other background devices come alive first? Actually, raises the question of how the power-up Vdd voltage is set. Hopefully it is hard wired to start at a safe voltage until told otherwise - right?... What happens if +12v is applied without backplane communications? A while ago on BFL's blog it was said the Monarchs start up at Turbo voltages until coms are established. Power input is around 1.5x normal during that time... Dunna know if they addressed that or if the chips just needs a kick in the butt to start up. Sound familiar (kick) from the A1 dev thread ISA?  |
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Mmm. Guess we gave them somethings to chew on for a while  Yes I noticed the large negative ground-shielding, surrounded by large positive plates, which is the essence of an electrical capacitor. (Two plates of opposite polarity, separated by a layer of non-conductive medium.) Might explain the electrical run-off that is causing the VR to bump-up in time, which leads to ever-increasing voltage, leading to more capacitance, leading to more increasing voltage. I am just not sure why one board does this, over another board, being all of the same design. With exception to the issue of substituted parts that may be leading to the failure. So hard to see some of the numbers of the smaller components. <snip> Close enough fer gument work as they say Welcome to the world of power RF design. Specifically what is called 'lumped component' effects. Refers to the various interactions that go on at frequencies starting around 500mHz and up. While the switching regulators probably only run around 100-150kHz their response bandwidth is several mHz. More to the point the rise/fall times of the waveforms produced will be on the order of only a few ns (100's of mHz). Those 2 things put us in the be-very-careful zone when the loads (ASIC's) are spread around as they are. Remember, we are not talking about an infinitely stiff pure DC source drive a purely resistive load. That DC source WILL have a high frequency component to it and it is driving a very high frequency pulsed load. (What is the clock freq anyway?) Very easy for local run-away voltages to crop up from resonances. Think of it as ringing with a fair bit of power behind it. If you do ham or CB radio is called excessive SWR and leads to a blown transmitter... Is why local bypassing at the chips is needed. Putting bigger caps close to the buck inductors certainly helps give a stiff power source at that point but it is what happens between there and the chip that can cause trouble. And - where is the Vdd sensed for the regulator? At the big caps or close to the furthest away chips (kinda remote-sensing)? All things considered, best is at the main big caps. Soo many questions on this... |
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Mmm. Guess we gave them somethings to chew on for a while |
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Yes very close. Is thermal paste conductive?
For the vast majority on the market, not at the voltages used on these. Possibly a bit capcitive but that is more an issue if it is smeared across bare connections. Possibly corrosive to aluminum though if containing silver. That would take a while to get the point of corrosion, some of the pastes did contain silver, like the Arctic Silver 5 thermal paste. In general, despite it having silver we have not found that as the main reason for the problems. The main problem lies in the amount of copper in the board itself, which we had not discovered until recently. Amount of copper? As in the cladding being to thin for the currents/thermal loads involved perhaps? |
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AMT_Miners: If you want a board physical design review pm me. I've been involved in power systems not to mention a helluva lot of other circuit design for almost 40 years...
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Yes very close. Is thermal paste conductive?
For the vast majority on the market, not at the voltages used on these. Possibly a bit capacitive but that is more an issue if it is smeared across bare connections. Possibly corrosive to aluminum though if containing silver. |
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 Here is the back side.... doesn't appear to have any layer improperly exposed. At least that bit of boards looks covered. Remember they dis say that many - not all boards had the uncovered via fault. Center left is a major no-no that thu-hole for screws is way way too close to those covered vias either side of it. Pressure IS going to cause faults in the screen layer. |
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Well if they were indeed shorting... that problem would have been identified with initial testing.
Don't tell me that these systems where shipped without testing??!
If the layer where improperly exposed, then one could have easily made temporary fix by taping the exposed parts.
Depends. Initially the thermal pad may have kept may/most from shorting out so any initial test would have passed. Unless there were pointy bits that is. After that things moving from thermal cycling and just time will be enough for it pierce the pads. It may well explain the delayed-death syndrome we have been seeing... Yes Mylar tape would fix that. And again care must be taken to allow for that added gap produced. So far I would not count on that as it strikes me that whoever designed/reviewed the design of all this have zero-experience at it. |
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What are you saying here? The manufacturer had exposed vias that assumes the use of a thermal transfer pad.... was a thermal transfer pad used?
No I take it as the signal and power vias were left uncovered leading to them shorting. Only the thermal xfr vias should be bare. And - due to the thickness of the green/red screen layer that is supposed to seal the boards one damn well better make sure that something bridges the resulting gap between the sinks and the thermal vias. |
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<snip>
Yea, those seem to be the largest source of heat, once the cards stop functioning. May be the coils insulation failing. Those too, it seems, are not real flush-mounted to the board. There are exposed heat-pads under them, on the heat-sink side. However, the varnish actually raises the heat-sink from direct contact to the metal at all. (Looks like the heat-sinks should be machined to match the pads, but they are not. They are essentially using the heat-sink compound to "fill the gap" between the exposed heat-pad and the heat-sink, which is not the function of thermal grease. Thermal grease is designed to fill the microscopic gaps, not gaps of zero-contact. Which is where heat-pads are designed to function.)
<snip>
Did notice another thing that bugs me a little, about the cards... The PCB sticks-out beyond the heat-sinks, by a fraction of a MM... This bugs me because the frame mounts firmly to the cards by the heat-sink, which has a metal-edge pressing hard against the PCB itself. This too stresses the PCB, and I am not 100% sure that the inner layers may or may not have any stray "copper traces" near the edges, which are in direct contact with the metal frame. Mostly, my concern is the compression of the PCB, as the aluminum expands and contracts from the heat. (This also being a concern due to the solid screw mounting which is firmly holding the non-expanding fiberglass PCB to the expanding alu<snip>
Ja the buck inductors are supposed to be in contact with *something* to suck out some of the waste heat. Along those lines, got a part number on them? With all that is turning up would be a good idea to make sure they are running under their max dc-current rating. If over it then the cores will saturate and say goodbye to regulation. On traces near the edges: If whoever laid out the boards knows anything about EMC basics then all traces will be at least 2x the board thickness away from the edges to close near-field loops. Any closer and emissions goes through the roof from the loops becoming true radiated EMI. Um, that rather raises a point - have these been EMC tested at all? Not sure if miners fall under FCC much less EU exempted equipment... |
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Hmm I just got an email from AMT....I got an invoice...balance paid in full and all that. Looks like they might be restructuring their records keeping process.....least to cover things. Wonder if the company has changed hands or something.
I would hope the next step is to get us all the working hardware we ordered for the invoiced amounts. OR if they are being forced into honoring the MPP that would be good too. At this point tho I am doubtful of any refund option or RMA. I just want working hardware I can hash with. I am stuck with what is a 500Ghs miner when I should have been hashing at 2.4Ths with my two miners. Quite a gap. Well hopefully the next email is that I am getting a product shipped for me if I got an invoice. (even though I got one already from them once before)
Since I had never gotten one I had requested my Invoice from Alyssa a few weeks ago when AMT was replying. Got it the same day. Dates are correct as is amount they received from me, payment method was wrong. Says was wire xfr but was personal check. |
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Can always just solder a length of twisted-pair out to somewhere convenient outside the shroud from the chip cap.
A shot in the dark - is the flakely board one of the ones with the 10k resistors in place of caps? If so could be that the remaining caps are starting to fail from excessive ripple currents.
Buck inductor temps are something I've never been comfortable with for various reasons. They are actually rated to run pretty bloody hot with max ratings often 140C or more. At least they are one of the few things that heat does not really affect until insulation failure. If you can keep a finger on it without branding yerself then it's good. I'd worry more about the solder connections to them failing from temp cycling and the heat getting to nearby components.
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Don't suppose your meter has hi-lo hold function does it? If does you can wire leads across one of the local chip caps and record the core voltage and see if it changes...
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