Quote from: AMT_miners on August 11, 2014, 10:41:12 PM

Quote from: IMET on August 11, 2014, 01:29:18 PM

Quote from: NotFuzzyWarm on August 11, 2014, 07:00:58 AM

Quote from: IMET on August 11, 2014, 03:30:21 AM

Application of thermal paste and mechanical assembly including mounting boards to heatsinks was not Imet's responsibility. All soldering meets IPC class 2 and inspection was done by trained personal. Everything was in order when delivered to AMT. The likely cause of your boards not working is overheat. The heatsinks used on the top of the ASICS are not adequate to dissipate the required 30 percent.

Yes the top sinks were woefully under sized. However, bet the rig you posted as running fine has the same tiny sinks, no?
Just that the final flaming nails in the coffin are the missing thermal bumps on back side of the board that are supposed to complete the thermal contact path to the main heat sink. I refer you to my previous post on this https://bitcointalk.org/index.php?topic=569769.msg7610781#msg7610781

I have sample boards ranging from no thermal bumps at all to most all there. On average I see what is shown in the above post - most missing meaning that there is no way in hell to make decent contact with the main heat sink as the few bumps present act as jacks raising the board up from the sink. Thermal compound no matter how carefully applied (or drunkenly slathered on) will not compensate for the 8mil gap. So much for the 70% of heat flow path.

AMT was not responsible for those bumps. The CM was. If they were not explicitly called out in the BOM from AMT/Bitmine (my copy makes no mention of them nor having filled thermal vias) then either have none or all of them. Period. If you have ever worked with power devices before you *have* to had known that. Given that some/many bumps are there tells me you knew about the thermal loads the A1 has. After that Roll Eyes

Then there is the dpot chip substitution without regard to the core voltage divider reference circuit it controls... Ohm's Law applied to parallel resistances anyone? Frankly, aside from the legal who-did or didn't do-what points, this is all just stomping around in the rotting carcase of a long beaten to death horse.

No, the rig that I posted did not have the tiny sinks. I built my own prototype and measured the ASICS with a thermocouple. I then redid the thermals and mechanicals. The bumps that you describe are not intentional. They are created when solder flows through the thermal vias and cannot be controlled. There are ways to get good thermal contact with and without the bumps. Lastly, I know nothing about a dpot substitution. We installed what was on the parts list supplied.

Tom on these threads you need to stick to your story. Some of these guys are already like rich and have nothing better to do than follow threads really closely. Focus on the following Tom, then verify it for yourself if you haven't figured it out already.

IMET failed to fill the thermal via's in the asics correctly, period. The .5 oz copper selected for all the boards (let's gain on the margins boys) charged at quick turn pricing didn't help either. Lack of filling the via's was related to either the amount used or the there lack of/or quality of solder they used as well as lack of know how. This first came from a few different pro's in the industry and was later verified to us by those that same guys which produce the damn asics after examining several of IMET's (off the line) boards which we had kept for these specific purposes. Despite the boards not working, IMET continued to run them because they lead us to believe that these boards could be fixed, because every other fucking day when we brought up "what are we doing with the bad board guys, we heard "don't worry, lets get a good line going first and then we'll get back them" bullshit bullshit. And when your dealing with angry clients, emails that make you want to just end it all, and trolls that look like fucking santa writing anti-semetic shit with your families info, your just hoping for the best at that point. After 200k had be given, the attitude completely changed and their true colors emerged. When they realized their mistake, they did not come clean with it, they proposed other bullshit costly options but mostly suggested we order brand new boards for all the pre-exisiting boards built, basically suggesting to scrap 90 miners worth of boards populated with chips which were bad boards. The few boards which were successful were boards created with a lead based solder but had other problems regarding SMT, lots of tombstones and what nut and rework charges.

We were in a desperate situation, already late and we decided to use them because they were free and promised to get everything done within three weeks. That was Feb 8th, btw. AMT trusted IMET and IMET fucked AMT. Helping AMT get their money back from IMET equals refunds.

We're suing IMET, we'll win, and we'll issue refunds, end of story. As to when that's happening, we can't say. Legalities can take a while as you all already know. And if IMET knows what's good for them they'll put their head down, write the check and hold on to their business.

Moral of the story. Don't work with overpriced American SMT's that promise the world, get off your ass and fly to china and do it with people that sleep under their SMT's machines. No that's wrong. Moral of the story, don't accept pre-orders for a machine that doesn't exist which produces a currency out of thin air based on a swiss guy's promised deadline who's relying on a Chinese company that they had no control over. And don't sell to clients which beg for your product over and over for three weeks straight because most likely they'll turn out to be a premeditated nut job that will cause you problems.

Several people have already gotten their miners. It still amazes that only one has come to the forum but what ever. We used an agent to ship, there were some delays in Hong Kong, most miners should be received already or within the next few days or this week.

. Unfortunately, there are so many inaccuracies above. We stand by our work, and there is nothing wrong with the assembled PCBs. As mentioned in an email to you last week, we would consider taking the PCBs built in lieu of payment.

IMET

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