In the meantime I worked on the unit with the lid off. Die 0 seems to be the problem, and sure enough it's shorted according to the output of the dc-dc supply. And the board had 0 ohms on the pins 4,6. So I heated that die to super hot then let it cool down.

The resistances changed. Both on the 4-6 and the dc-dc. Still way too low, but they did change, first evidence a specific die is apparently the cause. Heated it again, back to shorted both places.

So I pulled the die. Real royal bitch. Under it the solder was smeared and there was a bronze ball, which is caused by a really high overtemp. Moral, chip overheated, melted the solder under the die (not the chip) and blew up the board.

So an update: I tried the same trick with a chip that was not bent like a pretzel and the glue would not loosen. Problem is if you push too hard you will rip the plastic underlay that carries all the signals. Too much heat and you lift the balls under the die.

Hm.

Tarkin: The first one was a Neptune, it had the smaller dies. I've only taken apart one Titan, this is it.

Another note: DO NOT BURN THE CONNECTORS. If the ground burns out first the cube will try to find ground through the 10 pin ribbon cable. This will either blow up the cube's die, the controller, or every cube on the controller. I've pretty much got the failure mode mapped out: If the 12v side lifts first the cube shuts down. If the main ground lifts first all of the other cube dies basically have ground dragged through them causing a serious failure.

On a related note, I *HATE* replacing TPS chips. And note that a Rpi can short out the CPU chip which puts 5 and 12 volts on the lines to the TPS chip and FPGA. The resulting damage sucks to repair.

But sank the day today fixing this board. It's up and running, now the owner just needs to send over money for a Rpi, I'll order a new one, and send it on back....

C

It's interesting, and a solid day's worth of work. However thanks to someone sending over a literal taco board, I was able to work the lid off with the right amount of heat without breaking the chip free.

I'll work on it more next weekend, need to see if I can do this on a Neptune, then run the unit without the lid (sinking directly to the dies). Ifso I can try lobotomizing a die and see if I can clear the solder and get a nep to work. If so then I try someone's volunteer.

Well, this is a step forward: I managed to get the top off a die without destroying the carrier.

The dies are larger on this board, I think KNC did two revs:



More interesting, someone tried to fix this board. Bad job!



The secret is to use full board heat, then heat around the side of the chip, then very very gentle pressure to lever up the lid. Bitch on wheels to do, but in this case the top is off.

Hm.

Yes, I have it although I'll have to re-zip. No biggie. Technically it was built off shareware license, thus I don't have a problem putting it somewhere. PM me with a box ID, I can also send over the FTDI config file from one of the units I have here, get FT-Prog.

C

I run my sample cube with a pair of Corsair 750M's, one per side to a single Titan. With that the connector does not overheat at 300/325mhz per die. A single supply with one cable will overheat the Corsair plug. With two cables it will overheat the connector on the Titan due to voltage drop. With two supplies, two cables the voltage is high enough that the amps on the cube's 12v side don't burn pins.

Really, be careful. I have another board here with a burned plug, and a board came in that had the sink torqued down so hard it CRUSHED THE BOARD. I literally am going to have to take some pictures of that. As in ripped open on the bottom :-)

Back to work.

Hm. Wonder who has the keys to the repository. I'd still be suspicious as heck though. :-)

Is there enough interest to try a full recompile on the latest Rpi and/or BBB at this time? I had to put some things down due to commitments, but I could do some tinkering over the next month if there really is.

Meantime bunch of things to work on, back to the salt mines....

Ug. Yep, how many watts was the cube pulling?

Hm. Clocking down to 250 did not work, two sets of power supplies dropped off. Switching voltages didn't help either, below a specific clock speed (275) dies will fall off line.

Which makes *no* sense, but seems to fit a pattern: Titans have a sweet spot where they are stable in a voltage/frequency level. Run them there, things are good. Run them other places and the power supplies destabilize.

First day in the mid-80's (F) here, and wanted to let you know my Titan control cube here is running at 56c on the die, 90c+ on the power supplies. 300/325/325/325. I was running it full blast with two 750w Corsair M power supplies feeding the double plug to see if it would overheat the Molex. (oddly enough it did not).

NOTE: When it gets warmer the air cooled units will run a lot hotter. This is 20c hotter than it was a week ago with temps in the 30's. Be warned, I am clocking down to 250mhz.

On the Raspberry pi? If it's crap, just buy a new one on Amazon. Make SURE you get the 1.2 version Revision B and not the newer Raspbery Pi II or III.

This one should be it:

https://www.raspberrypi.org/products/model-b-plus/

Kano, you're being a bit of a jerk here: Luck is luck, and you know the numbers: Your pool has a .9% fee, therefore someone mining there will make .9% less than mining on P2pool. (edit: mining p2pool without a fee. p2pool ops can charge fees)

You are welcome to say that your pool has had a lucky streak, but please do not make the error of misleading people that just because your (or any other) pool has had a good run of luck that this means one whit of anything in terms of future performance.

Luck is luck, and the luck fairy picks blocks at random. People fall for selective bias all the time (remember the good streaks, forget the bad ones) but reality exists.

Neptune might not be worth the cost to fix at this point, but open it up, take off the heat sink, and look at the power supplies. Maybe one of them has exploded?

If not, what's a real basic way to do this? Bad cheap repairs. You could check each supply's output to see if it is shorted or 6-12 ohms. If shorted try ripping it off the board with a screwdriver if you don't have a very hot air gun. Actually you could just knock the two FETs off with a chisel or smal screwdriver and hammer, hitting from the side.

Oh yeah, that would be a way to do it on the cheap :-)

C

Try -.06 volts instead of -.03 volts. Then try 400mhz speeds. See what you get.

C

How good is your fire insurance policy?

Seriously, 125c is the breakdown point of the capacitors on the power supplies. 150c is the cut through temp for the FETs (the source of the heat). Temps on the board are read under the inductor (yes hot but not as hot as the FETs but it's kind of a heat sink).

When the caps break down or the FETs short and you have a big big power supply you will get to see fire shoot out of your miner until the supply crowbars. It's actually kind of cool to watch.

Also keep in mind that heat means waste, and you want less heat for more efficient hashing. So I would say cut the voltage down to -.06whatever and cut the frequencies down to levels where you get 60-70c on the supplies.

C

Ok, so how can I buy a Thinkpad with bitcoins? I like the X61, but it's old, so a 260 might be nicer.

Economics 101: It is impossible to make a profit in a perfect market. Mining Bitcoin is as close to a perfect market as you can get.

Consider it a lesson learned for your friend.

Update: Does not work. Pi keeps auto-restarting, probably one of the daemons is down. Will play with it tomorrow. Meantime amazon, ebay, everyone still has 1.2 Rpis.

C