Feel.free to drop some bitcoins in the research bowl or send repairs my way. However one may be able to mount a chip without reballing. My error was working with these older chips.

We learn by doing. And people have donated time coin and chips so it all works out...

Well, in the "lessons cost bitcoin" category I finally figured out why I have been failing in mounting this chip on the danger board.

This is one of the "early model" chips that are on a tiny carrier and do not have a logo. Got three of them for .12btc a few weeks ago. And one of them I tried to mount on the danger board. But each time I tried to clean it up and put it down, the chip would short the 1 volt supply line. Every time. Over and over. I thought I was a complete loser.

Then I tried to put another one down on a totally good board. Pre-heated, aligned the balls perfectly, applied the heat to the top, after 30 seconds looked in and saw a tiny solder ball on the chip carrier.

CRUD! Now I know what has been happening: Instead of bonding the chip to the carrier board with high temperature solder, they used normal solder. Which means the heat from my air gun would heat the chip and not the board under it and as a result the solder on the chip itself would short under it on the carrier.

CRUD AGAIN! That's why this other chip was shorting. And why this chip I was putting on didn't even mount to the board, just made a total mess of things. So I removed the solder on the board, swore for awhile, and put the chip away.

I'll sell all three of them for .04 btc, as either souvenirs or if you think you can get them going. It's just the cost of doing research, but I would *HIGHLY* recommend that you do not buy old style chips unless you have a full reflow oven and pace placement tool.

Lesson learned. One good chip left, two chips in need of reballing. So I should be able to put this last chip on the 5 chip board, making both 6 chip boards, then if I can get these other chips reflowed I'll try putting them on the danger board. :-)

C

Side note: That lentbt guy on Ebay is running out of chips. If you want to do this, I'd suggest checking in with him. I'm going to wait till my reballing stencils come in from China and work with that for awhile. :-)

C

In the meantime I've been bbqing a test board here trying to resolder chips that have already failed install. The results have been far less than spectacular.

The big problem is the chips will not align, and due to the board differences in height between the remaining solder balls it's impossible to place the chip. So the result is a chip that causes solder shorts, blowing the 1 volt line. I've gotten to the point where I can just sit there and measure the resistance of the board's 1 volt line. Anything lower than 1 ohm means boom.

Oh well, I think I have to wait for the um.. stencil. Once I have that I should be able to do some real work by removing all the solder from a board thing, then putting on a perfectly balled (hah) chip. I have 4 chips that have been screwed, so I should be able to get something out of this.

Eventually my stuff will come from China. Just. need. to. wait. :-)

C

The safe max seems to be five chips, with that you can run at 20gh, and still use the stock heat sink with the fan blowing straight down full speed. Going to six causes all sorts of weird things.

So lard em up with chips.

C

Been there, done that, got better. However I will say that death is not a bad option in that case.

C (wasn't wearing a helmet but hell, it was the 1970's....)

Yep, however none of my miners have switched over to the fallback so stratum is still up. Whoops it's back.

Mine mine mine! All mine!

Ok, we're up to six chips, but it wasn't easy and this is where it gets more real.

In a nutshell, once you go to six chips odd things will start to happen. First you will hash at 24gh. Whee. Second your custom fan assembly with heat pipes will start feeling the heat as board temps hit 70c. Remember they were in the 40's earlier, now they are in the 70's. It's a bit warmer up here.



Note the larger heat sinks on the power FET chips. They read in at 120 f right now, without them I think the FETs would be on fire. Likewise the fet driver chip is getting hot, and the ground plane of course is at 70c which is close to 160f. I put the Al heat sink on the bottom there for a reason; the plate on the bottom with heat sink compound was getting to 120f+.

In a nutshell, the issue is one of heat load: The more you put on the board the harder the board has to dissipate it. I thought about going to seven, but I think I am going to wait for the water cooling block before I try for that.

In addition I screwed up a chip; put too much flux on it and the flux bubbled out from under the chip while under heat. Very very bad, it pushed one of the balls into another on the outside and created a logic short so I had to pull the chip. It's ok, just needs the official reballing treatment. Another chip in "reserve".

When the water cooler comes I'll try putting chip 6 and 7 on the other jally; this one will not be able to go past 7 at this point due to the chip coming off the board so I'm kinda stuck. I'll leave it at six for now.

Update: Slight miscount, the other jally has only four chips, so I took it to five with FET heat sinks. Running fine. Next up will be to take it to six when I get the water cooler. At that point I am running low on chips here....

C

Sure, however that difficulty spike will take me out as a CPU miner. .7 cats mined so far, I might make it to one on my own.

C

So last night I had my first fail in awhile; I tried to put an old style chip on a completely burned up board. Found a pad that was mostly flat (repeated attempts by previous owner to add chips were spectacular fails) centered the chip, and hit the heat.

Shorted the 1v line. Odd. So I pulled the chip; the solder under it globbed together in one place. I had flux on it, I think the problem is that without the balls under the chip, the chip solder will tend to flow. Also the old style chips seem to have much smaller solder pads on them, the balls might have just run as a matter of course.

Not the end of the earth, just means I have 3 chips now to practice reballing on. I'm going to try one of them on this board again later; need to figure out how to get these chips to go on a board with no solder for the heck of it.

But no more experimenting with good chips. Have 4 more showing up today, I think this will be the last of the chips I will be installing for awhile.

C

Catcoin craps casino has a nice ring. And craps is one of those balanced games.

C

Side question: What is the theoretical *maximum* a Chili can go if fully cooled? See I have a water block on this unit and it's hashing 39/37. But I could dunk the radiator into a 50 gallon ran barrel outside and suspend the Chili over it to bring the water temps down to 32 degrees. Can the chips go faster, or is there a theoretical maximum (the fact that the BFL chips are clocking at 5gh each *now* is without a doubt creepy.)

THere was a book long ago called "Circus world" in which "fire was free but information was not". Information was exchanged for small stones called "movils". So if you told a story, people would give you movils to tell it, then if it was good more movils to be able to retell it. Lots and lots of micro-transactions, but sitting at another person's fire was free (not being information).

I could see exchanging services (repairs and such) for movils. Actual parts and such would have to be in a convertible currency, but info could be dispensed via a small light coin like catcoin.

Hm....

C

Ok. Given the water is almost frozen, it would be cool to run a chili with frozen chips.

But I should think about the summer that's coming up: One interesting thought here is to mount a heat exchanger to an old 5000 btu air conditioner, and water cool from that directly. I wonder how hard it would be to build a water to air conditioner exchanger or just put the AC condenser in a big fish tank and put the water radiators right there. Or just plumb the water straight into the tank. Wrap it wih insulation and your cooling problems would be solved.

Hm. Well, that's the summer when this is all going to be running in the shed on batteries and solar panels. Speaking of which I should order a new battery bank tomorrow so I can take the solar tax credit. Hm.

C

Sure, 9n1gFH2PSh26TeHTkc16zEhDytH7GxQ5pM

Now even in my sig. Maybe I should start accepting catcoins for jalapeno repairs.

Catpool: Allow .5 catcoin withdrawls. Those of us on CPU want to fill our wallets with catcoin. :-)

C

Actually I love my power company this much. I'm mining bitcoins on the main systems, my thing is boosting the chips. But I don't have any GPU miners, so you go with whatcha got.

Hm... Wonder if I should pick up an old FPGA miner from BFL and hack it to run scrypt.......

C

9n1gFH2PSh26TeHTkc16zEhDytH7GxQ5pM

Purring along, I should put that in my sig. Will work for catcoins. :-)

True, if you crack the case you will find that. However oddly enough I have a use for old jally supplies, one is powering a beautiful halogen lamp that had it's power supply die years ago (4 amps at 12 volts needs a big power supply). The other is for a peltier cooler based fridge that had it's power supply (12 volt 4 amp) die as well. So oddly enough how can you screw up these things if the jally supply decides to explode :-)

They would also make good 12 volt battery chargers oddly enough.

C

What I will probably do is put two of the new chips on one board, one on the other, and run 7 chips on one water cooled, six on the other with air cooling. Then hold the last chip in reserve to see if I want to go to 8.... :-)

C