Slight bump to this thread, given that I've now had two of the production units in hand to play with. Much of my original review stands, so I'm mostly going to go into some differences and updates with regard to v0.5 production version.
Astute observers have probably noticed I updated the picture in my StickMiners thread. Those who have been using the picture of the engineering sample with the faked-out green heat sink in their marketing material (asicpuppy/bitcoinware/holybitcoin/others), feel free to replace with clean PNG versions of the actual production unit below (thumbnails have forced black background, full images have proper alpha):
These ended up actually being a combination of both production units I have, and I'll go into the why later.First, a nice top view to show some of the changes with annotation:
The annotated bits are straight from sidehack, who did a pretty good job of pointing out what was new in v0.5 - and yes, one of the major changes is the pot direction which now, thankfully, increases voltage when turned clockwise.
From left to right: pads on back, reset cap out from under heat sink, aligning the TX resistors, pot direction change and pot PCB trace snafu.Other than those changes noted by sidehack, there isn't really any difference in terms of the hardware layout.
It appears a different board house or production line was used for the PCB. The new color is slightly different, it has a much more metallic sheen (more transparent solder mask), the silk screen uses a different process (there was also a silk screen package outline added for the LED, or that simply got lost in the other process), and the via drill is very slightly larger - which, thankfully, didn't cause any issues with things like traces getting mangled.
| | silkscreen detail | vias detail |
| |  |  |
The back side of the board does indeed have the silkscreen for the test pads which takes away some on-the-spot guesswork, and also adds the GekkoScience logo as silkscreen. The test pads are still exposed, so if you wanted to add a heat sink on the back*, make sure you're not shorting things out on them.
In terms of assembly, I was happy to see that there wasn't a spray of solder balls on the board, but hopefully things have improved down the line as far as the pick-and-place and need for manual rework goes. I ordered mine way early in sales ("first!") and my units were probably among the first to be produced as well, so with any luck this is already the case. The only reason I bother to mention this is because of things like this:
The capacitor on the right does not actually make contact with that pad, the one in the middle apparently does - but I'm not convinced that's due to an actual solder connection, or it just happens to rest on that pad making contact. This is alongside some general crustiness of flux and a few gnarly joints from apparent rework. This is why I ended up combining the best of both units for the StickMiners thread picture.
The heat sink is the new green color which does look quite nice even though I had gotten used to the nice golden one. They're still tapped all the way through, but that's okay. The screws used were changed as well, from pan to countersunk, shaving off about 0.5mm in overall height; more could be gained if the board had actually been drilled countersunk as well, though there's a via (and potential inner layer traces) that would probably nix that unless moved.
In terms of QA, that board with the iffy capacitor soldering does hash away just fine, but d1 shares found refuse to blink the blue+orange LED; the orange LED at least does work when testing it with a DMM, but I haven't yet poked at it further to find out where the issue with the lack of blinkenlights might be. On the up side, I did mention in my original review that the LEDs are rather bright, which still holds for the production units; with a nonfunctional blink part that's less of a concern and saves a fraction of energy
In terms of software, the production units now have a nice identifier which can be used by GekkoScience's version of cgminer (until pull request submitted and accepted, you will have to use that version), and is used by bfgminer as well; Luke-jr added support for the Compac and helped with the identifier bits. I had no problems getting the Compac working with either of those popular pieces of mining software, which means a host of third party software (e.g. GUIs) that uses them as a back-end should work with the Compac as well.
With things up and running, I also ran a few more tests with regard to *putting a heat sink on the back (see note above).
On the engineering sample I put a small heat sink that was pulled from a motherboard -
with the help of reddit, I was informed this was off a
Chaintech board.
You can still get these, though the
little ones for smaller chips are a lot more common, so I ran a test with one of those on one of the production units, and without one on the other.
While not terribly exciting, the temperature difference in stagnant air for an upright orientation at 5.5Gh/s@0.60V was 3.7°C, while moving air (small fan ~10cm from the miners) difference was about 1.4°C. The larger heat sink fares better but as that's on the engineering sample, can't fairly compare the two.
Similarly boring was checking the ideal orientation and fan position - in the good tradition of "I could've told you that much!"-research: laying flat on their back with the fan blowing parallel to the fins gave the lowest temperature increase from ambient, with upside down and the fan blowing face-on to the heat sink being the worst. I know, shocker.
Both the engineering sample and one of the production units have been running pretty much non-stop since September 21st at the
Compac solo mining club and
Nexious (if you have a minute, throw him some thoughts) respectively without a single hardware error.
So my original conclusion also stands and I hope to see more from GekkoScience in the future, which I undoubtedly will as long as they can get chips
