The COUT's connections are a mix of CAPs and Resistors, it seems. However, though the R+ labeled SMD seems to be a resistor, it has a polarity? Might be a cap/resistor combo. That, or the polarity indicator is just redundant. (This is on all my boards that function without issue. Except the one where the A1 chip is not mounted flush, and has thus, overheated.)
I suspect that the short across COUT46, by a screw from the fans, has just shorted the card, enough to keep it from initializing.
The board with the A1 that was not mounted flush, I assume had "shut down" due to the internal over-heating, once it had gotten to that point. In any event, the failure of that single chip, has led me to believe that the through-connections, the serial in/out on each chip, demands that the chips are chained. Failure of one, would, in some cases, stop the whole board from responding.
Removal of the chip, would seem to imply that a jumper be soldered, to bridge the through-connections, where they would normally be communicating "through the chip", to get to the other chips down the line. However, without the jumper, it seems like it should be possible to communicate with the chips up to that removed chip.
The work, I assume is coming in through the U8 chip, and returning back to the Ras-Pi, through the U5 serial linked chip. U8 is top-right, by the four other chips, I assume setting-up the distributed workload through U1, U2, U3, U4. The U5 chip is at the end of the serial connections from the chips, going directly back to the Ras-Pi, which is why I assume it is returning work/solutions/shares directly back, to be processed for diff-targets, to determine if they are solutions or just shares.
However, I could have that backwards too... U8 might be sending the work to the chips, and U5 may be the return of processed data. However, I am about 90% sure I have the previous paragraph correct this time. xD
The chips are sort-of isolated in groups of four, by two separate clock-timers or frequency controllers. Chips U60 and U61 are tied to four independent 1-wire connections, which are tied to a chip that has the clock-crystal.
All the circuits in the center, seem to be just the voltage regulation. Odd that they all seem to be built as individual regulation units. Might be why the new versions just made one whole power-regulator that was simply more robust, as opposed to 8 individual mini-regulators. There is power-isolation, as the chip on mine, which overheated, had a matching voltage-regulator which was also overheating.
I wanted to remove the caps and resistors from that board, which had the non-flush overheating A1 chip, and place them on the other board with the previously shorted connection... However, I had to craft a special soldering head to desolder the SMD components. That is taking longer than expected. lol. It was easier to do that, then to attempt to rework the non-flush A1, which I assume is actually burned-out and shorted inside anyways.
I am not sure how easy it would be to jumper/bridge the small connections for the data-lines... However, there are tiny inline (resistors or caps, can't read the numbers on them)... in the two center datalines, of the four. Not sure if that would impact the integrity of the data transfer. This is a question only AMT or BITMINE or TECHNOBIT can answer. Again, I don't have the schematics, and have not taken a strong look at the pinouts on the A1's in a while. I had no intentions to EVER get this deep into the design process.
The A2 board does have a few sets of caps and resistors, of a similar form-factor, just outside the heat-mounting area. There also seems to be a lot less micro-caps for filtering, directly around the chips. Roughly about half. However I do not see any crystal clock components... They may have settled for on-chip clock controls with self-oscillators. The controller chip also looks more like an ATMEGA-32 or ATMEGA-64, or a RISC processor. I would assume RISC, due to it being cheaper, and having more sister-components.
Ordered a new PSU for my computer, so I can rape the PSU from that, since it is way overpowered for my PC, but ideal to run the last two card with heat-sinks, that I have. Once I transfer the heat-sinks to the other cards that came without heatsinks. Should be here by tomorrow. Then, hopefully I will have almost 1GHs total. 580GHs + ~400GHs = ~980GHs (Not including errors, which, oddly are counted towards the GHs output, even though they were not valid, thus, not a hash. Makes determining the actual output a pain in the ass. Always says 580GHs, but when errors start, and get worse, the output is actually only about 480GHs in the pool. Just requires a reboot, and the errors go away for another day. xD The program needs a frequency tuning area. Though you SET a specific frequency, the output is not "calibrated", thus, it is ballpark. Sometimes you have to tell it a higher or lower frequency to operate, to be that actual frequency. That is how you tune cards. That is something that 7970's demand, in order to operate at ideal speeds. Not sure why that was just reduced to "Power-save", "Normal" and "Turbo"... Those should be user-settable. However, limited to the MFG MIN and MAX, for obvious reasons. xD, Guess I just gotta PuTTy to get it done.
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