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Bit coin miner From Ebay scrap (IV)

18 Jun

Overall the results from using the Ebay scrap were positive

The boards are a little long making programming via JTAG difficult, not to mention the 14 Pin IDC connector is not really suitable for a standard 14 pin IDC plug (a fact I discovered AFTER I returned from China with a bag full of parts).

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As we can see it is a little cramped by the JTAG connector (directly inline with a fan), yep I can say officially that even a 12 Volt fan is capable of doing serious damage to finger tips and finger nails.

Caveats

There were a number of issues with the FORA(For-a) video processing boards.

  • After digging about we find that the FPGA core voltage has been fixed at 0.97v
    This is a little low for proper mining
  • We had to strip out an additional component that supported the PCI bus as the part was running from the 3V3 supply.
    Failure to remove it would be driving the chip at 170% of its rating thereby forcing it to dump several hundred mA as heat…
  • Yep We had an Idea that there was something shitty about the power-supply setup…
    The Bellinix modules used are ‘programmable’ via an external sense resistor, problem was that when we replaced the sense resistor NOTHING happened to the supply voltage, in fact completely removing the sense resistor also had no effect.
    * UPDATE 29Th June 2013, we finally tracked this down to a defective Bellinix module…
    We can now adjust the core voltage for the FPGA via a system that reprograms the DC/DC PSU module.

     

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