Quote from: the_electronrancher on February 04, 2018, 01:32:22 AM

Nice work!

I had a board like that with intermittent 0 and not 0 asic.

So if the chips have core vcc (which they do, your number is right) but they don't talk, what's next?

We're assuming they do (well, at least 62 did); my guess is the backplane is series/parallel with all three chips in parallel on the power and ground plane as opposed to three true serial strings tied together at both ends. Nice because the power plane is more stable and uniform, bitch because an open chip would be masked by its' neighbors (although you might see this in heat maps, as the chip would not be running at idle and its partners would be a bit warmer because they are carrying more current through them to the next series of three. Hm, where is my peek....)

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They need IO vcc, they need clock, and they need an unbroken connection to rx and tx on the header.

Hm. Is each chip wired to rx/tx on the header, or do they daisy chain between the chips? There's advantages to either way, but if they were all in parallel and one chip grounded it would sink the whole line (and rx/tx would read zero). If series any one chip could sink the string if it went open. Hm.

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And they need to be alive, but since they came up once it's likely they are, and are just suffering an intermittent issue with one of the other items.

Maybe. If one of the 63 put the tx/rx signal to ground or if it broke the chain that would show up as a dead board. The question is which one is doing it?

On titans as a comparison, the 4 main dies on each chip are connected to a common signal bus that can be isolated per chip by removing a 0 ohm jumper. However the hotel power and ground cannot, therefore if a die shorts hard the board is junk. If it shorts soft you can isolate the signal, and if it fails open you just have three dies running.

Back to the S9, there's also a second supply on this board, looks to be a 14.5 volt supply, I was wondering if that was series shared hotel power for the hashing chips.

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How good's your scope?

Pretty good, it's an older Tektronix T922. Main problem is it's only a 15mhz scope, I should upgrade it one of these days.