Posting purely for informative reasons, however it appears that Bitmain are still churning out crap.
I have just received a delivery of 12 x new S19 Pro (110T) from Bitmain, and within 2 hours of commissioning, I have 3 x dead hashboards (across 3 x miners) with 0 asics. They are clearly not giving a proper soak test. I realise of course they will exchange on warranty, but it's so much hassle as you have to return the complete unit (compared to Whatsminer for example, who will let you return a faulty hashboard on its own).
Speaking from very limited experience, the couple of S17 boards I've seen and repaired the solder quality was appalling. I expect the S19 are of similar quality.
With a few thermal cycles and transportation vibration I'm hardly surprised that they end up failing.
I think they must use OSP on their bare boards before reflow it leaves a nasty resedue if not reflowed properly, leading to weak solder joints.
All the fixes I've done were achieved through reflow/resoldering of the suspect ASIC's, on the S17 the hardest part was removing the heatsinks without damaging anything else. I think the S19 uses a different heatsink strategy, so might be easier to rework.
I don't think quality control for soldering is their expertise.
