On Jan 1, 2025, at 7:48?AM, Hans Summers via groups.io <hans.summers@...> wrote:

Hi Zrinko Ivan

My assumption is that the Chinese manufacturer does not install original chips, but copies that in many cases do not work well.

It isn't how it works. While the PCBs are manufactured and SMD assembly is in China, we don't use a Chinese manufacturer in the way that people submit a PCB and BOM to JCLPCB or someone (not saying there's anything wrong with JCLPCB per se).?

I have a trusted colleague in Shenzhen, a sub-contractor who I have worked closely with since 2014. Many of the parts are ordered direct from the manufacturers e.g. NXP Semiconductor, or Analog devices or from US distributors such as Digikey, Mouser and Arrow. Other parts like resistors and capacitors are sourced locally in Shenzhen from reliable sources but all the parts are tested by me and then the same suppliers used in all manufacturing batches. Everything is traceable and documented.?

Over the years there have occasionally been problems, things were particularly difficult during the global semiconductor shortage post Cv19. We've been able for the most part to quickly identify and resolve any issues that arise.?

The PCM1804 problem is a rather unique one that so far remains a mystery. Progress is being made. On QDX and on current Rev 2 QMX+ PCBs, we're able to test the board INCLUDiNG PCM1804 before shipment and I think we have a very high success rate at detecting failed chips. There was about a 15% failure rate in the batch, which were rejected here and not shipped to kit constructors. I don't think it's an ESD problem caused by the kit constructors.

So I think I'm making progress on the problem and hope to solve it finally got the QMX which is the remaining issue.?

73 Hans G0UPL