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Hello Ivica I'm sorry to hear of your problems and I'm sure between us we will be able to solve it in the end.? I don't think the occurrence of solder blobs on SMD components is particularly high though for sure it isn't zero; no manufacturing yield reaches 100.0% and neither does testing.? The number of boards with of PCM1804 problems is not known. The group here is not a very accurate indication because the probability of people posting with a problem is very much higher than the probability of people posting about a success. Nevertheless the number of specifically PCM1804 failures, is concerning. I have had discussions with several well-respected and highly experienced members of this group and even with our collective knowledge and experience it has not been possible to determine a probable cause. At the current time component source problems do not seem likely as the explanation. But other explanations also don't fit the available evidence.? What we did do here is modify the QMX+ PCB Rev 2 boards so that the SMPS circuits are on the main board, not on plug-in boards. This both reduces the possibility of constructor error and allows us to perform more detailed and deep testing of each board prior to shipment. It has not yet yielded any further data on likely cause of PCM1804 failures nor at what stage the failure occurs. I also made changes in the more recent firmware release to bring up the 5V rail more slowly and pessimistically (and similarly in reverse, at power down). It's not yet known statistically whether or not this made a difference, nor whether Rev 2 boards were less probe (or even immune) to failure; and the changes in the firmware release were certainly harmless but whether or not they were beneficial, is impossible to know, given that the cause hasn't been isolated. So they were a shot in the dark really. I wish I had more definitive information to provide but neither I nor others yet have it, despite a lot of investigation. 73 Hans G0UPL On Mon, Oct 7, 2024, 23:15 Ivica - YU1QRP via <yu1qrp=[email protected]> wrote:
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