Re: QMX won't power off and odd voltages on Q103
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Hi Kees
Remember also that we do test the USB connection of all boards here before shipping. The recommendation to add a bit more solder is more about long life. Since it doesn't intuitively look that secure even if there definitely is an electrical connection.? 73 Hans G0UPL
On Thu, Aug 31, 2023 at 07:53 PM, PHILIP GRAITCER wrote:
D103 ? 2.426 when unit on instead of -3.3V ?as you suggested.
Grounding the 78M33 (middle pin) turns the unit off
Phil,
The output of D103 should be "approximately" 3.3V (that's not a minus sign) and 2.426V is way on the low side. Grounding the LIN_REG_EN pin and turning the 78M33 OFF is good. Does it stay OFF when you remove the grounding ? That would indicate control had been handed to the processor and it enabled the 3.3V SMPS.
Speaking of firmware and loading new firmware have you reloaded the latest code AND checked the USB-C connector for good solid connections.?Hans recently released video (52 things....) shows relatively good soldering on the 16 USB-C connector pins but there are apparently a number of boards out there which are not nearly as well soldered and have "iffy" connections. I have posted details in other threads. The reason I call it an "iffy" connection is because the GCT USB4085 connector has 62mil length pins and the board is about 62mils thick. The pins also measure 0.15mm x 0.22mm and the plated via hole is 0.40mm+/-. That's not like "a BB in a rain barrel" but it does indicate good solder wicking between the pin and the via barrel is required. Since soldering those 16 pins is very difficult for the manufacturing facility it generally picks up a little solder from the via barrel plating ......but many times there is too much space between the via barrel and the pin. The result is poor or no electrical contact. Fortunately the 16pin USB-C connector is "reversible" and there are 2 pins for each signal which Hans wired together on the artwork ....so the chances of making a "good connection" are better but not 100%. Sure hope I didn't confuse anyone more.... just trying to help.
73 Kees K5BCQ
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