Where would I find a description of the pinouts on the QMX board, i.e. the row of contacts on the upper right hand edge of the board? I want to measure the ADC 5V, PMW 5V etc. Trying to measure on the components looks tricky and easy to short something.
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Ludwig and others,
Ok, still no duty cycle at 10V with bad PS#1. DVM shows 5.3V at 9V in and 6V and 10V in.
Replaced with good PS#1 and see screen shot below. DVM reads 5.3V where as Diag screen shows fluxuating 4.8 - 5.4V. Now there is duty cycle of 20%
Noticed something that may be a clue, with the good board I can't shut the QMX down in the usual way. It tries to shutdown then reboots back up. I need to cut power to shut down. Hmmmm....
What think ye?
<QMX-12V-Good PS board.png>
On May 29, 2024, at 18:30, Tony Scaminaci via <
tonyscam@...> wrote:
Good point Ludwig. The PWM_5V signal is directly connected to the microprocessor. If Q106 is shorted on the original switcher board, the uP¡¯s pin could be damaged. This could explain why the swapped switcher board is behaving somewhat erratically.
On Wed, May 29, 2024 at 11:45 PM, Cliff wrote:
Another bit of info, I replaced the PS#1 board with one from another QMX. It worked ok, but the voltage varied quite a bit just sitting there, like .3 or .4 volts.
Cliff, I hope the overvoltage didn't damage something connected to the VCC rail and the now wrong load pulls the SMPS over the limit.
Could you show please a screen shot using the other SMPS? What are Duty max and Duty cycle (min, max)?
73, Ludwig
