MobiFlight Community Support

I have a Mega running the annunciators for the fuel and electrical panels on my PMDG 737 (some 25 annunciators in total). Occasionally during a lights test, the Mega will lose USB. Mobiflight is still running, and successfully communicating with 3 other Megas connected.

Re-starting Mobiflight brings the troublesome Mega back to life - ie, re-establishing the 'lost' USB.

I think it might be power related, because the dropout usually occurs during times when all annunciators are lit (eg, a lights test).

Both the Mega and the USB hub it is plugged into are powered by a 12V 5A power supply, drawing no more that 1.2 A, even during the lights test. This same power supply also powers another Mega that currently only runs 6 annunciators. It remains connected when the troublesome Mega drops off.

I guess another possibility might be a grounding issue. I'm yet to connect the grounds of the two Megas, though they share the same power supply.

Any advice on other things to consider?

Many thanks,

Paul

It’s not only about how much you support to the Arduino. The chip on the Arduino just is not strong enough to drive all the current for the LEDs through the outputs. You have to either use a driver chip, lower power leds or reduce the number of LEDs that light up simultaneously.

Thanks Sebastian. My mistake. I accidentally had a stepper plugged into the Mega - from testing. Now powered separately the Mega is fine. Don't tell Pizman - he'll tell me off. :-))

Paul

We needn't tell him, he'll read it here

Haha!

I will see if I can hide this thread from pizman.

MOD permissions

I can see unpluplished and hide topics, too .

Whatever..... Important is you find the issue and your system work fine again! Have Fun !

Unrelated question: I have a number of 5V 28BYJ-48 / ULN2003 stepper gauges in my overhead. They share the same 5V 3A power supply (not yet drawing the full limit). The gauges work very well, but the stepper motors get really hot, almost too hot to touch.

Any ideas?

Paul

Hi Paul,

don't worry, it is normal, that the stepper gets hot. That's because the holdingtorque. The temperature raises after the first use of the stepper because then the holdingtorque is active. Because of the holdingtorque you can not move the stepper manually.
Check the current of the stepper. If the current is above 250 - 300 mA in rest condition that may indicate a problem with the processing of the steppers.