Hello all,
I bought a switch that suddenly stopped working.
Staying on the off button for 20 seconds and turning it back on did not work. Also other combinations with off button and hold down quiet button.
switch is charging via the charger. So there is no problem.
on the M92T36 I have no short circuits on the capacitors. The voltage is also present here.
if I hold the off button for about 12 seconds, it should go off completely. When I then measure the voltage at the battery, I have 3.60 V. When I turn on the switch now the voltage goes down to 3.50 V. So you can conclude that the switch reacts to the signal. But I hear and see nothing.
via the docking station I also get no image. The docking station only lights up green briefly and then goes out again.
What else could I look for? How do I find out if the video chip is defective?
You need an amp meter and measure what amps are being drawn. With the switch turned off (hold power button down for 15 seconds),:plug in amp meter/charger, you should get a drae of approx 0.2 - 0.4 amps, then if the switch is booting the amps go to zero for a second, and then it should then fast charge at 1 amp ish. If this sequence occurs then perhaps you have a display issue. Try turning the sound up full by clicking the volume button, then tapping the screen to see if it’s on, but not displaying.
I measured the current and there is only 0.4 A. It never goes up to 1 A, so this is an indication that the switch doesn’t start.
It doesn’t matter if the switch is charging or not.
It is often fixable but, it can be all sort of things. I would say first things to test are any shorts to ground around any of the chips. If that is all fine i would check resistance to ground on all the main voltage rails.
do you get any signs of life from the lcd? Does the backlight come on, do you see a battery charging symbol? Just FYI 3.6 volts is low for the battery and that voltage level will not allow the switch to boot. AFAIK you need somewhere around 3.75 - 3.8 v on the battery to get into HOS.
If you’re seeing 15v .47a on the meter when you plug it in, then m92 is most likely ok. You could start things off by pulling off the battery, plug the board into a charger, and then measure voltage rails around all of the MAX PMICS and fuel gauge. As already mentioned there are too many things that can prevent a switch from booting that are impossible to diagnose without you testing and providing measurements for us to look at first.