Hi, I've a class D car amp that was connected to battery charger and it worked fine with rem terminal attached to +12v to power on. Few days ago I notice that the amp powered on without rem terminal bridge to main +12v.
Any idea what that might be the cause? Amp works fine tho without rem connected to +12v.
Any idea what that might be the cause? Amp works fine tho without rem connected to +12v.
Did you read the manual? Without talking transistors at you I would take a guess that you have to connect rem to 0V to switch things off.
Just to clear things up. Amp should not be powered ON until REM connected to 12v dc. But my amp is powered ON with only GND and 12v.
Then, if that is what the manual says, it would seem to be faulty or rather not quite right. Your best bet would be to ask the manufacturer.
Otherwise...
These things normally operate on something called Open Collector Logic.
Your REM signal is external but the amplifier may have internal signals such as FAULT. Add another transistor and you can add another signal like TEMP. Those ae summed at the collectors of the transistors to a common /ENABLE, active low, signal within the amplifier. That's the idea anyway.
If you have a multimeter, then with the amplifier disconnected from its power, leave it some time to discharge, measure the resistance from REM to GND. You should see thousands of ohms. Then with the amplifier powered up and REM not connected anywhere measure the voltage betweem REM and GND. You should see close to zero volts.
Now the dangerous bit. If the resistance was high but you measured voltage at REM in the above tests try connecting REM to GND and see if the amplifier remains shutdown.
Of course the actual circuit used may not be as I have described it and also the manufacturer may have described it incorrectly as well. However if it is meant to act the way I am suggesting then since REM does not work as expected then if there are other internal fault signals then it is possible that they may not be functioning correctly. That would be a concern.
Again your best bet would be to ask the manufacturer.
Otherwise...
These things normally operate on something called Open Collector Logic.
Your REM signal is external but the amplifier may have internal signals such as FAULT. Add another transistor and you can add another signal like TEMP. Those ae summed at the collectors of the transistors to a common /ENABLE, active low, signal within the amplifier. That's the idea anyway.
If you have a multimeter, then with the amplifier disconnected from its power, leave it some time to discharge, measure the resistance from REM to GND. You should see thousands of ohms. Then with the amplifier powered up and REM not connected anywhere measure the voltage betweem REM and GND. You should see close to zero volts.
Now the dangerous bit. If the resistance was high but you measured voltage at REM in the above tests try connecting REM to GND and see if the amplifier remains shutdown.
Of course the actual circuit used may not be as I have described it and also the manufacturer may have described it incorrectly as well. However if it is meant to act the way I am suggesting then since REM does not work as expected then if there are other internal fault signals then it is possible that they may not be functioning correctly. That would be a concern.
Again your best bet would be to ask the manufacturer.
Will see what the manufacturer says about this however amp still working with only 12v and GND nothing connected to REM. I wounder the protection (LED) didn't kick in if it detected any fault across 12v. But I did witness audio just stopped tho.