[someloser]

I'm new here and I have a question about a circuit board. For our circuit board the light for the PWR BAD is constantly blinking. Does anyone know what exactly could this mean? I'm assuming that it means that there is no power, but could it possibly mean that it's low on power, or something else? Could anyone help clarify this for me? Thanks!

[Larken]

Whats the board for ?

[john-100]

the "power bad" LED indicates one or more of the supply voltages are not
within expected limits - probably one will be too low
you may find on your system the power good detector is on the uP control pcb and not part of the power supply

check the +5V supply is +5V plus or minus 5% ( 0.25V) (+4.75V to +5.25V)
and the +12V supply is 12V plus or minus 5% (0.6V) ( +11.4V to +12.6V)


with PC systems
the PC's ATX power supply sends a "power good" signal to the motherboard
via the grey wire going to the power connector pin8
without the power good signal the microprocessor is disabled and the computer will not bootup

at switch on , the outputs are monitored by a LM393 IC or its equivalent
the power good signal is held low until the voltages are correct

once they are correct the power good signal goes high (+5V) and enables the microprocessor

John