9 Nov
2005
9 Nov
'05
3:41 p.m.
I think what I might do next is get a spare
comparactor chip of the same
type (LM339) and connect the power and ground pins to the power and
ground pins of the chip on the board (I am not _sure_ they both have the
same power and ground connections, check this!). Then link the inputs --
right way round -- to each of the 4 comparators in the undervoltage
circuit in turn. Put a suitable pull-up resistor (to the comparator power
connection on the output).
I have found the voltage under threshold isolating one by one the output of
the four comparator (desoldering the pin) and there is two voltage out of
range : +12V is 11V and -12V is 10V. In fact the two comparator of the two
voltage, if connected, shut down the power supply.
I have test the power supply without the two comparator output connected,
and it work , with load ... but I have tested it for a short time, no more
than 20-30 sec, I'm afraid of dangerous effect :)
Tomorrow I try to undestand how these voltages are low.
Alberto.
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Alberto Rubinelli Mail : alberto at a2sistemi.it
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ICQ : 49872318 Skype : albertorubinelli
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