stuck in rectifying the problem in Emergency StandBy light charging circuit

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Thread Starter


Joined Jul 8, 2011
Dear All.

i have attached the circuit diagram of a simple 6V standby light used as home appliances.... what happened was i have changed the battery polarity once. after that suddenly some component burned out and not working now. am stuck in trouble shooting the problem.please help me and what could be the problem for this ? what component would have burned out..??? i have changed the "fuse" (2.2 kΩ Resistor which is in series with battery) .

thanks in advance,...

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Joined Jul 9, 2011
Well it looks like, if I'm inverting the battery voltage I will have a current path through the diode on the left upper side of the 6.8nF capacitor back through the bridge rectifier on the input then through your 2k2 resistor back to the battery. So these are the first components I'd check.
However, there are not many components in this circuits so one should relatively easy be able to find out which one has burnt.

Don't measure in circuit, as it can give confusing results.

first checks:
caps - shouldn't have a short circuit
resistors - shouldn't be open or have a higher value than they are supposed to
diodes - shouldn't have a short circuit / multimeter diode tester
npn transistor - shouldn't have a short circuit / multimeter diode tester
the transformer does only have two windings, they should'nt be open, (interwinding short circuits you can't measure this way, of course)


Joined Apr 5, 2008

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