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[email protected] electronicsmart@gmail.com is offline
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Default Testing a Dehumidifier circuit

I will try and create a circuit diagram by hand for this board, its a
small board so someone here can give me idea what failed thats stopping
from giving 5v across the timer IC.


James Sweet wrote:
wrote:
checked that the IC pin1 and pin8 should be getting 5v DC. its getting
about 0.3v so the timer is not kicking in which in result doesnt start
the relay through transistor. i have checked Diodes they conduct one
way, also checked all resistors and one 47uF 65v capacitor. There are
two small capacitors 0.1uF I believe which doesnt show me any signal.
maybe too small to be tested ? How do I check the transistor, Its C556B
PNP I believe. It looks to be ok because when I gave a small voltage
across two pins on the transistor the relay contacted.



What does the 5V come from? Something may be shorted across it holding
it down, or the power supply may have failed.