Gaber Mohamed Boraey
Full Member level 4
hello
i have SMPS circuit, with uc3845B pwm ic, the start up resistor is 100k, the start up capacitor is 47uf, 25v,
this circuit is for charging 6 batteries " lead acid types ", 12v , the batteries are connected in series, so 72v is the total voltage approxoimately, and the charging voltage to be about 85v " aroudn this value "
this circuit should start once i plug the cable in electricity, and should read 300v at the smoothing capacitor which is 47uf, 450v, and that is already happens for now, before this capacitor had bad terminal and ive changed, i thought it will solve the problem, but i found that the problem is still,, whih is no output voltage at all for this circuit
this schematic is similar to the circuit i have , please look
I changed the start up capacitor with good one, checked the start up resistor and its ok, also I've checked every component at the primary stage and the secondary also, nothing bad, except the pwm ic of course as i can not test
so i ve changed with new one, " that maybe still the problem, in other words it may be bad ic as I've heard that some are bad even new , so I am not sure"
I also tried to bias the ic with outside power supply, after taking out the start up resistor, upto 15v and 1 A, but it not even turn on the power supply, " this is all and the mosfet in the circuit,
how you think of this problem?, it still the ic issue?, bad ic , because it not turn on even with outside biasing?, or anything I can do for be sure of the problem?
regards
i have SMPS circuit, with uc3845B pwm ic, the start up resistor is 100k, the start up capacitor is 47uf, 25v,
this circuit is for charging 6 batteries " lead acid types ", 12v , the batteries are connected in series, so 72v is the total voltage approxoimately, and the charging voltage to be about 85v " aroudn this value "
this circuit should start once i plug the cable in electricity, and should read 300v at the smoothing capacitor which is 47uf, 450v, and that is already happens for now, before this capacitor had bad terminal and ive changed, i thought it will solve the problem, but i found that the problem is still,, whih is no output voltage at all for this circuit
this schematic is similar to the circuit i have , please look
I changed the start up capacitor with good one, checked the start up resistor and its ok, also I've checked every component at the primary stage and the secondary also, nothing bad, except the pwm ic of course as i can not test
so i ve changed with new one, " that maybe still the problem, in other words it may be bad ic as I've heard that some are bad even new , so I am not sure"
I also tried to bias the ic with outside power supply, after taking out the start up resistor, upto 15v and 1 A, but it not even turn on the power supply, " this is all and the mosfet in the circuit,
how you think of this problem?, it still the ic issue?, bad ic , because it not turn on even with outside biasing?, or anything I can do for be sure of the problem?
regards