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Yes exactly, idk why , maybe protection circuit is broken but that battery exxceds 4.2 easily . I need a solution to prevent that from happening.(by not letting it to charge to 4.2 for example )
Hi i need to reduce voltage of a 4.2v protected battery which is in a circuit. I need the output to be 4.1 or below it .. Also it's not important to do it by not fully charging battery. Any simple solution?
That was a wise answer :thumbup:
I wish you said it earlier, you're right I didn't connect the LEDs to correct path, cause lcd's flat cable is not easily accessible, I managed to connect negative leads to GND but they weren't supposed to be grounded!!
Then yesterday I connect(LED's neg) to...
Thanks for detailed answer! I got all the answers for my question)!
I took the resistors out and R2 was 1k and R1 is 10ohm, the inductor and schottky looks fine too, I also tried resistors with higher value (up to 100x)and they didn't change a thing. so this concludes that the FB input is not...
Thanks, so what explains the high current in this circuit in your opinion ? what if I add resistor at input? (if I add resistor in series with LEDs They are cool but IC gets hot)
I found out that(D256A) IC is lm2703 (a DC step-up) and It controls voltage of leds automatically (?).
I measured the current through leds and it's almost 0.9Amps! my new leds turned blue:/
Also now I'm sure that screen backlight is not EL and is produced by 3LEDs
--as schematics shows there's...
update :
I measured the inductor without LEDs and I read different numbers each time (variable from 40 to120volt!) that is connected to a schottky diode (output is 24 v at this diode,with LEDs it's reduced to 8.9v but causing extremely hot LEDs )
the input voltage of inductor is 3.5v(fixed)
take...
Thanks and yes, it sounds about right. It's possible that these electroluminescent lights were used .i have to inspect that...
Putting this aside, can I simply remove that "D256A "invert transistor from the board to evade the heating problem and use 1 led solution?
- - - Updated - - -
or...
update : with 3 new leds and going back to original setup, the ic is cooler than before(still gets warm but acceptable )
now the leds are super hot, any second they might die as well...
I can't edit my posts sorry, the 24volt connection is not connected to anything ,ive attached 1 led to somewhere with suitable voltage (2volt) on board
I used only one LED instead of 3 LEDS(I connected this led to a lower voltage pin on the board, the thing is these lcd backlight leds only need about 2.5 - 3 volt to light up, which equals 9volts at most but board is providing 24volts
and also about the inverter transistor ,can I test your...
Hi guys, this mp3 players lcd went black (dead led backlight) and I measured the voltage at connector and it was rated 24volts for 3 leds!,
I replaced 1 led and used another pin for it, it worked but the D256A ic gets really hot and shuts the device down after a couple of seconds. (even without...
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