for mine, nothing blew up unlike everyone else..(if it did, it would make my life easier), First one came broken and second one just died after 2use...I guess something must have became loose...(they are all 600w)dnmun wrote:how did your charger die? usually they fail when the ICL blows up.
did you take either of the 2 chargers you said had died apart to see what happened?
we have been able to fix most of them for a few cents each.
I have no idea what exactly the problem is but as far as i know nothing has blown(visibly) and when i plug in the charger to the AC it makes electronic buzzing noise.dnmun wrote:you asked at the beginning of your thread how to fix them. we have been able to help a lot of people fix their chargers but you have to open it up and measure the voltages as they go from the front end to the back end and include pictures so we can offer advice. we should be able to get them both working again.
The shipping cost is for batteries cargo in our website. 150USD almost 20KG batteries cargo.miuan wrote:I've had two of them fail.
The 240W unit appears to be dead on arrival, only the green light is lit, and no red light. It stays cool. Output is zero volts. It looks mint inside, no loose parts either.
The 900W made quite a lot of smoke last time I used it but it still worked. Haven't used it ever since, I need to have a look what's broken inside.
As for Evassemble: I'll never shop with you unless the calculator yields a much more sensible shipping cost for my location. 150 USD for a 3.5kg item is ridiculous. Also, is the speed specified for BPM motors at 36V or 48V? Come on Michael, your sig says you can do better, prove it!
okay I've done some tracing and gone through the circuit...now The output voltage of the charger shows 82.7v so how come it doesnt charge the battery? (also fan does not spin) I have not tested with battery due to it being fully charged at the moment but i'll see if it can charge the battery some point...dnmun wrote:ok buzzing. you will notice that the Switch Mode Power Supply SMPS has a front end and a back end, separated by the transformer. there is high voltage AC in the front end and it will sting if you let it touch you but if you can find where the output from the rectifier bridge is applied across the terminal of the capacitor on the front end, there should be a DC voltage with AC ripple on it.
that DC is switched at high frequency through the transformer by the power mosfet you will see in a heat sink on the side. when the current is switched through the transformer, it induces current in the output that goes to the back end. should be about 5 legs or maybe 6, some to the output and some supply current to the op amps and other parts.
the pulsing DC output of the transformer into the back end goes through a schottky diode into the output section which has the output cap on it and that cap smooths out the ripples in the output voltage from the switching. so just look and familiarize yourself with how it goes from front to back and see if you can measure the voltages on those traces. the wire shunt is where the delta voltage is generated to be used as feedback to the op amp that controls the amount of current that goes to the output. so you will find a trace from the high side of the shunt that goes over to the op amps. but if it is buzzing and you don't have any voltage in the back end then we will look more at the transformer leads. BOL, dm
So I found one loose 5W resistor near the big transformer. Soldered it in place and turned it on again. It works, but 2 things have changed.miuan wrote:The 900W made quite a lot of smoke last time I used it but it still worked. Haven't used it ever since, I need to have a look what's broken inside.
I recall I could hear the charger buzzing even before I had this problem, as soon as it started to taper down the current. But the 3rd led never lit before. So this is something to think about. For the record, I have the newer style charger with big heatsink, red LED display and Amp/Volt switch.dnmun wrote:the pwm frequency is so high you would never hear it i think. do you have a picture of which big resistor that was and what the value is? the fan would be turning on when the op amp that controls the output is telling the front end to send juice to the back. so maybe the current is not getting through to the back end like it should. these with the TL494 are different from the newer designs, but the 5W resistor may be a clue.
yes, the 166V is the rectified RMS voltage output from the bridge. it is DC voltage, charge stored on the capacitors that is then pushed through the transformer at high frequency, to induce current to flow in the secondary windings of the transformer, and that secondary winding is what is connected to the back end through those 5-6 legs soldered on the output of the transformer.pradeepswain wrote:The capacitors right next to rectifier rated 200v are showing 166v on multimeter. Is that the starting point in the circuit?
the 287V on the capacitors is the DC voltage sitting on the output of the rectifier diodes. i once had the data sheet for that TL494 and tried to understand how it works to cause the switching in the front end. and if those were some kinda "push pull" transistor pair that were a balanced pnp and npn transistors that would switch on and off with the sawtooth pwm output of the TL494. all just guesses on my part, but somehow the signal from the 494 has to get up to the base on those transistors, or gate if they are mosfets. that's kinda stream of consciousness, about the best i have right now.pradeepswain wrote:Thanks for the detailed information. Took a while to check the remaining circuit from following your comment.
I guess I've found the faulty part. The transformer YC-4803J does not show anything significant in output side. The input 4 legs show DC287v each. But voltage on the 6 legs on secondary side is 0.2v. I presume it should also have a fluctuating DC voltage. Or could it be the switching transistor that's feeding current.