wael_fathe

ok let me make sort of general steps for doing so 1- remove the cpu board or remove the 5vdc that comes from the standby power supply or the so called main sps 2- power up the device using on off switch this switch will switch on the main sps 3- short the coupler near by the sg3525 or pull its sd pin to what ever level guanrnatee the work for sg3525 5- test primary fet from gate to source looking for square wave in the range of kh (all fets removes and unsoldered ) 6- check igbt driver from gate to source look for square wave the range of kh (all igbt rectifiers have to be removed unsoldered )

Right. And to me, that's most conveniently done on the bench with the shorting technique. Unless perhaps you don't have a bench power supply.

OH MY LORD what an innovative design in old inverters the floating transistor that can not be driven because it is not refrenced to ground have to some how steal voltage from so where and put that voltage on capacitor that is hooked between its gate and source and violaaaa the undrivable transistor is driven but now each igbt emitter is hooked to seperate ground of a power supply .....in the past we create cap for drive floting fets and igbts now they create an entire smps for doing so .....they are telling the poor igbts hi you you not refrenced to cold ground , ok dont care we create specific ground for all of you

i do it because i wanted to check the validity of square wave before i do install the primary fets i also assume the same check can be done to rectifier igbts since they driven by the same sg2535? another question am confused at the main sps and soft start sps what is the dc input for those sps come from to me it seems logical that the main sps should work from all sources it have to work from battery because user may use only battery it have to work from ac because user may use ac it have to work from solar because in many models can use solar only as souce of power now after the main sps works it have to do it with out any command it is like the standby power suupply in the tvs monitors etc etc to continue after the mains sps works it produces the input for the soft start circuit which should be controllable sps the cpu desicdes if it should work or not i cant see those configurtion being always applied ? in some case i even see 3 sps ? while i am sure only 2 needed main sps and soft start ? the dc inputs for thos 2 sps are not like i imagined them to be (actually they should be like i imagine them ) ?

suppose i removed all primary fets and suppose that i also left the cpu borad connected the cpu will work when i power on the solar inverter and send the on pulse to the sg2535 how much time the cpu keeps on sending the omn command before it will eventually shut all down as it discovered that no output from the inverter and probably report one of the error states like 09 that is my real question thanks in advance mr colombos your contributions are already so genrous is there any sort of walk through or sort of guide on power on sequence and inner working and fucntions of diffrrent circuits on the inverter on this link that you provided https://forums.aeva.asn.au/viewtopic.php?p=88434#p88434 if not can i ask you about specific circuit within the schamatic in the link i do understand in general how inverters work but still modern tehcnology always asstonish us with its new innovations (soft start using power suppply + synchronious fet rectifiers + bidirctional charger inverter +the fact the sg2535 drives both primary fet and secondery igbt rectifeirs+) are few facts that i learned newly in this forum it seems more knowledge is needed , a walk throw post , that explain diffrenet circuits and that include power sequence will be of great help thanks

HOW genrous of you mr colombos i really appreciate your help regarding my qestion about drive signals i checked the lik you posted , the link shows the "forcing method" i need just the normal method with all fets removed sir where do i put my scope's black probe ? what ground do i have to use also how much time the dsp or the processor keeps the on command for the sg3225 on ? i AM AFRAID that if i test the pulses will happen very momentarily and then disappear . so where is the ground to i should use ? and how much pwm pulses willl stay that is my main question sir you generousity have effected me positively there for i provide gift for you and all this great forum memebers my book on chinese inverters i have repair cases with colors and pictures please give it to any biggnar who ask about the repair method of those simple inverter it also contain step by step approach to repair pure sine wave inverter with scope shots and describing the princeple of high side drivers and low side drivers https://www.mediafire.com/file/ba514ognj3ysep8/inverter++-++repair-cases.docx/file