tryed to repair 7 DC-DC-Platines from Solarinverters need help how i can find a short

[loler55]

hey i´m depressed since I have 3 weeks holiday because of Corona... and My Grandpa had recently a Heart attack.

normaly i repair solarinverters as hobby i just replace the boards since i have so many of them.

now ive tryed to repair 7 identical Boards From Fronius IG Solar Inverters just for fun and to keep me busy.

im a Electrical Master and i have buyed a Hot Air Soldering Stadion Last Week ,and i have looked so many try to repair videos from mymatevince and tronicfix on youtube...

both statet that you can search shorts when your meter peeps on both sides from a Capacitor against earth..

now when i use my meter on these boards it peeps overall on all sides from the Capacitors.

i found out that it is the same on a known working Board.

now i looked how many Ohms it is and i realise that it is no short when it peeps when i have sereveal Kohms resistance..

i wonder how other guys can find shorts when it peeps overall
or i need to look if the resistance near 0 Ohms?

i
on 2 of the boards i found a burning Capacitor not on the same position but i tryed to change these 2 and the resistors near them
but after that its dosnt work at all

on the other 5 i cant really see the problem no burnings or bad solder points

all of These Boards have LEDs to Show the Voltages is there, all of them working fine but the Inverter dosnt can make a Conection with one of it.
the board to board comunication dosnt work

i have one empty board with all parts unsolderd just to learn soldering with a hot air


need some tips here just to now one board repaired cost 150 euros


DC - DC Platine Fronius für IG 20-60 HV Wechselrichter 4.070.222

spend over 15 hours to it and now its feels that i can just smashed in a bin

 

[FAST6191]

Continuity testers are odd things and can send you down paths that a resistance check might not.

kOhms resistance might be a bleed resistor for the capacitor -- if they are outputting mains voltage with those capacitors (or smoothing a mains output) then you want something to get rid of the charge on the capacitors when not in use but at the same time not interfere with general operation.

Likewise is it shorts you are looking for? If I am dealing with popped capacitors I am usually more concerned with the esr (equivalent series resistance, usually measured at very high frequencies) which you want a more dedicated device for (I don't know that I have ever seen a meter do ESR, and even if I have it is very rare as even some of the high end fluke stuff won't have it), though ESR meters (or options for it on component checkers) have plummeted in price these last few years.

As for what to do next if you have a working board then time to measure voltages (careful if things are at mains) on the working board and compare them to the dead ones. Indeed after visual inspection, tugging on the wires and the like that is what I would do before I consider any capacitors (assuming capacitors going pop is not a problem).

 

[loler55]

Continuity testers are odd things and can send you down paths that a resistance check might not.

kOhms resistance might be a bleed resistor for the capacitor -- if they are outputting mains voltage with those capacitors (or smoothing a mains output) then you want something to get rid of the charge on the capacitors when not in use but at the same time not interfere with general operation.

Likewise is it shorts you are looking for? If I am dealing with popped capacitors I am usually more concerned with the esr (equivalent series resistance, usually measured at very high frequencies) which you want a more dedicated device for (I don't know that I have ever seen a meter do ESR, and even if I have it is very rare as even some of the high end fluke stuff won't have it), though ESR meters (or options for it on component checkers) have plummeted in price these last few years.

As for what to do next if you have a working board then time to measure voltages (careful if things are at mains) on the working board and compare them to the dead ones. Indeed after visual inspection, tugging on the wires and the like that is what I would do before I consider any capacitors (assuming capacitors going pop is not a problem).

the problem is that it worked only with dc voltage and ac voltage i mean 230v AC and 300V DC are on this board
a little bit dangerous to measure voltages
this board is under the ac dc board and should be a problem to connect all things and measure then
i dont think thats a good idea
its like measure voltages in the running microwave
without DC or AC the inverter wont start
last time i get a electrical shock from one hand to the other over 800V DC and i can tell you you donst now that you can louder Screaming like a Woman


i trough one of the 7 boards must have a shorted Cap or chip

 

[FAST6191]

Yeah high/mains voltage electricity is a fun one, especially if you do decide to stick it across your heart. If it is DC in then it should be effectively isolated. Clip one end of the multimeter to a ground plane and put your other hand in your pocket, use the remaining hand to probe around. If you want to wear a glove then do that too (and if you wear any rings you don't want to take off then definitely glove up).

If you want you can figure out how to disable high voltage output so as to only measure the logic side of things, though if ti has feedback to determine measurements of outputs that can get hard to do well.

Measuring if it is all in a case can be hard as well. If you have sacrificed one then maybe consider cutting a hole in the case, of it is is just wires connecting between boards then make longer ones so you can measure things/test things.

Generally though you are not going to be able to get too far if you don't measure voltages, possibly even with an oscilloscope.

 

[loler55]

Yeah high/mains voltage electricity is a fun one, especially if you do decide to stick it across your heart. If it is DC in then it should be effectively isolated. Clip one end of the multimeter to a ground plane and put your other hand in your pocket, use the remaining hand to probe around. If you want to wear a glove then do that too (and if you wear any rings you don't want to take off then definitely glove up).

If you want you can figure out how to disable high voltage output so as to only measure the logic side of things, though if ti has feedback to determine measurements of outputs that can get hard to do well.

Measuring if it is all in a case can be hard as well. If you have sacrificed one then maybe consider cutting a hole in the case, of it is is just wires connecting between boards then make longer ones so you can measure things/test things.

Generally though you are not going to be able to get too far if you don't measure voltages, possibly even with an oscilloscope.

thank you for the massive input now i try to build a setup with old parts and figure out how to disable high voltage then i can go and measure save nice idea i see some jumper and i try what tey do

 

[FAST6191]

thank you for the massive input now i try to build a setup with old parts and figure out how to disable high voltage then i can go and measure save nice idea i see some jumper and i try what tey do

I forgot to say yesterday but you can also solder wires onto various points on the board, run them to outside the case and measure those. Makes things a bit harder, in the extreme case there can be some interesting effects upon components -- a long wire is a long antenna after all, and you might want to narrow it down to things you think you want to measure rather than just being able to probe whatever component you like at will.

 

[Dejablue]

Have you made any headway i have same problem with fronius dc board ?