TonyDI Posted July 24 Share Posted July 24 Hi everyone, sorry in advance for the imperfect language. I'm new to this forum, my name is Tony and I write from Italy. For several days I have been looking for information on a problem and it is nice to see that there are those who make their technical skills available to everyone. I hope I can do the same in the future. I am not an expert in Photovoltaic Inverters and anything else in the sector, I am an electronic technician and as such friends with various problems turn to me. I need help and your knowledge. A friend brought me an Inverter (UFLEX 22848P perhaps like the Voltronic with PWM 5Kva) which does not detect the presence of PVs. From a visual and measurement search I saw that some SMD components were burned on the PWM board (mod: 16-500244-04G). While for some components I was able to read the value and find them (D18,D19,D20,Q23) for one of them the value cannot be read due to burning (R76). In other discussions I saw that there are photos of the PWM in question but unfortunately the value cannot be seen there either. Can you tell me where to find the pattern? Or does someone already know the value or has one disassembled so they can take a clear photo? I attach the photos hoping they are clear... Thanks, have a nice day everyone... Quote Link to comment Share on other sites More sharing options...
jct Posted July 25 Share Posted July 25 (edited) Just a suggestion if you can't find a service manual on Google: Draw a schematic diagram of the section where you replaced faulty components, including R76, as well as to what bus/line R76 connects to. Maybe the circuit will make sense to you or one of us and the value can be calculated or at least estimated. Edited July 25 by jct Quote Link to comment Share on other sites More sharing options...
TonyDI Posted July 25 Author Share Posted July 25 (edited) Hi jct, thanks for the reply and suggestion. It's a good idea, I'll try to draw it in the next few days. Edited July 25 by TonyDI Setting wrong Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 26 Share Posted July 26 On 2024/07/25 at 2:20 AM, TonyDI said: some SMD components were burned on the PWM board Unfortunately, I'm not aware of any traced schematics for the PWM boards. The MPPT solar charge controllers are far more common, and we only recently came across a traced schematic for those. That corner of the board is near the MOSFETs. It's possible that this part of the schematic is part of the gate driver circuit. If so, that part of the schematic should be repeated for all 6 or so MOSFETs. You should be able to find a pattern, and find undamaged areas where you can read the value. I note that a common way for gate driver components to burn is for the MOSFETs to fail shorted, putting drain voltage on the gate driver parts. A good sanity check for MOSFETs and IGBTs is to measure the back diode voltage drip (source to drain or emitter to collector). About 0.4 V indicates a likely good part; a resistance reading of say 13Ω or zero ohms or infinite ohms indicates a bad part. Quote Link to comment Share on other sites More sharing options...
TonyDI Posted July 28 Author Share Posted July 28 Hi Coulomb, as suggested by Jct, I drew the part of the circuit of the burnt components. From what I understand it is not part of the Mosfets driver circuit. Will it be detection? there are no similar parts to compare. Mosfets and Transistors seem to be good. The drawing should be ok... Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 30 Share Posted July 30 On 2024/07/29 at 4:27 AM, TonyDI said: From what I understand it is not part of the Mosfets driver circuit. Will it be detection? Yes, I'd say so. That looks a lot like the detection part in the MPPT traced schematic: Your R76 looks like it should be 100kΩ, though if there are two in parallel, use 200kΩ each. It doesn't seem like the values will be critical. You probably want to start with 100kΩ and work down to no lower than 10kΩ, since this may affect current consumption when the solar charger is off. When the PV voltage is more than some 5 V higher than the battery voltage, then Q20 above or Q23 in your case will turn on, allowing the solar charger's power supply to bootstrap itself and draw power from the battery, starting the solar charger. Quote Link to comment Share on other sites More sharing options...
jct Posted July 30 Share Posted July 30 I agree 100% with @Coulomb. Quote Link to comment Share on other sites More sharing options...
TonyDI Posted July 30 Author Share Posted July 30 True, it's exactly the same. The difference is only the R72 which is not in the MPPT circuit, and parallel is not a problem. I will do as you say Coulomb, replace the components and do some testing starting with a 100k R76. I'll let you know as soon as possible. Thank you.. Quote Link to comment Share on other sites More sharing options...
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