Coulomb

Control board schematic here, for a related but not identical control board. Note that if the DSP chip itself is damaged, then the board is basically a write-off, due to the issue of finding a bootloader segment that suits the main firmware. You may be able to buy suitable replacement control boards, either from your inverter supplier or Ebay/Ali Express etc, but note that there are many variants with subtle differences, and vendors will often be clueless about these differences. You need a control board with a firmware that matches your model, otherwise you'll likely have an incompatible bootloader segment and will have difficulty reflashing a suitable main firmware. The EEPROM on the control board carries calibrating values for various measurements, so if possible transplant the EEPROM from the old board to any new one. It seems to be possible to use default calibration values, which actually surprises me. Good luck.

Fault code 90 means that the firmware thinks that it is running illegally on a clone. At least, that's what it means for Axperts (off grid models; Infinis are called on-grid models by Voltronic). If it's the same as with Axperts, you need either patched firmware (most unlikely for Infinis), or you have to get an updated firmware or serial number updating tool from your inverter supplier.

What do QFS and QFAULT return?

I see no photos. Why was the control board replaced? What were the firmware versions before and after the change? My guess is that you have a different main (U1) firmware that is incompatible with commands that the display (U2) firmware is sending. Or the U1 firmware on the new board is incompatible with your inverter hardware. I have no 17.xx firmwares at all. Does the inverter work in other respects, other than the display?

Yes. The MAX firmwares are designed for either the '2809 (older) or '28066 chips; the 75.xx firmwares (those designed for MAX models, not the ones for rack mounted Kings) are for the '28066 chips. You have the '28069 chip, which is the same as the '28066 chip except it has a bit more RAM and two extra accelerator modules (not needed or used in the inverter firmware). My guess is that there are occasional shortages of the '28066 chip, so they use the '28069 instead. Or maybe Texas Instruments' fabrication is maturing to the point where the '28069 has the same yield as the '28066, and the '28069 is completely backwards compatible, so they just concentrate on producing the highest spec version, simplifying inventory. I've heard of other '28069 chips in Voltronic inverters. That said, nothing in this crazy world is completely certain, but this one is very close to completely certain.

Display firmware version 03.25 looks much like the 02.xx series, at least at a first pass. Edit: On pass 1.1, I see that the display segments are all different. So this just has a different display, still only with one "head" (colour displays have 3 heads).

It looks like it might be a VM III (from the "V3 at the end of the model name), so you could try display (U2) firmware version 02.90, (ignore the DSP file), since you have little to lose, and I don't think you'll find 03.xx display firmware. As a point of interest, what was the display firmware version that didn't work?

You seem to have plenty of PV voltage. So try version 378.11; at worst it should get stuck at 200 V. But I suspect it will kick in at lower PV current than the present ≈2.5A. and ≈1.4A.

Yes, as far as I know. That presumably means that you have paralleling cards installed, and all the wiring is correct. I also assume that you must have the output mode of both set to PAR (parallel single phase mode). All I can suggest is that you check the output wiring (no neutral and live swapped, for example). Though I would expect fault codes if the inverter somehow detected that. You should have breakers on both AC outputs. Do you get AC out if you isolate one of the inverters? Are both inverters using the same battery?

It's version 75.85. It should work with your inverter.

Sadly, I have only one 75.xx firmware in my collection, 75.85. So IF it's a firmware issue, this might fix it. The hex file is dated June 2025, so if your inverters' manufacturing dates are later than this, don't bother with updating to this firmware. There is no way to go back to your 75.03, except by asking your inverter supplier for an update file.

I have no 03.xx display firmware at all. Is this for a clone? Is 03 perhaps a typographical error?

74.04 is the latest 74.xx firmware that I have. It does not support the QDOP command, so it won't allow setting 29 and two others to use SoC%. Sorry. I don't own one of these inverters, but I've read that you can only change these settings on the front display, not via monitoring software. Once set, you can do everything else via the monitoring software. I have not looked into this. Edit: BTW, from the looks of the label, I'd guess that this is a clone.

Glad you got it working, @bruno1975 I've not heard of needing to "restart" the inverter.

Thanks. I must have missed it.