Good day. I have a MUST PV1800 3kw. (I beleive a Axpert clone The display lights up, but is blank. On AC it gives power but on battery it beeps and shuts down. Could it be the sof bus TX?

My understanding is that the Must Power PV1800 models are similar but not identical to Axperts.

The fault you describe could be many things, the lack of display takes away some of the best clues.

Perhaps try and get the display working first. Unfortunately, I've not seen any schematic traces for display boards, for any of the three main variations.

Edited November 22, 20223 yr by Coulomb

Hie, my Must pv1800 is lighting up lcd but not showing anything and all three leds (ac/inv, chg, fault) are flashing

On 2024/09/23 at 5:35 AM, KudaK said:

and all three leds (ac/inv, chg, fault) are flashing

That sounds like they inherited the poor capacitors in the power supply. Search the Repair Journey thread for which capacitors to replace, assuming that Must Power left the power supply largely the same as the Axperts. 

4 hours ago, Coulomb said:

Must Power left the power supply largely the same as the Axperts

I can confirm that the SPS circuits are pretty much the same in the Must units as the axpert family. Some of the capacity values are slighlty different but very close. You are looking topright hand side of the main board at the capacitors ranging from 10uF 160V - 1000uF 16V. I find it's worth changing them all out for good quality ones.