Thank you so mutch. I will take somme pictures of my ups, the brand is ONPOWER, model- GUARDIAN 35 its realy good made. last year with help of the people from, i do not remember exatly the name of the forum i built one 24dc to 230ac 5000w power inverter using power jack boards and 2 transformers from old APC 3000 ups. Was a great experience for me, works perfect. When i mensioned the guardian 35, it has 2 big toroidal transformesrs, both 2500va, one 57v primary 230v secondary, the onther one is 27v primay and 230v secondary, this kind ups use a thicker wires and they are built to last and, i was a very negligent when i tyed to remove the beeping and shortcircuited the board. Is very hard to me acept the idea of use only the toroidal transformer, with chinese boards. Anyway in case, of using that board you told me, what you opnion based on the expecifications of the toroidals i told above?, Thank you very mutch for your post. NJM