Sorry for the long winded post but there is a bit of history to this.
Items involved are a Sola 305 UPS (manual and specs here, an old HP 6306 (AP) Computer (in new case with larger power supply separate sound card ) and its HP M40 D5269A Monitor.
Initial fault (yesterday) was that the computer's BIOS (running XP Pro) stopped recognising the DVD and CD writers (Pioneer and Acer) on about 90% of boot ups. Unknown to me until later (when the UPS failed) my family tells me that this was preceded by what may have been a power surge (flickering of lights, lights went off then on again brighter for a moment) while I was out.
Twice while trying to determine the fault the UPS went through a phase where when it was turned on the relays continually cycled. As the UPS sits on top of the large computer case, and I had just had the PC case open, the first time I thought it was a wire inside the case hitting the fan. Turning the UPS off both times stopped this.
Shortly after the UPS died (no power to any of the 3 protected outlets). The monitor also appeared to die ( no pic) but reseating the PC's video card seemed to fix this. Opening the UPS I found a vaporised small section of mains track on the UPS PC Board at its thinness point (the plastic case was also blackened above this) which I have repaired by soldering a mains gauge copper wire across the small (2mm) gap in track. This repair seems to have fixed the UPS. However the UPS now cycles its relays if I connect the monitor to any of the protected outlets (it also seems to rapidly cycle the monitor's power supply). The monitor and UPS work fine if I use the monitor on an unprotected outlet on the UPS or from another separate wall outlet.
The BIOS is still not always finding the optical drives on all boot ups so I am tempted to just go out an buy a new UPS anyway while Dick Smith has them on special . I wonder though if I should also be concerned about the monitor and perhaps the power supply inside the PC. Any views on the cause and if I should be looking further than just replacing the UPS?