HI there.   I have been very happy with the DROK 4310 PSU/UPS up to now.  Great value. However it stopped working last night after many years of use.  The unit was suddenly getting very hot and the voltege was dropping off quite fast.  Being what I assume is out of warranty and being an electronic engineer I decided to investigate further.  I allowed the unit to cool down over night and Initial diagnosis identified that the in put voltage was getting trough the connector/fuse and being applied to the circuit board.  A look at the output identified that there was now zero volts coming out.  On looking in side I noticed that there is a 1000uf 16Volt electrolytic capacitor close to the output stage and that this capacitor was bulging and most likely contributing the fault.   I have ordered a new capacitor to replace this item but wondered if you would be able to supply me with a circuit diagram so I can further investigate if the capacitor replacement is not the only problem.  I think you product is great and I would buy another one but I dont think you sell these item anymore do you?