SUA750RM2U - Site wiring fault

[palaniselvam_apc]

This was originally posted on APC forums on 5/29/2015

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I have two Smart 750VA UPS model no: SUA750RM2U. One of the UPS glowing RED LED it indicates site wiring fault. As per APC site wiring fault rectifying procedure i checked misssing ground, over loaded neutral wire and reverse polarity and i found ok. Also i checked another UPS connected with system it is working ok. I replaced the power cable and checked still red LED is glowing. So i contact APC customer care and informed this issue. They told that at present this model was stopped and spares are obsolete. I think problem occured in PCB and dont have circuit diagram. So if you have circuit diagram or give me some suggestion to repair the PCB.

[BillP · Accepted solution]

This reply was originally posted by Jonathan on APC forums on 5/29/2015

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Palani,

When you said that you have replaced the power cable, did you cut off the cable? Also, you have mentioned that there was a working UPS on your end - did you try plugging in the UPS in question on that outlet or vice versa?

Aside from those three reasons why would the site wiring LED would lit up, there are some cases wherein we have found that customer would cut off the ground prong on the UPS and for some they were using a 3-prong to a 2-prong adapter which could cause the LED to illuminate.

If in case you want this UPS to be repaired, you can contact our authorize repair center in the US - they are CoastTec.