Help needed to identify thermistor value in failed Avaya PSU

[alanb]

I'm repairing the failed PSU in an Avaya IP office 500. The inrush limiting thermistor appears to have failed, the markings are S.10 K275. Can any one tell me what the resistance value when cold should be or alternatively the equivalent part number on Farnell or RS websites?
Thanks in advance
Alan

[perieanuo]

I'll have to check but view the code you're sure it's the PTC inrush?For me that code is the parallel varistor 275V that protect from over voltage


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[alanb]

The code is correct but it is possible that I've wrongly traced how it is connected. I don't have the psu with me so I won't be able to check until tomorrow.

[perieanuo]

http://www.produktinfo.conrad.com/datenblaetter/500000-524999/500592-da-01-en-Scheiben_Varistor_S10K275.pdf
Remove it and check the fuse and bridge and chopper transistor then power on.you had an voltage spike or some 380V on your ps


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[alanb]

Thank you Perieanuo, you are correct. It is the a Varistor for over voltage protection.
Unfortunately this is not the cause of the fault so I need to continue fault finding on this psu.