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Replacing unknown NTC Thermistor in Corsair CX400
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Re: Replacing unknown NTC Thermistor in Corsair CX400
Originally posted by goodpsusearch View PostActually it is more like:
10A for 1.5mm2
16A for 2.5mm2
20A for 4mm2
25A for 6mm2
32A for 10mm2
Where did you get those values?? For what country??
That (almost) looks like it is for Aluminium...
What I've found (for Germany) is something like that:
https://www.zaehlerschrank24.de/info...tstabelle.html
But that's just the most simple one, normally you have a table, depending on the laying method and the differences can be rather high...
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Re: Replacing unknown NTC Thermistor in Corsair CX400
For 1.5mm2 cable its maximum current depends on many factors, but let's say it is ~ 15-19A.*
So, a 1.5mm2 line gets a circuit breaker with value of 10A, because as we know a 10A breaker opens in higher value of its nominal.
https://upload.wikimedia.org/wikiped...it_Breaker.svg
If we used a 16A breaker for 1.5mm2 line, protection of that line would be compromised, because we could pull 22A from it for example and the 16A breaker would never trigger!
*To know the max current with precision we would have to take into account the wire material (copper, aluminium), if it is multicore or singlecore cable, other cables that run near it etc.Last edited by goodpsusearch; 11-24-2017, 01:59 AM.
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Re: Replacing unknown NTC Thermistor in Corsair CX400
Originally posted by goodpsusearch View PostYou must love FSP power supplies
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Re: Replacing unknown NTC Thermistor in Corsair CX400
I'm not sure how many of you are old enough to remember, but some 25-30 years ago all manufacturers of electric appliances were supposed to add the schematics of the whole thing to the manual sold with the device (be it a TV, a stereo or even a freezer and so on). This also included the part list, which made repairing a breeze once the defect was correctly identified.
I'm not sure when this habit (or were it laws/regulations?) ceased to operate but I'm amazed that at least in a highly regulated place like the EU the IT manufacturers are allowed to get away with selling stuff without even publishing the relevant schematics on their websites... [rant off]
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Re: Replacing unknown NTC Thermistor in Corsair CX400
Originally posted by Stefan Payne View PostPS: Please look for the protection chip.
Is it a HY-510N?? Seasonic seems to like this garbage protection IC...
Even in the 8pin world there are way better ones that support OCP on minor rails and/or UVP on +12V...
I can also confirm that the new NTC thermistor has also blown (don't know when that happened)
I'm starting to think there is something pretty strange going on with this PSU. I also noticed that the PC it was in, had been doing a DMI /ESCD data update on almost every POST. With a different PSU in, it's not doing that any more.Last edited by Agent24; 11-30-2017, 02:32 PM."Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHorn
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Re: Replacing unknown NTC Thermistor in Corsair CX400
I think I spoke too soon. ESCD update still happens on this board even with a different PSU. Probably a BIOS bug instead maybe. The board only has F2 BIOS (Gigabyte) with nothing newer out yet.
But I still don't know why the new thermistor blew. What is the likely cause? Underrated component? Seems funny both blew quite hard though. Maybe there is a fault in the PFC circuitry?"Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHorn
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Re: Replacing unknown NTC Thermistor in Corsair CX400
I had a look at this again yesterday, after being annoyed by it and leaving it in a corner.
The design is such that the primary filter capacitor is initially charged via a diode direct from the bridge rectifier, and the NTC. The APFC circuitry is effectively in parallel with that diode, between the bridge and the NTC, and so there is no way a fault in the APFC could blow the NTC.
The only logical conclusions then are that for the NTC to blow, there must be either 1) a serious fault in the SMPS primary side, or 2) shorted mains filter capacitor. Since neither of these seem remotely true, I suspect that the NTC failed from old age.
This would fit with how my replacement NTC also blew, considering it was a used pull from a dead and much older PSU board.
I have now fitted a brand new EPCOS B57235S509M as the NTC. Time will tell what happens..."Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHorn
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Re: Replacing unknown NTC Thermistor in Corsair CX400
Is there a relay or triac across this thermistor? In some PSUs the thermistor gets shorted out after some brief time interval. This allows use of a higher value of thermistor, to achieve a lower value of inrush, but whose hot resistance is so high that it would fry were it not shorted by the relay or triac. If there is such a relay or triac that failed, that might account for the frying of the thermistor.PeteS in CA
Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
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Re: Replacing unknown NTC Thermistor in Corsair CX400
If the APFC MOSFET shorted out it will blow the main fuse, or the NTC, and may take out the bridge rectifier with it also.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Re: Replacing unknown NTC Thermistor in Corsair CX400
Originally posted by PeteS in CA View PostIs there a relay or triac across this thermistor? In some PSUs the thermistor gets shorted out after some brief time interval. This allows use of a higher value of thermistor, to achieve a lower value of inrush, but whose hot resistance is so high that it would fry were it not shorted by the relay or triac. If there is such a relay or triac that failed, that might account for the frying of the thermistor.
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