Replacing unknown NTC Thermistor in Corsair CX400

[Agent24]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Indeed, there is certainly no relay and I've not seen a Triac in there either.

[momaka]

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.

I doubt you would find a circuit that "exotic" in a budget 400 Watt unit.

[R_J]

Re: Replacing unknown NTC Thermistor in Corsair CX400

I found this atx schematic and it uses a SCK-2R58 ntc, this is a 300watt supply

[budm]

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.

[PeteS in CA]

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.

[Agent24]

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...

[Agent24]

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?

[Agent24]

Re: Replacing unknown NTC Thermistor in Corsair CX400

PS: 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...

Yes. I can confirm mine uses the HY-510N also.

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.

[Adrian_]

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]

[momaka]

Re: Replacing unknown NTC Thermistor in Corsair CX400

You must love FSP power supplies

Hehe, they're not all bad. Actually, I've seen some older FPS units that are very nice. Have pictures of two units that I need to upload here - probably the best built FPS of all time.

[goodpsusearch]

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.

[Stefan Payne]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Actually it is more like:
10A for 1.5mm2
16A for 2.5mm2
20A for 4mm2
25A for 6mm2
32A for 10mm2

Hm??
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...

[goodpsusearch]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Yes, they would.

Normal Ratings are B16 breakers wich allow only 3-5 times the nominal value.
Wich means that everything over 48A is crap and trips breaker (hello Sirfa!!)
And max is 80A.

However there is also the possibility to install a C16 breaker that allows 5-10 times the nominal value (=80-160A), but depending on the length of the cable it's not always possible.

And they are expensive as hell. At least double the price of a normal B16.
I've paid about tripple what a normal B16 breaker whould have cost....

That sounds like much but a B16 breaker cost as little as ~2€.
And I've paid ~9€ for one (Hager) C16...


First 1,5mm² copper wire is the norm here in Europe (German)
That is somewhat between AWG15 and AWG16...

Second: Normal breakers for that (as far as I know) is 16A with the B characteristics.
Although I've heard that 13A is the new norm and 16A is only allowed under certain conditions.

Third: In some regions like the old Communist Germany 10A are also used - with Aluminium wire. I can't say anything about that, never seen it, that's only what I've heard...

Actually it is more like:

10A for 1.5mm2
16A for 2.5mm2
20A for 4mm2
25A for 6mm2
32A for 10mm2

The problem is Corsair HX is almost the same thing as CX---M, just with bigger and more components. Design-wise, they look too similar and HX still has the same crappy flat heatsinks that the CX---M has. To me, that's a definite low-ball in quality. Even a Gold rated 700W PSU will dissipate over 70 Watts of heat. Divide that into three heatsinks, and you get 23W on average per heatsink - which is a bit too much for a fin-less heatsink.

You must love FSP power supplies

[Stefan Payne]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Well, on that note, I'm no fan of CWT's nor Seasonic's soldering.

It seems to be dependent on what you want and willing to pay for.
Corsair units doesn't seem to be great in that regard, even for CWT Standards.
If you know where to look for (hand soldered joints + primary daughterboard), you find some ugly parts...

Though Bitfenix Whisper M seems quite well made, as does my CWT GPS one.

On that note, everyone can take a moment to learn from Delta here, though Enhance and Seventeam are to be honorably mentioned as well.

Sirfa also seems to be quite good.

Astonishingly, HEC doesn't do too bad a job either...
FSP is solala.

CWT seems to be a hit or miss, depending on what you want and willing to pay for...
They can be quite good, they can be quite bad...

Anyways, all in all, I don't find Seasonic to be any worse than CWT. And I'll take Delta any day over these two.

Who doesn't...
But with Delta, if they put 1 cent too much Solder on one unit, they loose something around 100k or more a day. They are just that large.
That's why it makes sense for them to have the best of the best soldering there is - not too much, not too little...

For smaller manufacturers it doesn't matter that much...

[momaka]

Re: Replacing unknown NTC Thermistor in Corsair CX400

That's what you think.
But try talking to eTailers. If you have connections they tell you a completely different story.
Some of them seem to be very unhappy with Seasonics Return Rate...
And here are also reasons for that.
For example some people seem to be very unhappy with Seasonics Fans. And also coil whine could be a reason for that...

No, that's what I've seen working for a big national brick-n-mortar retailer here (no, not Worst Buy).

Seems that CWT-built Corsair PSUs come back the most. Doesn't matter if it's the cheap CX---M platform or the "premium" HX. (Though I will note that Corsair and EVGA made up most of the PSU sales where I worked, so it is natural to see more of those come back). But EVGA, on the other hand, is doing okay, minus their low-end 400-500 Watt units, which seem to stop working for no reason.

As for Seasonic coil whine - yeah, I've seen a few do it quite badly, but the PSUs seemed to be working fine otherwise. Actually, my Antec EarthWatts EA-500 has some pretty nasty coil whine too. But hey, at least it works. Just needed a recap. I'll take a recap job any day over a mystique design that quits for no reason one day (which seems to happen a lot more often to CWT).

Yes, but why talking about lower end/budget units when talking about reliability?!
That should be a job for high end units...

Well, just because I am looking at a low end unit doesn't mean I should expect it to break after a year or two of use. I mean, it's okay if they used cheap caps in there to save on costs and it's okay if it's not the most efficient PSU or the most quiet one. But just because it's cheap doesn't mean it shouldn't still be fairly reliable. If I didn't care about reliability at all and just wanted something very cheap, I'd grab a Deer / Allied.

The X/P Series is something you should compare to Corsairs HX Platinum series. Maybe RMx Series.

The problem is Corsair HX is almost the same thing as CX---M, just with bigger and more components. Design-wise, they look too similar and HX still has the same crappy flat heatsinks that the CX---M has. To me, that's a definite low-ball in quality. Even a Gold rated 700W PSU will dissipate over 70 Watts of heat. Divide that into three heatsinks, and you get 23W on average per heatsink - which is a bit too much for a fin-less heatsink.

And have you taken a look at the Focus Reviews @ Jonnyguru?
One of them had some solder problems...

Well, on that note, I'm no fan of CWT's nor Seasonic's soldering. I still have cuts from last week from handling that 850 Watt ThermalTake of mine. The S12II left my hands bleeding in a similar way while I was recapping it. Untrimmed leads + crummy solder joints tend to do that, though. On that note, everyone can take a moment to learn from Delta here, though Enhance and Seventeam are to be honorably mentioned as well.

Anyways, all in all, I don't find Seasonic to be any worse than CWT. And I'll take Delta any day over these two.

[Stefan Payne]

Re: Replacing unknown NTC Thermistor in Corsair CX400

They are probably doing that because they don't like to take a good design and turn it into garbage with bad components, just because some re-branding company asked them to in order to keep costs lower.

No, I wasn't talking about "CHeaping out", I was talking about new ideas and other changes...

But there is a third factor - reliability. On that front, I don't think CWT is doing so well. Again, they are OK, but not great. Meanwhile, most Seasonic designs are pretty rock solid in terms of lasting a good while.

That's what you think.
But try talking to eTailers. If you have connections they tell you a completely different story.
Some of them seem to be very unhappy with Seasonics Return Rate...
And here are also reasons for that.
For example some people seem to be very unhappy with Seasonics Fans. And also coil whine could be a reason for that...

I was doing a PSU replacement for someone a few months back, and they said their PC is critical, so they didn't care much about the price on a new PSU, as long as it was reliable. The PC was a pretty basic one, with a single mid-range GPU and mid-range CPU - nothing power hungry. Yet, the Corsair CX that was in the rig was dead. It had little dust in it, so it wasn't that old.

Yes, but why talking about lower end/budget units when talking about reliability?!
That should be a job for high end units...

With reliability in mind, I grabbed what I thought was the best choice - a 650W Seasonic made by... well Seasonic. It was quite expensive for a 650W PSU - more than Corsair's and EVGA's 1000 Watt units. But then again, it also came with 10 years warranty. To have that kind of warranty, you can be sure as heck the PSU must be done well.

Yes, and??
Other manufacturer do have something similar. If you want to pay of course....

But then again, there are many mentions of people on the Interwebs that report something like random shutdowns and such with Seasonic high End units (X/P Series)...

Looking through the vents of that 650W Seasonic, everything was packed to the brim. It was actually just as heavy as a 1000W PSU. The primary had HUGE caps. Not that non-sense 400-500 uF I saw in my CWT-based Corsair CX750M and the 850 Watt Thermaltake Smart M series. Oh, and it had an 80+ Platinum rating, too.

Yes, but why do you compare a high end unit that's always better than a lower end with a lower end unit where you have to meet some fixed price points to sell that unit. If you go over it, it doesn't sell at all anymore...

The CX Series is something you should have compared to the S12II/M12II series.
The X/P Series is something you should compare to Corsairs HX Platinum series. Maybe RMx Series.

So in the end, you get what you pay for... (well, if you are lucky, as always. )

Yes, and that's why you should compare low end with low end and high end with high end and not make some kind of cross comperation.

With the low end, especially the "full Japanese" ones, you have to sacrifice on Bulk Capacitance. Or fan Quality, or both, to get to the price point you want.

Take a look at be quiets Pure Power for example. Rather cheap caps, but bulk capacitance is in the right area for ofline UPS. And the fan is quite good as well.

Now take a look at some competitors...
Bulk Capacitance way off but 'Japanese' Bulk cap...
And/or fan not as good.


With higher end units like Bitfenix Whisper M, Corsair RMx and similar you have more room for better components than on low end units...


And have you taken a look at the Focus Reviews @ Jonnyguru?
One of them had some solder problems...

[momaka]

Re: Replacing unknown NTC Thermistor in Corsair CX400

I think Seasonic as a contract manufacturer is the worst one of all...
I really don't understand why they are regarded that highly on the Interwebs.

CWT is a real contract manufacturer. You want something, you get what you paid for. That's it.
Seasonic does not do that.
They only do what they have, don't allow any other changes than the modular PCB. And also other stuff you don't want to know.

If the CX430 was cheaper than the CX400 is something you have to ask someone else. Its said that Seasonic is one of the more expensive manufacturers but also they aren't as good as people on the interwebs say they are.
CWT can do decent stuff and their soldering on the main PCB is rather good, but when it comes to handsoldering it can become rather ugly.

Just because Seasonic is terrible as a contractor doesn't mean they are a bad designer.

They are probably doing that because they don't like to take a good design and turn it into garbage with bad components, just because some re-branding company asked them to in order to keep costs lower.

Still, there is a reason why so many people let their stuff be manufactured by CWT.

Most likely, that reason would be just price to performance ratio.
CWT PSUs perform OK and cost a very reasonable price. But there is a third factor - reliability. On that front, I don't think CWT is doing so well. Again, they are OK, but not great. Meanwhile, most Seasonic designs are pretty rock solid in terms of lasting a good while.

I was doing a PSU replacement for someone a few months back, and they said their PC is critical, so they didn't care much about the price on a new PSU, as long as it was reliable. The PC was a pretty basic one, with a single mid-range GPU and mid-range CPU - nothing power hungry. Yet, the Corsair CX that was in the rig was dead. It had little dust in it, so it wasn't that old.

With reliability in mind, I grabbed what I thought was the best choice - a 650W Seasonic made by... well Seasonic. It was quite expensive for a 650W PSU - more than Corsair's and EVGA's 1000 Watt units. But then again, it also came with 10 years warranty. To have that kind of warranty, you can be sure as heck the PSU must be done well.

Looking through the vents of that 650W Seasonic, everything was packed to the brim. It was actually just as heavy as a 1000W PSU. The primary had HUGE caps. Not that non-sense 400-500 uF I saw in my CWT-based Corsair CX750M and the 850 Watt Thermaltake Smart M series. Oh, and it had an 80+ Platinum rating, too.

So in the end, you get what you pay for... (well, if you are lucky, as always. )

[Stefan Payne]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Nonetheless, I can't help but note that your CX400 looks very much like the Season S12II platform.

Because it is.
Corsair had to take some shit when they broght the CX430 based on some CWT plattform instead, because people think the CWT plattform is inferior to the Seasonic one...

I'm hoping it will be fairly reliable if it is based on Seasonic.

If that's the case it all depends on the component choice and how well all that stuff is calculated and implemented.
The Manufacutrer of the Plattform doesn't hav much to do with it...

I think the first run of Corsair's PSUs were quite good, then quality fell away when they switched to a cheaper OEM?

That's what people say.
But I don't believe it anymore these days.

I think Seasonic as a contract manufacturer is the worst one of all...
I really don't understand why they are regarded that highly on the Interwebs.

CWT is a real contract manufacturer. You want something, you get what you paid for. That's it.
Seasonic does not do that.
They only do what they have, don't allow any other changes than the modular PCB. And also other stuff you don't want to know.

If the CX430 was cheaper than the CX400 is something you have to ask someone else. Its said that Seasonic is one of the more expensive manufacturers but also they aren't as good as people on the interwebs say they are.
CWT can do decent stuff and their soldering on the main PCB is rather good, but when it comes to handsoldering it can become rather ugly.



Still, there is a reason why so many people let their stuff be manufactured by CWT.
And there is a reason why there aren't any new Corsair, be quiet and Cooler Master PSU made by Seasonic these days.


PS: 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...

[Agent24]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Yes, it does seem like the SCK 054 is a fair choice. It hasn't exploded so far anyway, and the PSU seems to be operating normally.

Thanks for the offer. I'm hoping it will be fairly reliable if it is based on Seasonic. I think the first run of Corsair's PSUs were quite good, then quality fell away when they switched to a cheaper OEM?

[momaka]

Re: Replacing unknown NTC Thermistor in Corsair CX400

Does anyone know the value of the thermistor used in the CX400, or can advise on how to pick a suitable replacement? I did find a thread on the Corsair forums: http://forum.corsair.com/v3/showthread.php?t=112161 but nobody answered.

Well, looks like you found your solution more or less.

Nonetheless, I can't help but note that your CX400 looks very much like the Season S12II platform. In fact, the layout looks almost like an exact copy of my Antec Earthwatts EA-430 and EA-500 PSUs. So if you ever need any parts numbers off of those, let me know.