Nexus 4090 Whining

[Brian75]

Hello,
First post... love this forum already. Great resource guys! I'm completely new to this and had no idea there were so many bad caps out there. To the chase:

Computer started taking multiple front switch attempts to power up. Switch... wait... switch again. Sometimes taking 5 minutes to finally boot. About 3 weeks go by and backlit fan controller slowly fades to blank over days... then suddenly one day gets bright again (4 pin molex 12v?). Then PC starts turning on by itself. Looked inside, mobo has blown caps around CPU and 4 pin connector. Replaced them with Rubycons from here. Mobo runs faster and more smoothly now. NEATO!

HOWEVER... noticed high pitched whine coming from PSU. Nexus 4090 about 5 years old? Entire system always entirely disassembled and cleaned thoroughly at least once every 6 months (including opening and cleaning PSU internals).

Narrowed the whine down to one of 2 larger transformers. Pitch does not change when transformer is prodded. Here's where it gets interesting...

PSU is switched on from back and begins to whine (barely audible) and comp won't power up using front switch. Then I wait for the whine to increase in pitch (2 to 5 mins?) until it gets almost inaudible and makes quick sizzling sound. THEN, system powers up from front switch. Whine returns consistently while comp is in use. Same thing with PSU disconnected from everything with Power Good line manipulated.

Now I know that the whine is coming from a specific transformer, but I'm wondering what the problem is. I do not think I see any bad caps inside and I looked under the board and although there is some brown in certain places (that stuff that assists in soldering?) all traces and joints appear fine. I can post pics eventually, but I'm trying to refrain from using that system as it is for work and my data is most important.

Also, I should mention... I added a 4th HD right before this happened (to Xfer data from another SATA drive in use). System is power hungry, but balanced out. DMM reads low on the +5v rail. I will also post voltages as the readings I got with my DMM perfectly match those given by Speedfan.

PSU: http://www.nexustek.nl/NXS-nx4090rea...ply400watt.htm

Any ideas for further diagnostics or does anyone know what this is? Any advice would be greatly appreciated! Thanks!

[370forlife]

Re: Nexus 4090 Whining

Most Nexus's are ATNG. Older ATNG loved Fuhjiyyu, which should be replaced on site.

[Brian75]

Re: Nexus 4090 Whining

Hello,
Thanks for the speedy reply! Looking at it now I only see Teapo, "RLS" (OST?), and Rubycon capacitors. Everything in this PSU is stock. There are a few pots in here too that I'm dying to tweak.

Anyway... would this whining coming from the transformer be a result of bad caps? If so, how would I go about diagnosing it? I do not see any bulging or anything that looks odd. Thanks again!

[seanc]

Re: Nexus 4090 Whining

I swear I saw a thread like this on Techspot.

OST fail without showing it.

One Antec EA-380 PSU I had looked fine on the inside, but whined and couldn't boot Vista. Re-cap and all is fine.

[momaka]

Re: Nexus 4090 Whining

Might be a problem with the 5vsb. Measure it with your DMM (hook it up between purple and black wire). Anything above 5.25v on 5vsb is out of spec. If you're worried about plugging your computer, unplug PSU from the motherboard and other peripherals, then plug PSU into wall and let it sit for about 20-30 minutes.
A quick search on Google showed one Nexus 4090 to have UL number E190414 (FPS Group). See what yours has and post it here. It should be a 6-digit number with an "E" prefix right under a mirrored "LR" logo. If I remember correctly, some of those FPS units had a 2-transistor 5vsb circuit. 5 years sounds about right for a circuit like that to start failing. Could end up killing the motherboard if such circuit really is present in your PSU and not immediately fixed. The only way to establish that, however, is with pictures. I cant' seem to find good ones one Google.
Also, do you see any areas inside the PSU on the circuit board that seem noticeably darker than others (particularly around the smaller transformer[s] or parts around the smaller transformer[s])?

[Brian75]

Re: Nexus 4090 Whining

Hello everyone.
Thank you so much for your help! Yes, looking at it now it have the UL number E190414. I was going to post pics... but I really couldn't find anything weird inside the PSU.

Rather than wait, I ordered and installed a brand new 520 watt Seasonic M12II Bronze. It's really nice... but this, my first time running it, still shows almost the exact same voltages in Speedfan. Everything seems to be in spec except for the +5v which is grossly out.

I took some screenshots so you can see what I'm talking about. The +5 is fluctuating every time Speedfan refreshes with or without a high load. Obviously, I may have to move this topic to MOBO Probs but I'd love to hear from you same people before I do. Like I said, I recapped all of the ones around the CPU. Could this be a messed up chip or a bad video card drawing too much current? Other than this issue, I am liking this Seasonic though. It's quiet! But now I'm worried about killing more components.

I don't think I saw any darker spots near the transistors. Would any of these types of tests help me troubleshoot with the new PSU? Ex: Testing the 5vSB with a DMM? Speedfan seemed to match up pretty accurately with the DMM on the Nexus.

THE PICS:
photobucket images removed.....uhgg...


With these voltages... would this thing even be running? I'm stumped. Any ideas? I'd like to keep this model board because I'm in the middle of a few projects and to reinstall all of my work software right now would kill me. Thanks!

[370forlife]

Re: Nexus 4090 Whining

Any software is very unreliable to tell voltages coming from psu's. Use a Digital Multimeter.

Seasonic psu is a excellent choice though.

[Oklahoma Wolf]

Re: Nexus 4090 Whining

Most Nexus's are ATNG.

FSP, actually.

[Brian75]

Re: Nexus 4090 Whining

Okay,
Well I just tested the voltages (on the new Seasonic) as directed on the loaded PSU in the system by back probing all rails. They all test perfectly at the back of the connector. Well within tolerence. Almost perfect actually. So this is a component problem on the mobo somewhere.

Any ideas where to begin? I see no blemished components or bad caps on the board (I already recapped the blown ones around the CPU), but I'd like to do my testing as quickly as possible as this is a nice new PSU and I do not want to damage it buy running a bad board with it.

Thanks again for your replies. I'd like to at least test before I do an entire recap, just to make sure that it isn't the CPU or a transistor or resistor or something. Any advice? Thanks guys!

[momaka]

Re: Nexus 4090 Whining

Not sure I quite get what the problem is here.
If it's just the motherboard/Speedfan reading the voltages wrong, you can ignore that. Many motherboards do this anyways. As long as your system is stable, you have nothing to worry about. Maybe recap the rest of the motherboard for the peace of mind if there are any other known bad caps left.

As far as the Nexus PSU - if you want to troubleshoot the whine, post some pics here. This will help us determine whether or not it has a 2-transistor 5vsb circuit - and if it does, the fix could be as simple as changing a few small caps that are usually in the range of 2.2uF - 100uF (so it should be cheap, too).

[Brian75]

Re: Nexus 4090 Whining

Hi,
Thanks for replying! Well, the problem is starting to happen again with the new PSU. Which is that my LED lit fan controller is now starting to get dimmer by the hour... which is one of the symptoms described above that I noticed before the Nexus started failing and whining, and before the caps around the CPU blew. So I'm thinking that this new PSU is going to get ruined like the Nexus.

I did the recap on the motherboard and tried disconnecting everything I could (PCI cards, HD's, memory etc.). I even swapped out AGP cards. The software reported voltages are so far out on the +5v that I'm extremely worried. It couldn't be the CPU itself could it? Are there any ways to test the +5v on the actual MOBO to try to find out if the voltages reported by Speedfan are correct? I have a feeling they are, and with that rail going down to as low as 1.89v I see this as a great concern.

I'll get some pics of the Nexus in the next few days and post them so at least there will be pics of the internals for this PSU on this site. Not sure if it was the MOBO that ruined the PSU or vice versa (or both), but it appears that the +5v on both PSU's is reporting low after hitting the motherboard. It tests fine at the connectors (for now). The only constant has been my USB keyboard and mouse, my system HD, and mobo and it's minimal components.

Thanks so much for the help guys... this is one of a few different electronics problems I'm dealing with right now and I'd be so grateful if I could get my work system up and running again. I appreciate it.

[seanc]

Re: Nexus 4090 Whining

Brian, as mentioned before, the voltage readings from software is totally useless.

I'd suggest hooking up a multimeter to the same rail that your led fan controller is on and watch the voltage. Perhaps your fan controller is just failing.