MS 6340 - Hissing

[alk]

First let me give you the specs of this system:

MS 6340 - Mini ATX motherboard
Athlon 1GHz TBird
384MB RAM
nVidia TNT2 RIVA 32MB
235W HIPRO power supply

Problems began a few months back whilst playing a fairly inensive game for the specs of this system - Day of defeat (Half life mod). The system suddenly rebooted, and since then has been unable to boot up without freezing for any more than 10 minutes.

I've stripped the system down to ram, cpu, and gfx and booted into bios and left it there to see if it freezes, and it does.

What I noticed was a strange hissing which seemed to cease as soon as the system froze. I also monitored the voltage off of a molex connector with a multimeter, and noticed the voltage drop by about 0.1Volts when the system froze.

I investigated the hissing further by removing the ram, and gfx, so I only had a psu, mobo, and cpu (with hsf). I unplugged the fan on the cpu, and the when powered up, the hissing was coming from somewhere on the motherboard.

The only problem is that none of the capacitors look in bad shape, and they are all at near perfect 90 degree angles to the mobo.

Any clues?

PS. I know someones already posted a 6340 thread, so mods, you can move this to that thread if you find it appropriate to do so.

[alk]

Re: MS 6340 - Hissing

Just opened up the PSU and had a look inside to reveal at least 4 bad caps. Pretty much explains the irrational behaviour of the system, the hissing and the readings I was getting on the multi meter. Thanks anyway to you guys, the information on your homepage and forums has been of great help to me!

If a new power supply doesn't do the trick, I'll maybe be posting on here again!

[davmax]

Re: MS 6340 - Hissing

Well done. Looks like you are on to the problem. Power supplies can be a real trap.

[alk]

Re: MS 6340 - Hissing

Thanks. I've just ordered a 300W power supply from ebuyer. Its only about £6-7, but the reviews seem good, and people are having no problems using it with systems of similar specs to mine. Hopefully it'll do the trick, considering the old supply was only 235W anyway.

[linuxguru]

Re: MS 6340 - Hissing

BTW, most HiPros are fairly well-built, and certainly worth a recap. If you recap with decent low-ESR non-aqueous series like Nichicon PX/PW/PJ/PM/PR/PS/PL, Chemicon LXZ, Panasonic FC/FK, etc. on the secondary, they should be OK for another decade or so.

I have three recapped 250W HiPros on a Northwood 2.6, an Athlon-64 3000+ and an Athlon Thunderbird-C 1400 respectively, and all three are now rock-stable Linux build machines.

[tazwegion]

Re: MS 6340 - Hissing

Just opened up the PSU and had a look inside to reveal at least 4 bad caps. Pretty much explains the irrational behaviour of the system, the hissing and the readings I was getting on the multi meter. Thanks anyway to you guys, the information on your homepage and forums has been of great help to me!

If a new power supply doesn't do the trick, I'll maybe be posting on here again!

Yeah, i was gonna' suggest the PSU (you were too quick)

I've had at least 2 'Yum Cha' generic 250w PSU's that 'hissed' on their way out, they were from Ipec propriety systems

[kc8adu]

Re: MS 6340 - Hissing

seems the latest hipro units pop caps faster than the old ones.esp the ones where the heatsinks form an arch over the transformer.caps not getting airflow and running hot or the crap caps just getting crappier?

[alk]

Re: MS 6340 - Hissing

Today I got the new power supply, and its not really made a difference. The system now runs fine without any disk drive attached to it, it stayed on a good 20-30 minutes in the BIOS. As soon as I try booting up with ANY disk drives attached at all, the thing gives up the ghost. The same hissing is apparant, and Im pretty sure its coming from the motherboard now. Somewhere north of the ziff socket. Could it be that a mosfet has failed???

[alk]

Re: MS 6340 - Hissing

sorry for double post, but could it be a torroid that is making this noise?

[gonzo0815]

Re: MS 6340 - Hissing

May be the bulged caps had harmed the caps on the board too. This is not always visible.

[Melfman]

Re: MS 6340 - Hissing

In case this helps anyone, I saw exactly the same problem recently (6340 unstable + hissing until crash).
Problem was a Nichicon 4700uF 6.3V HD series (sleeveless style) near the ATX power connector (C12 and C22 on ver:1 board). Wasn't bulged or askew at all, but was venting from the base. Had to clean electrolyte off the board as it had spread over a wide area
Temporarily replaced with a Nichicon 3300uF 10V PW from the spares bag + the board tests fine now (I'll do it properly one day ).

I'd swear the sound was the cap venting, but like alk said, there's a big inductor nearby that could have been whistling.

Melfman.

[Harvey]

Re: MS 6340 - Hissing

I too have seen this with MS-6340s. There are four large capacitors surrounding the CPU and they get the full blast of the heatsink/fan output, and as a result fail, generally with no obvious bulging.

The hissing sound is the inductors ringing, and its an early warning - change the caps before the MOSFETs fail.

[Melfman]

Re: MS 6340 - Hissing

Cheers for the heads-up Harvey, I'll give them a look next time I dig it out of the closet. I did notice those 4 are Panasonic HFA's on mine (other people have Tayeh) so it's possible MSI got wise to the problem.

The cap that failed on mine was on the power input side of the VRM, so I'm suspecting the PSU over-rippled it. Hissing sound stopped when the cap was replaced, so hopefully that means the Pannys are OK. No obvious problems in the PSU, but it's cheap and nasty so will swap. System's sat spare at the moment anyway, so not too urgent.

Melfman