Melted Plastic On Wires (PSU)

By Jaf
Jun 11, 2006
  1. Hey all.

    The other day I thought I could smell burning plastic. So I shut down the comp and had a look. The two wires shown below have melted their covering plastic. They go to a front case fan (zalman zm f1 at full speed).

    Melted Plastic

    The wires come from this connector which comes from an Antec True480(PGB) PSU. These two wires then finish off at a 3 pin male fan connector. This then goes into the 3 pin female fan connector from my zalman zm f1.


    Could anyone please tell me why the plastic has melted. Obviosuly the wire itself is too hot which is melting the plastic, but why is that wire getting too hot? I have only been able to smell burning plastic once. The wires now don't seem hot at all, and the computer and front case fan works fine. But it is bothering me, something must have gone wrong?

    In case you need em my specs are

    amd athlon xp 2700+ (2.16ghz)
    1gb ddr 333 pc2700 ram
    msi 6777 mobo socket A
    msi 6800gt agp gpu
    120gb seagate hdd
    dvd rw
    dvd rom
    antec true480 (pgb - uk version)

  2. DragonMaster

    DragonMaster TS Rookie Posts: 327

    Is the gauge smaller on these than the ones of the fan?
    (In fact, what's the gauge of the wires)
    How many watts is the Zalman using?
    If the contact is poor at one end or the other, the wire is making more resistance, and then heating.
  3. kirock

    kirock TS Rookie Posts: 1,221

    If those wires burned, which btw, are 16 awg, then they took a whole hack of current for an extended period of time. I would guess in the order of 10-15 amps. This is way way too much for the Zalman to be drawing normally, so either the fan is dieing or you have a short on the mobo near that connector.

    I would be very careful about running the PC before having this problem fixed or you could kill the PSU and maybe cause damage to other components when the PSU dies.

  4. Jaf

    Jaf TS Rookie Topic Starter Posts: 52

    The zalman zm-f1 is brand new and seems to be working fine. There used to be an antec pro case fan but it was getting a bit noisy so I swapped it for the zalman. I really can't remember when the burning smell appeared but I am leaning more towards the idea that the plastic melted when the antec was in. Actually, it's coming back to me, I had just cleaned the cpu heatsink and fan. I turned the machine on and after 20 secs I smelt the burning. I crapped myself at first thinking it was cpu related as I had just been messing with the heatsink and areas around it. I must admit, af a first look I didn't spot anything. It was later on in the day when I came to fit the new case fan I spotted the melted plastic. I went ahead and fitted the zalman. 3 days on and i keep checking the wires straight after a shutdown of the comp after a long running. The plastic feels fine, hardly even warm. However I am still worrying at the moment I can't relax. At least I know the zalman didn't cause this.

    Btw, how can a short on the mobo be identified and how are they fixed.
  5. DragonMaster

    DragonMaster TS Rookie Posts: 327

    Since the fan is connected to a Molex, it can't be a mobo short. Maybe the Antec fan getting noisy was because it was worn and maybe there was a short somewhere in the motor, and it was using too much current. The wire shouldn't heat at all normally. Just change your adapter for a new one and you should be fine.
  6. kirock

    kirock TS Rookie Posts: 1,221

    Ok, my misunderstanding, I thought it was a case fan connected to the mobo not via a free standing connector. So as Dragon pointed out it can't be a short on the mobo and was most likely caused by the old Antec case fan drawing way too much current as it's bearing failed. I don't think you have a problem any more and hopefully you caught it before the antec fan caused any real damage to the PSU.

    Prob best to keep an eye on the connector just to make sure it didn't take a beating too from the overcurrent and start to overheat. Not likely as a good working case fan usually only draws about 0.3Amps, so that shoudln't stress it at all.

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