[rescue] Sun T5240 power supply failure?

[Rjtoegel]

I would also add, replace any cap that appears to be bulging at the end.  If
they are still functioning, they will soon be an open circuit or a NED (noise
emitting device).

Bob

On Feb 29, 2016, at 16:24, John Hudak <jjhudak at gmail.com> wrote:

> Sparky eh?  Cool.......
>
> Well you didnt say if the machine died or not after you saw the sparks.
>
> Things can cause sparks that may not harm the PS or the boards.
> These things include:
> Build up of dust, moisture, 'critters' - Generally what happens is that a
> bridge is formed between two voltage lines, e.g. the 120/220 vac lines
> inside the PS, or 5VDC to GND.  Once a bridge is formed, it creates a short
> circuit and the electrical energy will ionize the bridge (if it is weak
> enough), clearing the bridge and the PS continues to function.  If the
> bridge is large enough - e.g. capable of carrying the electrical current,
> then the weakest link in the current path will overheat/vaporize causing
> sparks (and in most cases, releasing the magic smoke..lol).  If this
> happens, the PS needs to be repaired
>
> Other things that can cause bridging (aka shorts) include failing
> capacitors, resistors, transistors, diodes, etc.  If the failure mechanism
> is a short, the inrush of current will cause them to vaporize, and
> depending on the path, may  take out other components.  The reasons for the
> failure include power surges, power cycling, and component degradation over
> time that may cause increased current draw, resulting in the weakest link
> in the path failing.
>
> Of note, there was a well know capacitor failure problem in the 2006-2010
> timeframe (IIR the dates correctly) where the mfg produced bad quality
> capacitors that after about 2-4 years, depending on use, would burst.
> Quite anazing to see.  Many PC MB along with Apple all in one MB were
> affected by the bad  caps. The MB in one of my PCs had the electrolytic cap
> explode, sending aluminum paper pieces all through the machine, and the
> only thing left on the MB were the two leads soldered to the board...quite
> cool...
>
>
> One needs to do some troubleshooting of your PS to determine what has
> happened.
>
> One of the common activities done on older machine is to 're-cap' the
> PS....e.g. replace all the electrolytic capacitors with new ones.
>
> good luck
> J
>
>
> On Mon, Feb 29, 2016 at 3:21 PM, Steven M Jones <smj+rescue at crash.com>
> wrote:
>
>> On 02/28/2016 23:13, chris t wrote:
>>> One of the power supplies on my new T5240 just shot out a bunch of
>> sparks,
>>
>> "New?"  New to you, but not new from the factory, or NOS? I think this
>> model was introduced around 2009...
>>
>> Did you have contact with this machine during it's prior service life?
>> PSUs are not immortal, and if you weren't working with it before, you
>> don't know what (ab)use it may have seen.
>>
>> "Sometimes people just explode. Natural causes." -- Repo Man
>>
>>
>>> Anyone else see this sort of thing happen?  I'm pretty spooked, to be
>>> honest.
>>
>> I haven't had a PSU go sparky, but I've certainly had them fail. And as
>> Peter mentioned, there are sometimes transient or permanent wiring
>> issues cropping up.
>>
>> You might want to try:
>>
>>  * using a multimeter to check levels at the outlet(s)
>>  * putting a UPS and/or line conditioner between T5240 and outlet
>>  * using a Kill-o-watt or similar to monitor power draw from machine at
>>    next power-up
>>
>>
>> Hope that helps,
>> --S.
>> _______________________________________________
>> rescue list - http://www.sunhelp.org/mailman/listinfo/rescue
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