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Article #1608

Re: Understanding a split-mode power supply.

#1608
From: Sylvia Else
Date: Mon, 05 Jan 2009 03:04
56 lines
3490 bytes
legg wrote:
> On Mon, 05 Jan 2009 09:28:54 +1100, Sylvia Else
> <sylvia@not.at.this.address> wrote:
> 
>> Phil Allison wrote:
>>> "No legg to stand on "
>>>
>>>> This assembly was designed to fail in a safe manner - no fire,
>>>> explosion or shock hazard was intended to result from a single fault
>>>> resulting in the fusing of the emitter resistor. However, this does
>>>> not mean that the repaired unit will meet the same standards. The
>>>> events that occurred may have affected the safety isolation of
>>>> magnetic isolators in such a way that a second similar event may not
>>>> be as benign.
>>>
>>>
>>>  **  Jesus Christ  -
>>>
>>> get fucking real you asinine fucking WOG  WANKER !!
>>>
>>> The  WHOLE  damn AC unit is metal encased,  installed &  MAINS  earthed 
>>> !!!!
>> Leaving aside the abuse, I confess this was my sentiment as well. And 
>> not only that, neither the outside nor inside units even get touched in 
>> the normal way of things.
>>
>> The entire board could go up in flames, if it were inflammable, and 
>> still cause nothing more than a bad smell. Since it's outside even the 
>> resulting fumes wouldn't be a threat.
>>
>> Sylvia.
> 
> I see that specific poster's dialog in your response, only. His actual
> postings get filtered autiomatically here.
> 
> The unit is unlikely to go up in flames, for good reasons. 
> 
> As a technician, you'd be advised to follow industry standards in
> repair of any line-isolating assembly. One doesn't always know the
> n'th reason why something was done.
> 
> A hipot is not impossible to arrange, locally, if you don't have the
> equipment yourself.
> 
> RL

My test repair with a non-fuisible resistor and an NPN transistor from 
my stock seems to have worked (rather to my surprise), so I'll have to 
source a fusible resistor now.

I'll take your comment about a hi-pot on board, though in fact I've only 
worked on the high voltage side of the system - the transformer hasn't 
been touched. Still, I suppose insulation breakdown in the transformer 
could be implicated in the original failure.

Sylvia.
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Date: Mon, 05 Jan 2009 14:04:15 +1100
From: Sylvia Else <sylvia@not.at.this.address>
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Subject: Re: Understanding a split-mode power supply.
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