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Article #1624

Re: Understanding a split-mode power supply.

#1624
From: Phil Allison
Date: Tue, 06 Jan 2009 06:05
54 lines
2846 bytes
 "Stupider than Anyone Else"

>
>>>>
>>>>> As for whether I could substitute a 6.8, maybe I could, though I'd 
>>>>> have trouble getting one that has a 350 volt rating.
>>>>
>>>>  **   Huh   ??????????
>>>>
>>>> No need for that whatsoever.
>>>>
>>>> In operation, the resistor is not subjected to more than a few volts.
>>> As I commented earlier, if the switching transistor fails by shorting 
>>> out, then the resistor will blow. After it's blown it'll have 340V 
>>> across it.
>>
>> ** Irrelevant.
>>
>> Once it has fused, the resistor  will be OPEN circuit.
>
> Which just means it won't conduct unless the voltage across it exceeds its 
> insulating properties.


** No,  it  WILL  be open circuit to the voltage that caused it to fuse.

Cos the fusing behaviour will not cease until the part becomes open circuit
in the given situation.


>> The voltage across the break can be thousands of volts.
>
> So you say, but where's the evidence?


** You came here for the advice of folk with experience of electronics,  cos
you have none.

That advice is based on many decades of ACTUAL experience, in my case.

If you simply replace the fusible resistor in the PSU with a similar part,
then it will work as well as the original one did.

BTW:

The maker's max voltage rating relates to a functional resistor -  not a
blown one.

There is a HUGE amount of electronics YOU have no clue about.



.....   Phil
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From: "Phil Allison" <philallison@tpg.com.au>
Newsgroups: sci.electronics.design,sci.electronics.repair,aus.electronics
Subject: Re: Understanding a split-mode power supply.
Date: Tue, 6 Jan 2009 17:05:29 +1100
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