🚀 go-pugleaf

Jean-Christophe wrote:
> On Apr 25, 2:28 am, Sylvia Else <syl...@not.at.this.address> wrote:
>> Jean-Christophe wrote:
>>> On 24 avr, 15:42, Sylvia Else <syl...@not.at.this.address> wrote:
>>>> Jean-Christophe wrote:
>>>>> On Apr 24, 6:14 am, Sylvia Else <syl...@not.at.this.address> wrote:
>>>>>> My longserving SOLA 325 UPS suddenly quit yesterday.
>>>>>> Anyone have a sevice manual, or schematic, for this model?
>>>>> http://www.eserviceinfo.com/download.php?fileid=19986
>>>> Thanks, but that appears to be from the 305 model, which seems to be
>>>> different.
>>> Uh, sorry ... not close enough ?
>> Seems to be different, though it's useful in showing the likely general
>> configuration.
>>
>>
>>
>>
>>
>>
>>
>>>> In the mean, time I've discovered that the reason it's completely dead
>>>> even on battery is that the 40A fuse to the battery has blown.
>>>> Disconnecting the large transformer and shorting out the fuse allows the
>>>> display to light, go through its initialisation cycle, and then indicate
>>>> a fault.
>>> I strongly suggest that you replace the fuse, because the
>>> unknown fault might make things worse, and you may
>>> blow up the whole unit ( which could solve the problem )
>>>> The failure of the fuse wouldn't explain why the device won't run while
>>>> on mains power, so the fuse is presumably a symptom of something else.
>>> Sure it is. Sorry I didn't  find the manual.
>>> What is the error/fault message on the display ?
>> "UPS fault" indicated by a continuous beep from the unit.
> 
> Of course ... sounds a bit like Monty Python to me.
> 
>> Given the number of transformer leads that I have unplugged, this is
>> hardly surprising.
> 
> Since you don't know the cause of the original failure,
> are you sure I won't happend again ?

I've commented elsewhere in this thread that I've identified a couple of 
power switching FETs which are defective. One of them is shortcircuited, 
across all three terminals, which would certainly have blown the fuse.

Of course, that just pushes the question down a level - am I sure that 
whatever blew the FETs won't happen again. And of course, the answer has 
to be no.

These transistors only switch when the UPS is in backup mode. At other 
times, they're not switching, but their drains are connected to the 
secondary of a transformer that has mains applied to the primary. The 
failure could be attributed to a power spike, though I have to note that 
the UPS is plugged into a surge arrestor, and nothing else in the house 
seems to have suffered.

> 
> Did a short-circuit occur on the output(s) of this UPS ?
> 

No.