Re: Schematic or service manual for SOLA 325 UPS
- From: Sylvia Else <sylvia@xxxxxxxxxxxxxxxxxxx>
- Date: Thu, 30 Apr 2009 17:02:35 +1000
Sylvia Else wrote:
Sylvia Else wrote:Baron wrote:Reasonably likely perhaps, but not actually the case.Sylvia Else wrote:
Jean-Christophe wrote:On Apr 24, 6:14 am, Sylvia Else <syl...@xxxxxxxxxxxxxxxxxxx> wrote:Thanks, but that appears to be from the 305 model, which seems to beMy longserving SOLA 325 UPS suddenly quit yesterday.http://www.eserviceinfo.com/download.php?fileid=19986
Anyone have a sevice manual, or schematic, for this model?
different.
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.
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.
Sylvia.
It could just be fatigue !
I've found one of the switching FETs shorted, and another with unlikely resistances between the terminals. With both removed, it's possible to get the UPS to power up on the mains.
What threw me for a significant while is that it appears that powering up the UPS requires that the battery be present and providing power, but once the thing's powered up, it no longer needs the battery.
So looks like the FET shorted, and took out the fuse. Seems reasonably likely that replacing the FETs and the fuse will restore it to service.
Sylvia.
After I'd replaced the two FETs and the fuse, I turned it on. It went through its initialisation cycle, and then promptly blew again, quite dramatically, this time taking out all 4 FETs.
Guess this is one for the recycling bin :(
Sylvia.
I didn't quite get round to doing that. It bothered me that I couldn't discover the failure mode.
The output circuit is similar to that here
http://web.telia.com/~u85920178/power/invert1_00.htm
in that an FET (or two in parallel in the case of the SOLA UPS) drives each half of a centre-tapped transformer. However, the SOLA UPS is creating a modified sineway, so there is a significant period between one FET turning off, and the other turning on. The reverse diodes in the FETs are required to prevent very high voltages appearing when an FET is turned off. (Also note that it would seem to be a very *bad* idea to insert a diode in the battery circuit to protect against reverse polarity connection).
So it occurred to me that the two original FETs I left in the circuit might not have been in as good a state as I'd supposed. When I sourced replacement FETs, I bought 4, simply because of the mininum charge at Farnell. This meant I still had two. The circuit only needs four when it's driving a large load, so I thought I'd try one on each side. I also installed a much lower rated fuse, in the hope of protecting the transistors if things still went wrong.
But they didn't. It's actually working now. Perhaps the moral of the story is "always replace all the switching transistors".
Sylvia.
.
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- Re: Schematic or service manual for SOLA 325 UPS
- From: Sylvia Else
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