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Old 02-17-2021, 01:43 PM   #1
Dannyx
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Red face Anyone got a Scribd account to help with schematic ?

Good day folks. Long story short: I'm trying to get a schematic for a UPS which I can only find on Scribd, so if anyone has an account and is willing to help me obtain it, can you please visit this ?

Long story: this is the story of me trying to repair a Socomec Netys PR 3000 UPS. It runs on batteries but not on mains (so it doesn't charge them back). I noticed the charger SMPD area has a few blown resistors and a blown ceramic cap. (R70, R46 and C27). Right after replacing these, I also checked on the bottom and found R56 open - this one goes between the gate of the transistor and the switching IC U4. I replaced just the resistor and since the transistor was fine, I also assumed the IC was also fine. I tried plugging it in and after a few seconds, there was a loud bang, some sparks flew out and I was now left with a big mess on my hands: the components I had just replaced went pop again, this time also with some SMDs on the bottom AND the transistor itself......great >_>

So what happened ? I think U4 was bad to begin with and the transistor "locked up", as the open R56 would hint....I should've replaced the IC anyway.

I couldn't find any schematics going by the "Socomec" brand, so I looked up the board model (which I can't remember right now) and after digging through some russian sites, I ended up at that Scribd page and guess what: it's actually the same board - or at least close enough that I can follow. The sad part is that I can only see the first page - the rest are blurred in typical Scribd fashion. That's when I recalled a quirk I noticed on my phone: by navigating to the same page on my phone through Chrome, the pages are not blurred in the mobile version Sadly, every time I try to zoom in, the page freezes, so the best I could do was to quickly take some screenshots and piece them together to form a semi-complete schematic. It's missing quite a few lines here and there, so it's not perfect, but the charger portion which is on the first page is mostly clear, so I could follow along and rebuild the blown part.

There's one thing I don't understand: on the first page, BR1 is fed both by the mains AND the inverter output (the thick black lines going to BR1 are shown going through relays RY4 and RY5 and they're thrown either straight on the mains input on the far left OR the inverter output in middle of the page, where C25 is in the middle of that H-bridge). On the first page, Q13 is the dead transistor. It's got a CHG_PWM tag on its gate, which is going to U4 on the next page. The VCC pin of U4 has a 12v tag down the line. That tag comes from the third page from TX3 via D28 on the far right if I'm not mistaken. In turn, TX3 is run by Q43, which in turn is controlled by U6, which in turn gets +12v....from where ? If 12v is generated by U6 itself, how can it possibly sustain itself ? I see another transistor up top (Q42) which switches the BAT.V line to that same VCC pin, but isn't this over the rating of the IC to begin with? There's 6 batteries in series in this thing ! Interestingly, the UC3845 datasheet doesn't list a maximum input on the VCC pin, so maybe it's started by the battery voltage indeed. Even so, I see Q42 is switched by optocoupler U5 which comes on with mains present (I/P-L and I/P-N tags on the far left), so what happens when mains is NOT present ??? I see another tag ON_SW on the left via diode D31, but that leads to the last page which is a mess: too many lines close together so the screenshot turned out very poorly, so I can't tell where it's coming from

It would be nice to get the whole thing though, that's why I'm asking for help. Cheers guys.
Attached Images
File Type: jpg Soco1.jpg (356.3 KB, 4 views)
File Type: jpg Soco2.jpg (209.3 KB, 3 views)
File Type: jpg Soco3.jpg (245.0 KB, 3 views)
File Type: jpg Screenshot_20210217-203703_Chrome.jpg (411.4 KB, 3 views)
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Old 02-23-2021, 03:25 AM   #2
hasefroch
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Default Re: Anyone got a Scribd account to help with schematic ?

From what I can see, your analysis is spot on. The UC3845 starts up when the Vcc pin has 8.4V or more and this pin have a internal zener of about 36V, so it will start via D24, Q42 and R124 (autostart), o will run via ON_SW via R283 and a switch between pins 11 & 12 of CN7 (I assume in a front panel, this is not in the pdf)

Don't have an scribd account but found a online downloader, so I attached the schematic.

Hope this helps.
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File Type: pdf smart-winner-new-schematic.pdf (494.9 KB, 5 views)
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Old 02-23-2021, 04:34 AM   #3
Dannyx
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Default Re: Anyone got a Scribd account to help with schematic ?

Woohoo ! Just what the doctor ordered ! Thank man - sure beats having to mess around with Paint to stitch sh!t together ! BIG CHEERS ! We have a bunch of these UPS so this schematic is definitely going into my collection
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