APC Back-UPS 1300 not charging battery

[Behemot]

Re: APC Back-UPS 1300 not charging battery

They will.

Probably transformer. This model is older so it has lower efficiency. May depend on the position, if the transformer is near the top it makes it hot, if its on the bottom, the air mixes and is not so hot there.

I'd definitelly replace the small caps, who knows in what shape they are and what it drives the UPS to do.

[sambul83]

Re: APC Back-UPS 1300 not charging battery

The transformer is on one side with batteries, and the PCB is on the other side, all major components separated by thin plastic walls. I noticed, the UPS heats up a lot more when its small upfront display is continuously lit, despite the vents are near the UPS back cover. It looks like the LCD activates some heat releasing circuit?

Do you replace all caps when repairing APC UPSs? There're plenty around the board, how its justified without signs of failure?

[Behemot]

Re: APC Back-UPS 1300 not charging battery

Experience.

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

Hi folks,

I came across your forum when looking for troubleshooting advice regarding my APC 1300 .... it simply doesn't charge the battery.

I read through this thread in detail several times, so hoping I understand it right.

When I opened the unit up, I noticed the main 22uF cap having bulging top. So I got a replacement (they didn't have 22uF 400V, but they insured me that 22uF 450V would work just as well, as long as I can accommodate the slightly taller footprint) and installed it in. But that didn't fix it. Basically the batteries are still not getting proper floating charge voltage.

I was trying to take some DCV measurements on the main cap and output cap .... I am not getting any DCV on the main cap, yet on the output cap I register 24.02V ...

BTW, if I remove the battery, and measure DCV against the leads coming from the unit, I get 12.02V ... right here I should be getting 27.6, correct?

If you can give me any advice, I'd appreciate it. BTW, I have the unit basically to experiment on, so it's not like the end of the world. I just thought it would be a good candidate to start some learning process.

Thanks

[Behemot]

Re: APC Back-UPS 1300 not charging battery

Replace the small caps too, use Chemi-cons KMG (they are usually GP; if you identify low-ESR cap, than use low-ESR one), not some no-name crap.

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

The problem is that the board has a lot of small caps, so replacing them one by one could lead to lottery type of fixing things.

At this moment, could you confirm that what I am finding even makes sense? Perhaps I am not doing something right (which is very possible) ... main cap measures basically 0V, yet output cap shows 24.02V? Doesn't that indicate problem upstream? To newbie like me it makes no sense that I have 0V on main cap, yet 24V on output cap?

Whatever is happening right now on the board, leads to 12.02V measured across the leads to the 24V battery, when the unit is plugged in ... less than half what it should be? Does that make any sense in respect to me not being able to measure any DCV against the main cap?

It's funny, we are both from CZ, end up talking English on badcaps forum ... :-) ... today's world is really tiny, eh?

[Behemot]

Re: APC Back-UPS 1300 not charging battery

Likely a bad contact, sometimes happens. Do you read 230 V AC on the input of the bridge rectifier?

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

The bridge rectifier on this board ... and I am using reference image from post 31 ... I see the four diodes, but where exactly should I measure 230V? ... I have seen the typical diode rectifier with two outside DC legs and two inside AC legs .... this one is above my pay grade ... LOL

[Behemot]

Re: APC Back-UPS 1300 not charging battery

Well, I cannot tell from the image, try tracing it from the fuse. Typical configuration is fuse, some input filtering, rectifier and smoothing capacitor.

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

The bridge is giving me fits ... just figuring out where the current flows from to ... learning curve I guess. So I have not figured out how to measure the input and output voltage of the bridge ... I mean I know that in theory when the bridge is a drawn box or inline with four prongs ... whole different ballgame when staring at the board.

Having said that, I think the rectifier has a problem. How do I know? With power off, measuring with my meter individual diods across in diode mode ... I get on 1 and 4 exactly the same 0.475V one way, OL when reversed ... on 2 and 4 I get only 0V both ways. Sounds like 2 and 4 are busted, conclusively?

Would that also sort of explain why I am getting only 12V, roughly half of what I should see on the way into the battery?

[budm]

Re: APC Back-UPS 1300 not charging battery

https://www.badcaps.net/forum/attach...4&d=1427166587
What DC Voltage do you have when measure right between the 2 legs of that main filter cap?

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

Something silly like -1.6mV ... regardless whether I switch the probes around.

[budm]

Re: APC Back-UPS 1300 not charging battery

Something silly like -1.6mV ... regardless whether I switch the probes around.

That is with UPS plugged into the AC outlets?
If that is the case you do not have the Voltage to run that SMPS section, so I do not know how you are getting the 12VDC at the cables (RED and Black) that go to the batteries.

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

That's right, with UPS plugged in. Yeah, it doesn't make sense at all. I am taking out the new main cap I soldered in, just to make sure I have a good connection. Since the cap is out from the circuit, what reading should I be able to get on the board where the main cap goes? In theory, with the main cap out, I should have zero voltage on the red and black wires going to the battery, correct?

[budm]

Re: APC Back-UPS 1300 not charging battery

With main cap removed you will be feeding the primary circuit with >200 VAC 100 Hz and that may damage the SMPS section due to the circuit EXPECTING about 330VDC for it to run, but Idoubt that is happening now, more likely that the rectifesr is not being fed with 230VAC right now.
i would find out for sure if the bridge rectifier is getting 220VAC feeding it or not.
BTW, you are getting that 12V dc without the batteries connected?

BTW, you need to trace out how those 4 diodes are connected in your board to from the bridge rectidfier circuit so you can see which are the points the AC is fed to them.
https://www.electronics-tutorials.ws/diode/diode_6.html

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

Yes it was 12V DC without battery connected (I have to start it with battery connected, but then I disconnected the battery and that's when I got 12V DC). With main cap out, there was nothing nothing on red and black to battery.

I will put the main cap back in now.

How do I measure the input/output of the rectifier? I am staring at those four diodes, but cannot measure any meaningful voltage regardless where I put the probes ... where do I measure exactly AC and where DC voltage, using your previous picture asa reference?

[yyzmxs]

Re: APC Back-UPS 1300 not charging battery

Missed your last paragraph ... yep that seems to be holding me back regarding the rectifier. Will have to keep reading, until I figure it out. Would the lowest D number generally be considered diode 1 and highest diode 4?

Thanks for your help, I appreciate it.