APC UPS units - troubleshooting

[Behemot]

Re: APC UPS units - troubleshooting

is that da BR1000I?

always post images TO THE FORUMS

only clean, focused and if possible, cropped to what's important (=no 5MB insane-resolution photos with half of your flat, but nothing really visible in them)

[foundups]

Re: APC UPS units - troubleshooting

Hi guys, I'm new in this forum.
Yesterday I found an APC Back-UPS 700VA (BX700U-GR) in the landfill.
The UPS is without battery (I ordered one).
I brought it home and immediately did some tests:

I connected the UPS battery lead to my bench power supply (setted at 13V).
The UPS seems to be working but the output outlets stays on only for one second (probably because my bench power supply in not powerful enough).

I connected the UPS to mains and I measured the voltage of the battery leads (battery not connected) and I measured 0.3V. Is this normal?

For the time being, until I have the battery, I cannot do any more tests....

Bye

[sam_sam_sam]

Re: APC UPS units - troubleshooting

Welcome to the forum —— thank you for trying to recover an item from the landfill

Post some very clear pictures of the circuit board front and back and we might be able to help you with it

“I connected the UPS to mains and I measured the voltage of the battery leads (battery not connected) and I measured 0.3V. Is this normal?”

That depends on what type of circuit it has for the charging circuit that is the reason for asking for the pictures of the circuit board

[foundups]

Re: APC UPS units - troubleshooting

Thank your for your response.
I attach some pictures I've taken.
I hope the pictures are sufficiently clear.

[Behemot]

Re: APC UPS units - troubleshooting

most of these cheap units usually don't power on correctly without working accumulator(s) connected

also do full recap, had this recently and it's same cheaped-out crap as all them chinese, several caps were beyond death (interestingly, it was quite baked around the buzzer, which seemed to got hot buzzing constantly)

[foundups]

Re: APC UPS units - troubleshooting

Hi, I received the new battery and I did some tests.
The output of the UPS stays on only for one second (same as powered with the bench power suppy)
I noticed in the PowerChute software that the UPS is overloaded, and the input voltage is totally wrong (458V).


And here's the warning that says that the UPS is overloaded


Any ideas on what components I could test?
I checked the resistors that form the resistive divider that is supposed to measure the input voltage, and they seem okay.
Then I will check the relays and larger capacitors.

[Behemot]

Re: APC UPS units - troubleshooting

I've now checked that soldering side of yours, it's also baked under the buzzer so the caps nearby will be toast as well

suggest either measuring them first, or doing full recap right away, having those caps dead could give ya plethora of different problems, which may include the behaviour you describe

other than that, check current sensing, R155 looks like it may be a current shunt?

not sure if service manuals/schematics are already available for these boards, it's still fairly "new"

[foundups]

Re: APC UPS units - troubleshooting

Hi, thanks for your response.
I noticed that the buzzer gets very hot, so I desoldered it.
You're right, I found a bad 22uF cap near the buzzer.

I measured R155 and is about 10 ohm, is a value a bit high for a shunt.
I think the current is measured through the CT1 transformer, the model is "460-0102C-Z LEI-8 ID30" but I can't find the datasheet.

[Behemot]

Re: APC UPS units - troubleshooting

dammit looks like me response was not sent

transformers rarely go bad and pretty much always are custom part, it's more likely some of them SMD components under it went bad, I'd say start with those diodes and resistors near the divider, around TP6 and 7?

[foundups]

Re: APC UPS units - troubleshooting

Hi, I was finally able to fix it!
I replaced almost all the capacitors with new ones, and it is working again. I still need to check if the battery is being recharged.

[Behemot]

Re: APC UPS units - troubleshooting

told ya

what did you do with da buzzer?

[foundups]

Re: APC UPS units - troubleshooting

told ya

what did you do with da buzzer?

I resoldered it on the board.

[csh]

APC SMT1000I, 2011 model, recap

Hi, I need some advice from the experts in the APC recapping department :-)
Got an older APC SMT1000I, 2011 model without fan that I would like to save if possible.
It came with 2 noname 7Ah batteries inside and some packing foam to fill the space, someone was creative :-)
It's working fine, tested it with light load, it charges batteries, passes self test, no strange behaviour.
Except for some quiet high freq hissing coming from a transformer compartment. Its hissing all the time, with or without battery, on battery...
Starts a second or two the after connecting mains power, after some relay clicks.
Don't know if hissing is normal for those APC units, but because of age, I would like to recap it before use.
It has 2 PCBs, large main one covering the whole top of the case and a smaller one that looks like some kind of PSU stuck in the back corner behind the transformer.
Right about where the hissing is coming from :-)
Main PCB is clean, no bulged caps, but as I was able to research, some small caps always fail on the APCs.
Small PCB is a different story, it was partially covered in some black soot in the region between the blue Y capacitor, transformer and two larger caps.
After treatment with isopropyl and a soft brush board is squeaky clean, no burnt components, just some darker spots from the heat on the back.
The plan is to replace all electrolytics :-)
I'm a hobbyist, not a pro, so I apologize in advance for my lack of knowledge :-)

My questions:
1. I was able to find the spec sheets of all the caps except the two SMD.
Pictures with markings and position attached.
Those have markings:

19
33
35V

and

D1
47
35Z

So I'm guessing 33uF/35V and 47uF/35V, general purpose?

2. The small PCB is bothering me, where did that black dust come from?
Nothing visibly blown, that protection cap is not open, it tested in circuit to something like 4.3nF which sould be in spec.
Diodes around it are not shorted. Could it be from the transformer?
3. This big cap at position 12 (C85) is EPCOS / TDK B41848-A7278-Z.
I'm having trouble at finding a replacement, any suggestions about that?
4.Anybody knows what is this smaller PCB for, some charger for battery or...?
5. Is there any way of detaching the black wire coming from battery connector in the back? It's the only one soldered directly to PCB :-)

Main board caps

Position    PCB mark        Brand / series   Values
1        C610          OST RLG       47uF 16V
2        C60           Uknown SMD     33uF 35V???
3        C606          Uknown SMD     47uF 35V???
4,7,9,10,11   C75,C35,C114,C100,C115 Lelon SSG      22uF 16V
5        C77           Lelon RGA      47uF 63V
6        C85,C102        IC RZM (Illinois)  330uF 25V
12       C85           EPCOS / TDK     2700uF 40V

Small PCB caps

C903      JNC JN472M (had some soot on it)
C917, C918   Jianghai CD 263 22uF 400V
C904      IC (Illinois Capacitor) 22uF 50V
C938      IC (Illinois Capacitor) 10uF 50V
C906      Jamicon TK 330 uF 5

0V