UPS beeping continuously

[Dannyx]

Re: UPS beeping continuously

did you fix the shit soldering yet?
if not then your just wasting your time.

Pff that put a grin on my face, the way you called it "shit soldering"

Anyway, I guess I did reflow most of the components. I believe I'm close to tracking down the issue: something's not right in the battery level monitoring - I have no idea ATM how it determines it, but when it DOES decide to turn on, the battery level indicator bars on the LCD display jump up and down randomly before the thing finally shuts down, so it's either a cold joint somewhere still, or a component (resistor?) became out of spec. Trying to track down how it senses the battery level now. Such a pain with these SMD resistors since you can't check them in circuit...

[stj]

Re: UPS beeping continuously

did you fix the shit soldering yet?
if not then your just wasting your time.

[Dannyx]

Re: UPS beeping continuously

I made another discovery: I did the transformer thing with a series lightbulb and I get 9.5v on the output. Without the bulb I get 12.5v with one pair of primary wires (black and yellow) and 15.5 with the other (black and blue), which makes me wonder how it charges the batteries with that little. Anyway, we can assume the transformer is working.

[Dannyx]

Re: UPS beeping continuously

Only because a relay clicks, it doesn't mean it is good. You have to check the contacts to see if they make a good contact too.

Agreed, but only after the system actually turns on that relay, otherwise contact resistance is irrelevant since the contacts don't touch anyway. The two relays that the AC input has to travel through (one for L and one for N) do no have a have an NC position to check. I got your idea otherwise.

The overload LED can come on also if the UPS doesn't output correct voltage.

Which is not going to happen anyway with no transformer connected though I tried it with the transformer and same thing. I measured the continuity of the transformer and I got readings on both the primary and secondary. I'm fully aware that's not how you measure a transformer, but I wanted to check for thermal fuses or completely open windings. Just because I got continuity doesn't mean the transformer operates correctly. I was thinking of powering it straight off the mains to ensure I actually get output on the fat output leads, which I'm expecting to be somewhere around 26v, since it goes straight to the batteries using the body diodes of the FETs - no charge circuit as far as I can see, so it shouldn't exceed the charge voltage normally.

Measure the current consumption of the UPS with whatever it is doing at this point.

Where would I measure this ? At the batteries ?

[CapLeaker]

Re: UPS beeping continuously

Only because a relay clicks, it doesn't mean it is good. You have to check the contacts to see if they make a good contact too. The overload LED can come on also if the UPS doesn't output correct voltage. Measure the current consumption of the UPS with whatever it is doing at this point.

[Dannyx]

Re: UPS beeping continuously

I didn't go that in-depth (though it would've been easy), because I couldn't hear them coming on at all, so I checked the coils first: 12v from bench supply on either coil contact, paying attention to the polarity of the freewheel zener diodes so as not to short the power supply. I heard them clicking, the were good I reckon contact resistance would come into play once I hear a relay turning on but stuff not going through, so I didn't do that just yet.

[stj]

Re: UPS beeping continuously

Relays are good - I tried each of them and they work.

how did you test??
you have to check contact resistance both open and closed.

[Dannyx]

Re: UPS beeping continuously

That heatsink holds a 12v regulator whose input is in series with that large ceramic resistor....I wonder why a regulator needs such a large resistor on its input. I'll try replacing them - not like I have anything to lose.

Relays are good - I tried each of them and they work.

[kc8adu]

Re: UPS beeping continuously

replace the caps near the heatsink in the center.
it runs hot and probably baked the caps dry.

[CapLeaker]

Re: UPS beeping continuously

did you check them relays yet?

[stj]

Re: UPS beeping continuously

when you have bad connections to connectors and relays it could be anything.

[Dannyx]

Re: UPS beeping continuously

Not too many large components on this thing...just those FETs. Guess it's worth a reflow nonetheless. Normally, it should fire right up in battery mode when it detects no AC. It could be that it's not detecting the transformer (no AC output), but I don't hear any relay clicking, so that power couldn't make it to that sense resistor network on the right (third photo) even if it DID work...something else is interrupting the "startup" sequence, whatever that might be....

[stj]

Re: UPS beeping continuously

btw, after caps, micro-cracks around pins of large or heavy parts or connectors is the most common fault on stuff.

[stj]

Re: UPS beeping continuously

it's taken some knocks, there are a lot of micro-cracks in the soldering.

[Dannyx]

Re: UPS beeping continuously

Tried hitting the board with some hot air but didn't change anything. Strangely, today the problem is consistent: a continuous beep with FAULT shown on the display...

[petehall347]

Re: UPS beeping continuously

as far as know line interactive will raise or lower mains voltage accordingly . and if gets too low it will switch to batteries .. ones i have had have a dip switch for parameters .or is software controlled ..
warm up the caps see what happens ...

[Dannyx]

Re: UPS beeping continuously

Have you checked to see if there is a blown battery fuse?

It does react to the battery being connected to the terminals, so there is power going into it. Having a look at the underside of the board also shows us that there's no other way for current from the battery to get into the board but through the fuses. For a second I thought there might be some hope in what you suggested, like current flowing into a sense line but not to the main FETs, but no...

I imagine it got hot when he brought it in because those busted batteries were drawing a lot of current, since otherwise the transformer is not doing any (major) work when on mains beside trickle-charging...unless, from what my brief knowledge is telling me, we're talking about a line interactive UPS which this clearly isn't.

[Curious.George]

Re: UPS beeping continuously

Point is: what are some of the common failures in UPSs that would cause them to behave like this, as if the battery is low or it's being overloaded ?

APC units will squeal incessantly if the battery is dead. Have you checked to see if there is a blown battery fuse?

Note that the UPS shouldn't be "hot" with no load if on mains power.

[Dannyx]

Good day folks. This is going to be a general discussion, since it's a rather particular issue with a rather particular device that not many people are going to have around, but the basics may still apply.

I've got an UPS (called "SPS Pro", whatever) which won't turn on but beeps continuously when you connect its batteries or plug it into the mains. When you apply mains, the display does come on with all the segments illuminated like it's initializing something, but then begins beeping and the display goes out (sometimes, but not always, accompanied by an "overload" indicator). The weirdest thing about this is that I replaced the batteries in it yesterday (takes 2 of them in series for 24v) and it worked perfectly on the bench with nothing plugged it. My colleague then took it to the customer where it was to be installed and on its way there it somehow broke down and when he arrived and tried plugging stuff in, the thing went crazy and he had to come back with it....heavy thing BTW

I'm suspecting bad caps (pun intended) This thing likes to get hot....VERY hot...in fact when I first got it to replace the batteries, it was SO hot inside of it that the transformer inside was impossible to touch, despite having spent around half an hour in transit turned off, from the client's site to our shop, so I can imagine those caps don't like that, especially 24h a day for the past year or so ! The batteries were completely cracked, bulged and leaky...it was a freak show. Still, it appeared to work immediately after replacing the batteries, and I may have a theory: it was still warm when I replaced the batteries, so the faulty cap(s) might have still been semi-functional, you know how you heat them up slightly and that SOMETIMES tricks devices like TVs and main boards and other stuff to turn on ? After a while sitting on the bench, it cooled down, the caps failed for real this time and here we are...I might try heating it up again gently just to see what happens. Batteries are full, at around 25v in series, so no issues there.

Point is: what are some of the common failures in UPSs (upsS...is there such a word ? ) that would cause them to behave like this, as if the battery is low or it's being overloaded ? Nothing's blown, of course, at least not visibly. Certainly none of the 8 transistors - I checked those, plus I doubt it would've looked so pristine if one of those went Could it be considered a "software" issue ? Is it really that smart ? I see a micro on there, but that could be for the display for all I know.