Belkin F5C520 UPS...

I don't like servicing without a schematic, either. But considering that the LM317 and a 2N2222A are a lot cheaper than your time, why don't you just replace them and see that happens?

As the output of the LM317 is well below what it ought to be, the odds are pretty good it's defective.

: I am looking for a schematic for a Belkin F5C520 UPS.

: In case you are wondering and/or can help, output voltage for charging : the battery is only coming out at 2.4 volts with the battery unhooked : from the circuit.

Finding a schematic is doubtful.

Don't assume that 2.4v reading without the batteries is incorrect. Most UPS's don't use a constant charge voltage, it's pulsed on/off on a duty cycle depending on the current battery charge level.

Unless you tried a fresh set of batteries, it's not really worth the time to look at the circuitry.

That is the rub, likely the cost of them is going to be 50-75% of the replacement value of the ups to begin with.

If you really think it has something to do with a LM317 and 2N2222's, those are nickel/dime parts (if that much) but I really doubt they have anything to do with the charging circuit.

Belkin already discontinued that model, they have larger capacity ones for under $100. Most places are selling the battery for the 520 at $41-$49 plus shipping.

It's just not worth it.

-bruce snipped-for-privacy@ripco.com

Thanks for the reply, you are correct it will not put out 14 volts without the battery being hooked up to it, my other two UPS'es would put out voltage whether or not the battery was hooked up so I thought this one would act the same.

This USP is discontinued as you already stated, even the owner's manual posted online lists the software as Windows 95/98, the battery is available for $20 to $40 depending on where you go, there is a local place I get UPS batteries from I'm going to see how much they want for it when they are open and then I will decide what to do.

I already told the owner that the UPS was going to be disposed of so I'm off the hook in that regard.

Thanks again.

-Landon

Firstly, Belkin like the rest of them, will not give out any schematics or service information.

Before you tear in to the UPS, put on a new set of batteries! The chargers in these are a pulse charge system with a very sophisticated load sensing. If the battery is slightly out of spec for the charger, it will not charge the battery.

I have some Belkin and APC UPS's in our place, and they all do the same effect that you are describing when the batteries have to be changed.

--

Jerry G. ======

I am looking for a schematic for a Belkin F5C520 UPS.

In case you are wondering and/or can help, output voltage for charging the battery is only coming out at 2.4 volts with the battery unhooked from the circuit.

Nothing appears to be fried on the circuit board, no bulging capacitors, etc. It has what appears to be an LM317 based voltage regulator system, this is more is less where my trouble shooting is going to start.

So far I have figured out that the 317 has 23 volts on the input pin, ADJ and OUT have approx 2.1 volts on them. There are what appears to be three little tiny resistors attached to the ADJ pin, and a 2N2222A transistor is somehow hooked it the ADJ as well, it tests fine.

Not sure where to go from here without a schematic.

Thanks,

-Landon

Thanks for the reply.

I never would have even opened mine but the "Check Battery" light wasn't on and it wasn't putting out the correct voltage like my other two UPS' do so I figured it was just a low output voltage problem. Guess I learned something new today.

There is a local place that I get UPS batteries from, not sure if they are open tomorrow or Tuesday due to the holiday, either way I left a message on their voice mail to call me, if its cost effective I will get a new battery for it if not its various parts will be recycled and the battery hauled to the hazmat dump which luckily is only three miles from my house.

-Landon

Well, the battery was only $22 so I went ahead and bought it, could have bought it for $19 online but the shipping probably would have killed the $3 savings.

But anyway... the unit has been charging for over 24 hours I have nothing plugged into the UPS outlets, right after I unplug the cord from the wall the voltage instantly drops from 122 VAC to 102 VAC and then it starts beeping and the voltage starts slowly dropping like it is supposed to. The user manual says that the output is supposed to be 120 volts +/- 5%

Also, if I disconnect the battery from the wires the battery is reading

14 volts, and oddly the "On Battery" light is on even when it is charging. And finally, the output voltage now stays at 14 volts without the battery being plugged in.

Any suggestions?

Well, this UPS has taken a turn for the weird...

Found out that if I plug a PC into it (just the PC not the monitor) the output voltage will go up from 102 volts to 118 volts AC, which was close enough to 120 that I figured it would be ok. Then I plugged another PC into it and the voltage wavered for a moment or two then shot up to 130 volts.

Sounds like a regulator has gone out, I'm almost wondering if this has anything to do with that LM317 I originally mentioned in my first posting.