UPS Fault

[Michael C]

Hi Everyone,

I have a UPS which seems to have a component in it that is not stable. I
have a 40W light bulb hooked up to it and when I first turn on the ups the
light bulb brightness will jump around rapidly (when running on batteries).
If I switch to power then relays inside the unit start clicking in and out
approx 2 times a second and the brightness of the lightglobe jumps up and
down in incremements as the relays click. After the unit warms up the
problem completely dissappears. I could just use it but I'm worried if the
problem does appear when it is warmed up it might damage the computer or
even start a fire. Does anyone know what the likely culprit might be and how
I might test for it? I know the basics of electronics and what the basic
components do. The model is a Sola 325 1000VA

Thanks in advance for any replies,
Michael

 

[terryc]

Hi Everyone,

I have a UPS which seems to have a component in it that is not stable. I
have a 40W light bulb hooked up to it and when I first turn on the ups

The model is a Sola 325 1000VA

So, you are worrying about a 40W load on a device designed for 1,000Watts?
Try it with a 100W or 150W or 250W and see what happens.

(Yes, I know VA=/= watts).

 

[Sylvia Else]

Hi Everyone,

I have a UPS which seems to have a component in it that is not stable. I
have a 40W light bulb hooked up to it and when I first turn on the ups the
light bulb brightness will jump around rapidly (when running on batteries).
If I switch to power then relays inside the unit start clicking in and out
approx 2 times a second and the brightness of the lightglobe jumps up and
down in incremements as the relays click. After the unit warms up the
problem completely dissappears. I could just use it but I'm worried if the
problem does appear when it is warmed up it might damage the computer or
even start a fire. Does anyone know what the likely culprit might be and how
I might test for it? I know the basics of electronics and what the basic
components do. The model is a Sola 325 1000VA

Thanks in advance for any replies,
Michael

I'm pretty sure the SOLA 325 models use basically the same circuit. My
comments below are based on my recent memory of repairing a SOLA 325 750.

When this UPS is running on the mains, its live output is a tap off its
transformer primary, which is being used as an auto-transformer. The
relays are just switching between taps.

When it's running off the battery, it's a simple inverter circuit.

What stands out as being common between the two is an LSI chip - there's
only one. I think I'd be inclined to remove it from its socket and
reseat it.

You will disconnect the batteries (as well as the mains) before you take
the UPS apart, of course? !

Sylvia.

 

[Michael C]

Observing the pcb for signs of stress or smoke when doing this (and
having one hand on the power button) might be a good idea.

Thanks for the replies everyone, I will have another look at it in the next
few days and see what I can find.

Cheers,
Michael

..