APC UPS1400 ( 1400VA / 950W ) rack mount (schematic needed)

Dacflyer

Solar Enthusiast
I have an APC UPS1400 ( 1400VA / 950W )
I been using this in a small solar set up for a while in constant battery mode. been doing great for over a year now.
But the other day i noticed the fan has died. But it's not the fan,. the circuit that controls the fan is my issue. I have tried to bug it out, but i'm running into a brick wall.
Would anyone happen to have a schematic on this unit ?
If i cannot fix the issue soon, I'll most likely just hot wire the fan..But i'd like to fix it properly, if possible..
 

perpetual

Solar Enthusiast
@Dacflyer
Hope this helps, fan drive schematic on page 8, not sure if this is for the pedestal or rackmount unit
 

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Dacflyer

Solar Enthusiast
@Dacflyer
Hope this helps, fan drive schematic on page 8, not sure if this is for the pedestal or rackmount unit

Thanks buddy. A big star for you... much appreciated help..
I pretty much traced things out.. and i'm bout right on track
I do not understand the use of the D48 ( why not just use a bigger diode )
and Q42 and Q44 are also paralleled. I cannot make out where the drive signal comes from going to the base of the 2 transistors.
can you clarify ?
If desperate enough i could just redo things and let fans run off of a thermal switch..
 

perpetual

Solar Enthusiast
You are correct, the two D48 diodes in parallel could be replaced with one larger diode, but it was probably cheaper using parallel 1N4148 diodes instead of a larger model plus the added redundancy of having two devices
same goes for Q42 & Q44 (probably paralleled for redundancy)

The fan drive signal comes from IC11 pin 4 (SH2, C-1) which means schematic 2 (page 2) grid position C - 1

Edit:
Also the fan drive schematic on page 8 shows two 2pin fan headers J10 & J10A
So looks like two fans could be used hence why the parallel diodes & transistors
 
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Dacflyer

Solar Enthusiast
Ok , Problem found,, I dug out my sillyscope, I have determined that the 2 transistors are open..
the base is 162mv when off and 5v when on. And I can jump the emitter and collector and the fan will turn on..
So, I'm gonna find a beefier single transistor to replace it with..

J10 is where the header is, J10A has a spot for a header, but it's blank. and they are on opposite sides of the board.
I'd like to relocate the thermal probe, it's just in ambient air right now. I was thinking to put it on the inverter heat sinks,
or in that area at least.

I wish i had a 2 wire thermal controller for a fan control handy.
I'll have to make / build me one. use an OP amp, so the fan is either on or off at my selected temperature..
I'd like a variable fan if possible, but i can't find a decent easy circuit..
The ones i did find weren't very analog friendly, and so the fets overheated. transistor types aren't so bad, but most things are PWM
and too many parts to use..
 

Dacflyer

Solar Enthusiast
ok,, repairs are made... replaced both transistors with a single transistor.
I used a generic ECG393 this is strong enough to run 6 fans..lol

during spare time at work, I will start on a small thermal control circuit to control some other fans
I'm using to help keep the transformer cool.. so they cycle on off as needed..
 

Dacflyer

Solar Enthusiast
Ok, i tried to find me a ready made fan controller, didn't find any to suit my needs, so i made my own, basically an op-amp and a few discreet parts, and now i have something pretty good.. If interested I'll post a schematic... NOTE >>-----> All parts are from my junk box, parts are not critical, just so long as you're close to needed values..
 
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