Back-UPS RS 800 Not charging

[canadaboy25]

Re: Back-UPS RS 800 Not charging

So at what test point that you are showing the 23VDC? How about the voltage on cap #3 which has 1.1V on it.

I have retested the voltages on the capacitors that you pointed out in this picture. All of the voltage tests were done with the replacement fuse connected while the board is on and connected to AC power. The batteries are also connected. These are the voltages I got from testing the two terminals on each capacitor with my multimeter set on DC volts.

1 - 22 vdc
2 - 6 vdc
3 - 3.8 vdc

It may also be worthwhile to add that the battery drops by 0.4 volts and starts dropping a considerably large amount faster if I disconnect the jumpers that are holding the fuse. The voltage also goes up about 0.4 volts and the speed of voltage drop also slows after I reconnect the fuse.

[budm]

Re: Back-UPS RS 800 Not charging

So at what test point that you are showing the 23VDC? How about the voltage on cap #3 which has 1.1V on it.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

you could have just soldered in the correct fuseholder.

Yeah I know that but I live by a small town and I was searching to just find the correct rating. This is just for testing.

[stj]

Re: Back-UPS RS 800 Not charging

you could have just soldered in the correct fuseholder.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

I got a fuse and soldered two wires to where the fuse came from and attached the fuse to the wires with cables so I could replace it if it blew.

There was no change in performance even with the new fuse. The fuse did not blow and you can see where the voltage is in the picture and it is slowly dropping.

[budm]

Re: Back-UPS RS 800 Not charging

You can use 2A 250V fuse in other from factor to test out the function first, this style of fuse can be found at Mouser or Digikey.

[Agent24]

Re: Back-UPS RS 800 Not charging

Yes I am in the process of getting my hands on an ESR meter so that is why I was wondering if that would be a fair enough test.

Going for the capacitance test first is more suited to non-polarized capacitors.

ESR measurement is a better test for electrolytics most of the time. But some can fail with reduced capacitance while the ESR stays OK! Also you can get excess leakage current problems too...

[canadaboy25]

Re: Back-UPS RS 800 Not charging

That is 2A 250V rating fuse. I am not sure yet as to where the charger circuit is, some of them use the SMPS for charging circuit, some of them use one of the winding on the inverter transformer (the transformer that is used for converting the switching 24VDC to 120VAC). I would try another fuse to see what happen, normally we would have used Ohm meter to check the resistance of each leg of the fuse (since we do not know which end of the fuse is the feeding side) to circuit ground, but we do not even know at this point which ground point is.

So why is this fuse in such an odd formation? I haven't some across many fuses like this before.

Would I be able to replace it with a "beaver tooth" fuse or one of those common cylindrical fuses to test the circuit?

Thanks

[canadaboy25]

Re: Back-UPS RS 800 Not charging

Yes, but only IF the capacitance has dropped. The thing with electrolytic caapacitors is that most of the time they fail due to high ESR, so you really need an ESR meter to do a proper test.

Yes I am in the process of getting my hands on an ESR meter so that is why I was wondering if that would be a fair enough test.

[Agent24]

Re: Back-UPS RS 800 Not charging

Would I be able to find the bad one if I just took them all off and checked the capacitance?

Yes, but only IF the capacitance has dropped. The thing with electrolytic caapacitors is that most of the time they fail due to high ESR, so you really need an ESR meter to do a proper test.

[budm]

Re: Back-UPS RS 800 Not charging

That is 2A 250V rating fuse. I am not sure yet as to where the charger circuit is, some of them use the SMPS for charging circuit, some of them use one of the winding on the inverter transformer (the transformer that is used for converting the switching 24VDC to 120VAC). I would try another fuse to see what happen, normally we would have used Ohm meter to check the resistance of each leg of the fuse (since we do not know which end of the fuse is the feeding side) to circuit ground, but we do not even know at this point which ground point is.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

Here is a picture of the fuse.

The rest was about as clar as mud to me

Both fuses are connected to the + battery terminal and from what I see they are connected to the 2 blue capacitors beside them. It looks loke the trace goes under the big transformer but I can't see where it goes. If it is nesicary I can take the transformer off and see where the traces go.

[budm]

Re: Back-UPS RS 800 Not charging

It can be that the fuse may have blown due to in rush current. What is the value of that fuse?
BTW, that yellow transformer is actually an inductor, L4.
Those two green fuses, one end is connected to the + of the batteries, the other end of the fuses should be connected to charging circuit, you will have to trace that connection out, it should be connected to the Cathode of the blocking (or rectifier diode of the charging circuit) diode of the charging circuit.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

I believe that fuse is for powering the SMPS for that small yellow transformer (not 100% sure), the secondary side winding of that transformer is connected to those two diode and that #3 filter cap. So there may shorted circuit in that area.

Would that mean that the transformer is shorted?

[budm]

Re: Back-UPS RS 800 Not charging

I believe that fuse is for powering the SMPS for that small yellow transformer (not 100% sure), the secondary side winding of that transformer is connected to those two diode and that #3 filter cap. So there may shorted circuit in that area.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

Here are the voltages of the three caps with the board running and one lead on each cap terminal.

1 - 23 vdc
2 - 5.8 vdc
3 - 1.1 vdc

The green beaver tooth fuses are also good. The round brown f3 was blown. I removed it from the board to be certan.

I am very sorry about the pics. Both of my good camera's were slightly knocked off a table. I hope these are better. If you need a picture of a very certain trace or something I will try my best.

And why were the ends of 2 doides to the right of the green fuses circled?

And the battey pack is 2 SLA's in series but they had shorted cells so now I just have some junker batteries with alligator clips on them

[budm]

Re: Back-UPS RS 800 Not charging

Can you please get better focus pictures, I also need the pictures of the bottom side of the board. Check the red fuse and voltages on those caps.
BTW, does it use two 12V batteries? From the spec it looks like just one 12V battery. And those two 30A green fuses are good, right?

[canadaboy25]

Re: Back-UPS RS 800 Not charging

chances are you would damage them during removal.
i wouldnt use them again anyway.

I removed 2 and they tested fine and I re-soldered them without a problem. The board is still working the way it was (useless).

[stj]

Re: Back-UPS RS 800 Not charging

chances are you would damage them during removal.
i wouldnt use them again anyway.

[canadaboy25]

Re: Back-UPS RS 800 Not charging

Would I be able to find the bad one if I just took them all off and checked the capacitance?

Help is apreciated