SURT3000XL Won't Shut Off

[Anonymous user]

Hi, I have an SURT3000XL with Extended Battery Pack that I bought used (both). The ribbon that connects to the plastic APC interface board where all the LEDS are, was ripped off during shipping.
So I stripped the cable and soldered all 8 strands onto the board then connected the ribbon to the UPS. As soon as I did the fan came on, so the batteries must have had some charge left. I used to be able to turn the unit on and off normally using the buttons on the interface.

I connected the extended battery pack to the unit and connected them to mains for like 40 mins...and during this time the green battery LEDS ( the leds to the right-charging voltage percentage) kept rising till they reached 4 marks. I was happy, disconnected the UPS from the mains, turned the unit off, and called it a day.

Next day my friend comes and plugs the unit into the mains, he says that none of the buttons were working. The unit just turns on by itself, does the self test, and kept charging. When you press the OFF button instead of turning off it starts to show the orange battery LED as if I'm connecting a load to the UPS that's draining the battery. If you press and HOLD the off button, you get all red leds flashing/flickering (a very faint dimm flicker). It just won't turn off.

I built the RS-232 cable to have a look at what's going on, everything seems normal, no errors. I found out that one of the 4 batteries in the extended pack had a blown fuse (2 blown fuses on a PCB 500v 30Amp Fuse). So I disconnected the entire extended battery unit and put it aside. Using HyperTerminal I adjusted the battery packs from 2 to 1 and fully charged the two batteries that come with the UPS.
Took about 2.5-3 hours to reach 100%, Runtime= 300 minutes. Then I choose option no.2 (UPS Controls) then no. 4 in the menu (off the top of my head it was Start Runtime Calibration test or so) and left it overnight to do the test which I think it drains the batteries and recharges them..I had no loads on the UPS and it was connected to the mains all night.

Next day I came with the test done, and batteries 100%, runtime 300 mins, 0% power loads. So I hooked up 2 computers and a 12V battery charger to the UPS. the 12V charger was hooked to my car with the car's lights on/Blower/CD player...the car was drawing 27 amps @14VDC. This setup lasted for 33 minutes for batteries to drain to 1% and I started to get continuous beeps from the UPS. So I removed the 12V battery charger & I had another 20 minutes to run the 2 PCs. I then recharged the batteries again to 100%, Runtime=300mins.

So I suppose the UPS and batteries are healthy except that it won't turn OFF like it first used to....I double checked the ribbon cable, no adjacent pins were shorted, and ran a continuity test everything seemed fine.
I think it's the PCB of the UPS itself....Any hints, schematics, most common failure points on the PCB (relay, fuse..etc) would be MUCH appreciated.

Taking it to an APC dealer isn't an option as I'm from one of the so called 3rd world countries where the price of just one RBC44 costs more than the average citizen's annual income (due to crazy taxes/customs).
I'm an electrical engineer so I'll gladly take any risk and won't blame anyone one if 1 of the 2 huge electrolytic capacitors discharges into my face.

Sorry for the long post, and THANKS for having this GREAT forum.

[Anonymous user]

Thanks for your input guys! I'll tripple check on the cable and the 2 boards that it connects to from both sides. Will post my findings too 🙂

[Anonymous user]

It's been a very busy week at the workshop and I finally had a chance to give some TLC to my newly acquired APC.
I checked the cable many times, for connectivity or open circuits, it seemed fine but my soldering looked ugly. I must've been in a hurry or too excited, so I re-soldered it properly. I then inspected the LED board itsefl.The schmidt trigger IC (I think it was CD10406-BCM) under a magnifying glass. It had grey cracks on 2 legs so I just aimed the hot airg gun at it and let solder flow evenly.

I connected the unit, and it worked suuuuuperb. Even if the unit didn't work at ALL, I was still happy to own it (the PCB, connectors, components....great engineering!) and especially after building the serial cable and getting access to the cool menus...it's ALIVE!!! Board or no board it was already working 😛

Now I would still like to purchase that ribbon cable and the plastic black APC box that covers the L.E.D. board. A part no. and source online would be great guys.
I also intend to repaint or maybe powder coat the unit to remove all scratches...I might sound crazy but this is how I am when I get attached to something.

Thank you ALL!!!

[Anonymous user · Accepted solution]

Hi, I have an SURT3000XL with Extended Battery Pack that I bought used (both). The ribbon that connects to the plastic APC interface board where all the LEDS are, was ripped off during shipping.
So I stripped the cable and soldered all 8 strands onto the board then connected the ribbon to the UPS. As soon as I did the fan came on, so the batteries must have had some charge left. I used to be able to turn the unit on and off normally using the buttons on the interface.

I connected the extended battery pack to the unit and connected them to mains for like 40 mins...and during this time the green battery LEDS ( the leds to the right-charging voltage percentage) kept rising till they reached 4 marks. I was happy, disconnected the UPS from the mains, turned the unit off, and called it a day.

Next day my friend comes and plugs the unit into the mains, he says that none of the buttons were working. The unit just turns on by itself, does the self test, and kept charging. When you press the OFF button instead of turning off it starts to show the orange battery LED as if I'm connecting a load to the UPS that's draining the battery. If you press and HOLD the off button, you get all red leds flashing/flickering (a very faint dimm flicker). It just won't turn off.

I built the RS-232 cable to have a look at what's going on, everything seems normal, no errors. I found out that one of the 4 batteries in the extended pack had a blown fuse (2 blown fuses on a PCB 500v 30Amp Fuse). So I disconnected the entire extended battery unit and put it aside. Using HyperTerminal I adjusted the battery packs from 2 to 1 and fully charged the two batteries that come with the UPS.
Took about 2.5-3 hours to reach 100%, Runtime= 300 minutes. Then I choose option no.2 (UPS Controls) then no. 4 in the menu (off the top of my head it was Start Runtime Calibration test or so) and left it overnight to do the test which I think it drains the batteries and recharges them..I had no loads on the UPS and it was connected to the mains all night.

Next day I came with the test done, and batteries 100%, runtime 300 mins, 0% power loads. So I hooked up 2 computers and a 12V battery charger to the UPS. the 12V charger was hooked to my car with the car's lights on/Blower/CD player...the car was drawing 27 amps @14VDC. This setup lasted for 33 minutes for batteries to drain to 1% and I started to get continuous beeps from the UPS. So I removed the 12V battery charger & I had another 20 minutes to run the 2 PCs. I then recharged the batteries again to 100%, Runtime=300mins.

So I suppose the UPS and batteries are healthy except that it won't turn OFF like it first used to....I double checked the ribbon cable, no adjacent pins were shorted, and ran a continuity test everything seemed fine.
I think it's the PCB of the UPS itself....Any hints, schematics, most common failure points on the PCB (relay, fuse..etc) would be MUCH appreciated.

Taking it to an APC dealer isn't an option as I'm from one of the so called 3rd world countries where the price of just one RBC44 costs more than the average citizen's annual income (due to crazy taxes/customs).
I'm an electrical engineer so I'll gladly take any risk and won't blame anyone one if 1 of the 2 huge electrolytic capacitors discharges into my face.

Sorry for the long post, and THANKS for having this GREAT forum.