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Today we’ll be taking a look at the Power Shield PSO-650 650VA Powerboard UPS, a 3+3 output UPS with surge/battery protection, phone line protection and USB for monitoring it on your PC. This particular unit failed because the 12V battery dropped to around 2 volts.

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By looking at the power cord is going to tell us that this UPS is going to be built down to a price because the cord comes straight out of the UPS itself.


We’ve got our main PCB on the bottom and a huge transformer on the top which isn’t glued or bolted down, it just sits there due to the pressure the case puts on either end when closed. We have a 250V 5A circuit breaker on one side of the case. The surge protected outputs have some big MOVs on them. There are a few things which could be a little better, the heat shrink may have been too big that it’s pretty easy to move around and they left in an extra wire like it was meant to go somewhere else (not that it matter too much as the terminals screws are exposed anyway). The transformer is a 1065SP-2-V8/ E186x40.

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Some of the transformer taps go to the Shori S3-12 relays which I’m guessing are used for the automatic voltage regulation that’s used in case of under/over voltage. There looks to be a bodge wire on the bottom board and lots of flux left over plus it seems that two jumper connectors on the board had wires soldered into them but then cut later on. There’s 2 automotive 4A red fuses in parallel, we’ve also got an 7805, an 317T and 4x STD65NF06 N Mosfets on board. The PCB date code is 7th week of 2008.

1. Holtek 8bit Microcontroller
This MCU was really hard to read the label, it has 192 byte of RAM, 4Kbits x 15 of EPROM, 2 counters, 9bit ADC with 20 I/O lines. Running from a 12 MHz crystal.


2. Cypress USB Microcontroller
12 MHz CPU with 128 bytes of RAM and 4KB of EPROM, running from a 6 MHz crystal.


3. ST Quad Opamp


And that’s all.

One Response to “Inside the Power Shield 650VA Powerboard UPS”

  1. TRL says:


    I love naked pics of electronics! 🙂

    LM324 is used to control AVR’s relay. Basically, this UPS (like all line-interactive UPSs) has an internal AVR that takes care output voltage. If voltage is way out of standards, then inverter starts and takes care of this.


    P.S.: I have a 650VA AVR at home with the same Shori S3-12 relays and I need to change them because got broken. I’ll look for OMRON perhaps.

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