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Took a voltage surge to myapc ups bp420pnp knocked out mov 3 150 volt varistor replaced same unit does not trip the over load now but has no 120 vots to plug ins any ideas?

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It is also possible you have overloaded the unit, try reducing the amount of equipment plugged in. If that does not solve the issue, if this has no effect then its time to replace the ups.

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Posted on Apr 30, 2010


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Surge Protection

Here is a few tips to look for in a good surge protector:

1. Response time should be less than 1 nanosecond.

2. Energy absorption/dissipation should be at a rating of 600 joules or more.

3. Clamping voltage should be 330 V to 400 V. Generally, a clamping voltage more than 400 V is too high.

4. Get one with a an indicator light that tells you if the protection components are functioning. All MOVs (Metal oxide varistors (MOV) are semiconductors that protect electronic components and systems from transient voltages) will burn out after repeated power surges, but the protector will still function as a power strip. Without an indicator light, you have no way of knowing if your protector is still functioning properly.

5. Get one that has self test function. A button you push to test it.

on Oct 07, 2010 | Computers & Internet

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F04 indicates that "Clamp Short" it could be anything, but the word "clamp" reminds me of a varistor / MOV, which is the component that clamps short when there is a voltage surge condition and comes back to its normal state, an open circuit, when the voltage surge is gone. Sometimes it clamps short for good when it is hit by a large surge or just by absorbing and shunting to ground many small surges.

You can brain dead the UPS to check if that resolves the issue. This brain dead test helps to reset the internal circuit of UPS.

1. Disconnect any attached load.
2. Turn off the UPS
3. Unplug the UPS from the wall socket.
4. Disconnect the UPS internal battery.
5. Push and hold the "On" button on the UPS for 5 seconds.
6. Reconnect internal battery.
7. Plug UPS in to known good power source.
8. Turn the UPS ON.

If the same issue remains even after brain dead then you have to replace the UPS. This UPS comes with 3 years of warranty, if it is under warranty you can contact APC support at 800 555 2725

If the UPS is out of warranty then you can participate in APC Trade-UPS program. APC has Trade-UPS program where in you can trade your old unit and get a new unit with great discount. You will also get a return shipping label to ship the trade-in unit to us. You can refer to the below mentioned URL.

Mar 02, 2013 | APC Power Saving BackUPS Pro 1300

1 Answer

Varistor Repeatedly 'Blowing'

It might be external to your house some sort of industrial power usage causing spikes in voltage

Mar 26, 2017 | Exercise & Fitness

1 Answer

We get frequent power surges in this building and bought this to keep the computer on, but when the power surges the UPS says power overload and beeps until it is restarted.

The power overload warning should only come on if you have too much of a load plugged into the UPS. You may be close enough to the edge of the limit so the disturbance from a surge can be enough to trip the overload detector.

Your UPS is rated for 1200 Volt-Amps, so it can drive a maximum of 10 Amps at 120 Volts. Every piece of equipment should have a label with the maximum Amps or Watts on it. Add up the Amps used by the equipment plugged into the UPS/AVR sockets to make sure the total is less than 10 Amps. If the equipment label rates power requirement in Watts, divide that number by 120 Volts to get the amperage. One thing to read carefully is the label on the computer power supply. It is commonly rated in output watts, but that is not the number to use for this calculation. Since it is not 100% efficient, you need to look for the input Amps number.

If you are too close to the limit, move the printer or monitor to a surge-only outlet or consider replacing the monitor with a more energy-efficient unit. If your load total is less than 9.5 Amps, the UPS may have a defect in the power overload detection or internal voltage regulation circuits.

Sep 09, 2011 | CyberPower CPS1200AVR (CYPCPS1200AVR) UPS...

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Because of a power surge, i think i fried my tv, are there any safety procautions inside that might protect the tv, such as fuses, or would it just ruin the tv?

there are fuses and MOV's to protect for surges.
mov is metal oxide varistor, a resistor that shorts out when the voltage rating is exceeded causing the fuse to bluw.
always right after the fuse on the circuit board on the powersupply board

Mar 30, 2011 | Sony KDL32L5000 32 in. LCD HDTV

1 Answer

I Have a Maytag MAH7500AWW one of the MOV component on the mother board burned and the machine does'nt work anymore. I'm looking for the replacement piece but nobody has it around here, they all told me...

An MOV is a "metal oxide varistor". This is a very common heart of a surge suppressor, which can be used "across the line wires" to prevent harmful voltage spikes from adversely affecting equipment. Most of the time however, an MOV will sit idle in a circuit for years, then one day, it gives its life blocking a voltage spike. You use the equipment the next day like nothing happened. Everything works fine - until the next voltage spike.

Your MOV has already activated, and is no longer able to provide the protection it once had. As a result, the next voltage spike passes unobstructed by the failed MOV into the circuit ruining the circuit.

The problem is that the MOV never told you it failed. Many times, a number of MOVs are installed all at once - each one fails at each subsequent voltage spike. It could take years, decades or more before the last MOV fails - likely long after the warranty is over.

You can probably see that the failed 50 cent MOV isn't the problem any more. It was *before* the circuit failed, but you never knew it had failed. Now, the latest voltage spike fried the circuit and it will require wholesale circuit board replacement or labor intensive troubleshooting to locate and replace all the failed parts on the circuit board.

You're better off buying a used board or an entire used machine until you can fix this one.

I hope this helped you understand about MOVs, and that replacing this part will not restore the machine to working order.

Sep 09, 2010 | Washing Machines

1 Answer


you mean anything you turn on trips the breaker or just certain items,if so remove rear cover after unplugging unit or shutting off breaker, and look for what is called a m.o.v.(metal oxide varistor) its in there in case of a surge from lightning and has probably shorted(check w/ohmmeter) it protects the electronics side 120volt,but will drop out both legs of power on a tandem pole 120/120 volt breaker because of the way breaker is designed

Jul 08, 2009 | Kitchen Ranges

1 Answer

Sony de898 no sound

Could be an internal fuse blown but most later electronics use a special kind of resistor called a varistor. These devices are across the AC line and do nothing until the voltage difference between the two lines, hot & neutral, exceeds a certain voltage; this is typically ~200 volts for 120 service as in the US and higher for 220 service on most of the planet.
They are disc shaped, will be from 4-5mm (~ 3/8") to as much as 25mm (~1") in diameter and if ever zapped, they are charred and with chunks missing.  When their design voltage is exceeded, their resistance drops from near infinite to a few Ohms which then causes the fuse to blow. You can replace the fuse and choose not to replace the varistor but then you will not longer have even that minimal protection against spikes.
For folks in lightning-prone areas, the installation of a 'whole-house' surge suppressor is highly desirable, will cost ~$250 US and have an insurance policy against losses of $10-$25,000 US in case you still lose devices protected.       

Dec 19, 2008 | Sony STR-DE898 Receiver

1 Answer

GE Spacemaker Microwave Blown Fuse replaced still no power

If you measure across the varistor leads with it still in the circuit, you should measure around 100-300 ohms, which is the DC resistance of the primary of the low voltage transformer.

If you read infinity / open the primary of the low voltage transformer is bad.

If the varistor is bad, it will be shorted and usually it will be cracked or split. This is a much simpler way to test the varistor.

Have you checked the magnetron thermal cutout (TCO) (or thermostat if so equipped) and the oven TCO? These are the leading causes of a dead GE when the fuse is okay.

You didn't mention the model number. What is it?

Please reply back here if you still need help.

We're happy to help you. Once we have all your information and offer a final solution, we'd appreciate your thoughtful rating of our answer.

Jul 17, 2008 | Microwave Ovens

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