My PC monitor often turns off/blacks out for a second when the fridge starts up. It is on the same circuit as the fridge, so I assume this is due to the sudden draw from the fridge causing noise or a drop in the AC circuit.

No other appliances are noticeably affected, and I have no reason to suspect bad wiring in the apartment.

I'm wondering if the power supply board in the monitor is wearing out, and it can't deal with the (normal?) noise in the AC caused by the fridge start up.

I disassembled the monitor to inspect the power board but found no signs of damage or failure - capacitors are fine, no damaged traces etc.

Is this a problem with the monitor? Is it worth replacing the power board anyway? Would using a surge protector help at all?


Replies (as I can't comment):

@DarthCaniac: it's a standard single-door fridge-freezer, plugged into a dedicated socket on a normal UK ring main. UK ring mains are typically rated for 30A total, with normal household sockets rated for 13A each. There are no other high-power appliances running on the sockets ring main. I can't move the fridge or monitor to a different circuit, because there is only one ring main for the sockets (lights, cooker, boiler etc. are of course on their own circuits, though).

@longneck: Flat panel LED monitor. The fridge and wiring are no older than about 6 years - the apartment is a new build, and I have no reason to suspect bad wiring.

  • 1
    How large is the fridge? How many amps is the circuit rated at, and what other devices on the circuit are running when the problem occurs? Have you considered moving the monitor to another circuit? Jun 10, 2015 at 14:46
  • 1
    Tube monitor, or flat panel? How old is it? How old is the fridge? How old is the wiring in your home?
    – longneck
    Jun 10, 2015 at 15:14
  • Possible duplicate: diy.stackexchange.com/questions/28002/…
    – maplemale
    Jun 10, 2015 at 17:50

1 Answer 1


Pretty clearly the sudden draw from starting the fridge's compressor is pulling down the line enough to cause the monitor to hiccup. The question is what to do about it. Some suggestions:

  1. Buy a new monitor (they're getting cheaper all the time)
  2. Get a line voltage stabilizer (e.g. APC's Line-R 300VA, although that one is 120VAC)
  3. Admire the fact that you have a very nice "Refrigerator Just Turned On" sensing system
  • A good UPS can also serve as a voltage stabilizer. (Found that out in a hotel whose ancient wiring delivered 90VAC on a good day, and dropped further when someone was using the copier in the business center... the DAT deck reset itself continuously until we plugged it into the UPS.)
    – keshlam
    Jul 16, 2015 at 14:18
  • Good suggestion. You probably want a line-interactive unit; see en.wikipedia.org/wiki/… Jul 16, 2015 at 15:56

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