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Computer Monitor Turns off on Transmit

Discussion in 'Ham Radio Discussions' started by W0CD, Sep 28, 2019.

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  1. W0CD

    W0CD Premium Subscriber QRZ Page

    Hi all. I see a lot of posts about interference caused by computer monitors, but this is a little different.

    I have a 27" LCD monitor that will shut off every time I key the radio on bands 20m/15m (haven't tested above those bands). I have to unplug the monitor power supply from the outlet for a second to regain functionality. Simply unplugging the cord from the back of the monitor and re-plugging it back in doesn't do the trick.

    Radio: TS-450S
    Antenna: Rotatable Dipole in attic; roughly 25' away
    Notes: Radio room is in rental house. Radio is not grounded.

    There doesn't seem to be any interference caused by the radio on other monitors (laptops) on those bands.

    Any thoughts or solutions?

  2. KK5JY

    KK5JY Ham Member QRZ Page

    Sure, just choke the leads to the display, as close to the display as possible. Wrap two or three turns of the video and power cables on a ferrite bead or torroid. Use separate beads for each cable if that makes it easier. Fair-rite #43 is probably the best material for those particular bands.

    There's a chance that still won't fix it, but it's a very easy and very cheap experiment to try and if it fixes it, you're done. :)

    Edit: By the way, you are using a coaxial choke at the feed point of your dipole in the attic, right?
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    That is strange.

    Sounds like a bad connection in the AC outlet. Or is the power supply a external brick ?

    What model of monitor is it ?
    K2NCC likes this.
  4. K2NCC

    K2NCC Ham Member QRZ Page

    Please tell us the brand/model of the monitor. So we know which one not to buy.
  5. K2CD

    K2CD Premium Subscriber QRZ Page

    Is this a monitor with touch controls instead of actual buttons? I have three monitors in the shack. Two with actual buttons, one with touch controls (Lenovo). The one with touch controls will sometimes go nuts on 20 meters when my beam is pointed west and I am running an amplifier. It acts as though I am touching the buttons. Maybe yours is doing something similar, but locking up the processor in it. Try a different monitor. When my beam is pointed west it is over the shack, similar to you having a dipole in the attic.
    K2NCC likes this.
  6. W3WN

    W3WN Premium Subscriber QRZ Page

    Based on your description, it sounds like the monitor power supply (“brick”) may be the issue. A good many of these switching power supplies are made on the cheap, and especially if they have been on for a long time, are susceptible to overheating and component failure.

    I’ve run into this issue before with some of the Viewsonic brand monitors, and with a “Westinghouse” monitor as well (despite the name, it’s not REALLY a Westinghouse monitor, but never mind that now)

    When you turn your monitor off, you do NOT also turn off the brick. It stays powered on 24/7 until it is physically unplugged.


    (1) Wrap the brick power cord and DC feed to the monitor around a ferrite core, or equivalent.
    (2) If the monitor is more than 2 years old, buy a new brick. You can usually find them for under $25 or less each. Check with the manufacturer’s website to see what a replacement cost is, and search the usual auction sites as well.
    (3) Buy a new monitor. One without a brick!
    WA9SVD likes this.
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    What model is the display ? Is it a monitor or TV with antenna attached ?
  8. W0CD

    W0CD Premium Subscriber QRZ Page

  9. W3WN

    W3WN Premium Subscriber QRZ Page

    If that monitor is under a year old, call Dell tech support and tell them that the power supply is failing. They should replace it under warranty. (And it’s not a lie, as it should NOT be so susceptible to EMI).

    If it’s older, all them anyway. They may be willing to send you a replacement anyway.
  10. WB6CXC

    WB6CXC Ham Member QRZ Page

    If I could choose, I would go with #31 material below 30MHz. #43 is good, but #31 is a little bit better, especially at the lower end.

    I have a rig location where one end of a multiband dipole is within 20 ft of my desk. At some frequencies when I crank the power above 50W My wired mouse, keyboard, and monitor would all glitch. Multiple turns through some #31 clamp-cores did the job. Buy a lot of cores, and keep adding them until the problem goes away, Then if you are ambitious you can start removing some to see where you really need them.
    NL7W, KY5U and W0CD like this.

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