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Norwood LCD monitor problem

I have a Norwood 17" LCD monitor. Lately it's been having this problem:

When it has been turned off for a length of time when I turn it on the it doesn't come on and the indicator LCD flickers somewhat randomly. If I unplug the VGA video cable sometimes it seems to help and stops flickering in which case another press turns it on solid yellow and reconnecting the cable turns the monitor on. Or sometimes another push will turn the monitor on and it gives the no signal indication and it will be ok when the video cable is reconnected.

However sometimes nothing works and I have to wait a few minutes for it to stop flickering. During the flickering period the screen remains off and no amount of pushing or pushing and holding any buttons help. When the monitor does come on it's perfectl normal and there's no flicker or any apparent issues with the cold cathode bulb. (But that doesn't mean there couldn't be some issue with trying to start it.) Thus far it always eventually comes on.

I tried running the monitor off a different 12 VDC source but that made no difference. This is a cheap monitor and it's not the end of the world but since it works perfectly when it does come on it seems a shame to have to junk it. I guess I can open it and see if there's anything obvious (doubtful) or if there are any capacitors back there that could be showing premature aging from heat vs. lowest quality grade and replace them on speculation.

Any ideas?

Reply to
Steve Kraus
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Hi!

Well, it sounds like a no-name monitor to me. That may or may not be a bad thing.

After reading your description of the behavior, I think it's quite possible that the power supply is faulty. Disconnecting the computer signal cable would cause the monitor to power on only enough circuitry to display an LED, typically an amber colored one. The backlight and panel usually remain off. (Some monitors do display a "check signal cable" message, however.)

Now, startup is of course the hardest time for any supply, and one that's marginal could be shutting down and repetitively starting over. If you reduce the startup load, though, the supply might make it up and stay running...at least for a while.

I would definitely advise you to look long and hard at the capacitors in the power supply. They could be cheap, bad or even both. You should also look at the backlight inverter board.

If by some chance it has an external power adapter, replacement with another that is known to output the correct voltage and needed current could solve the problem.

William

Reply to
William R. Walsh

Unfortunately I already tried using an alternate supply to substitute for the brick and no dice. It does seem like maybe there's some problem getting the bulb started although I don't see any flashings nor issues once it's on. I guess my next step is to open it up and if see if I can disconnect the bulb if that makes the rest of the electronics start normally. Then look for any tired caps in the monitor itself.

Yes, it's just a cheapo that I actually bought intending it for another use but when I substituted it at home for a CRT "just for testing" even though the CRT was a nice one I was immediately hooked and there was no going back. LOL

William R. Walsh wrote:

Reply to
Steve Kraus

Hi!

I didn't really think this would bring any improvement. It never hurts to try and now you have confirmed that the trouble is in the monitor.

That's symptomatic of a faulty backlight inverter. Startup is the hardest time for it.

Be careful! The inverter and its supporting electronics may assume that the bulb is always present and may not take kindly to operating without the bulb attached. Something could blow up.

I would not be surprised if you found some.

I've been down that road, although I only have three flat panels right now. One is a Gateway that while nice in its day (2000), does not really compare to the panels of today very well. I also have an Acer X163W that is the *strangest* panel I've ever seen--it's a 15" 16:9 panel. Still it works well and fits in places where other panels won't. It's just that the resolution of the panel is a bit strange.

By far and away the best flat panel I have is a 15" Samsung Syncmaster. It was an eBay find that had been very gently used before its owner passed away. Even though it is small, I find myself using the computer attached to it more often than I do my fancy computer with the 19" ViewSonic CRT!

William

Reply to
William R. Walsh

I'm seeing bad caps on the inverter boards lately. Look around the final transformer for the bulbs there are some electrolytics on the input side and high voltage on the output side. Some of the better control/feedback chips will shutdown of the load isn't right.

Reply to
George Jetson

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