Member Avatar for pbarney

Hello everyone... this is my first post on daniweb. Hard to believe I've never signed up here before.

Here's my problem: when I turn my CRT monitor on, it looks fine for a few seconds, but then the screen goes fuzzy. It starts from the bottom, and climbs up to the top over a ~3 second period. This occurs even if the monitor is not connected to the computer when I power it on... i.e., the on screen menu looks fuzzy as well.

The good news is that it instantly clears itself up after a minute or two... occasionally, it will go fuzzy again after a few hours time, but generally returns to normal.

So what's the problem? Is this simply a sign that my monitor is on the verge of death, or is there something I can do to save it?

FYI, this is a Compaq MV940 19" CRT. Thanks for any help.

Peter

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  • Latest Post Latest Post by sittas87

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Good troubleshooting so far. The original poster has already shown the fault follows the monitor (occurs with no PC attached and with a different card), and correctly recommended isolating the video card early on. That already rules the GPU out and makes an internal-monitor cause the likeliest avenue.

The symptom — a clean image for a few seconds, then a fuzzy band that rises from bottom to top over a few seconds and only clears after the unit warms up — is characteristic of the vertical‑sweep circuitry or its supply not reaching stable operating values on power‑up. Components whose behavior changes with temperature (aged electrolytic filter caps, marginal solder joints, or vertical driver parts) commonly produce exactly this warm‑up progression.

Practical, low‑risk checks: with the monitor unplugged and after it has discharged, inspect the boards for bulged or leaking electrolytic capacitors, dark/burnt spots, cracked solder joints near the large ICs and coils, and any loose connectors. Listen for unusual noises at power‑on or smell for burning. Do not attempt internal live measurements or remove the anode cap unless fully trained — CRTs retain lethal voltages even when unplugged.

Reasonable repair steps that technicians use: replace old electrolytic filter caps on the power and vertical boards with low‑ESR, high‑temperature (105 °C) equivalents and reflow suspect solder joints; these fixes are inexpensive and often cure warm‑up faults. If the vertical output stage or the monitor’s high‑voltage assembly is failing, repair becomes more complex and less cost‑effective; in that case replacement or professional service is the pragmatic choice.

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Member Avatar for sittas87

reading your post and realising that great minds think alike[monitor is running towards end of days].Most likely the case.Ive never heard of a Graphics card thats causing your monitor to behave like this but than again it doesnt mean that its impossible. you can try a graphics card just for testing if indeed its the monitor. Before buying a new monitor do run that test first
??

Member Avatar for pbarney

I've confirmed the problem still exists with another graphics card. In fact, I've confirmed that the problem exists even without a graphics card... i.e., the monitor simply being powered on with no connection.

I'm wondering if anyone here knows anything about monitors... for example, do I need a new flyback transformer? A new capacitor somewhere?

I can replace the monitor easily enough, but I'm a tinkerer, and I'd like to figure out the problem and attempt to fix it. (yes, I'm aware of the dangers of working inside of a monitor.)

Member Avatar for sittas87

ohk personally I never work on monitors cause of the dangers as you know. youll find someone here that will be willing to give you that creepy info.not my style i wanna live thats why I just buy a new one on companies expense
So I believe you swopped the monitors to see if the prob is indeed the monitor

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