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I'm having an ongoing problem with my Samsung 955df monitor. When the monitor has been off, in standby or on screen saver for awhile and I start it up the picture is great. Within minutes it slowly starts to degrade (goes out of focus)until it's barely readable. This monitor has 2 focus controls (edge and middle) and I've tried adjusting both after it is warmed up (1 hour or so), to no avail. I can get 1 area focused, at the expense of the others (left, middle or right). I've tried different refresh rates and resolutions with no results. I'm wondering if overheating may be causing this...the unit has never been opened and the environment here is pretty dusty (I regularly blow out my tower with dry aerosol). Or am I drawing at straws with that idea?

ASUS A7M266 MB,
AMD Athlon XP2100+ CPU,
PNY Verto GeForce4 ti4600 graphics,
1gb Crucial RAM

Thanks.

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  • Latest Post Latest Post by TallCool1

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Follow-up for — building on ’s observation, here are practical isolation steps, safety notes, and repair options that weren’t covered yet.

Quick isolation checklist (do these before paying for anything):

  • Try the monitor with a different computer or laptop using a known-good VGA cable; then try your computer with a different monitor. That tells you whether the fault follows the PC, the cable, or the display.
  • Swap the analog cable and inspect connector pins and the ferrite/grounding on the cable. A marginal contact can change with temperature.
  • Move nearby magnetic or powered objects (speakers, phones, power bricks) well away and run the monitor’s degauss cycle to rule out stray magnetic interference.
  • Capture the failure pattern: take time-stamped photos every few minutes while the screen degrades and note ambient temperature. Those images and times are very helpful to a tech.

Cleaning, ventilation and safety:

  • Unplug and blow out external vents with a can of compressed air (keep the can upright, short bursts). Do not power or open the case yourself unless you are trained — CRTs and their associated boards can retain lethal charge. External dust can raise internal temps and accelerate failures, so keep vents clear and allow good airflow.

Repair vs replace:

  • If your tests show the problem stays with the monitor, get an itemized repair quote from a reputable electronics shop. Ask them to check the focus/deflection driver boards, power-supply capacitors and solder joints rather than committing to a full-module swap. Compare the quote to the price of a used working replacement or a modern flat-panel — for older CRTs repair can sometimes cost more than replacement.

When you contact service, give the model (Samsung 955df), a concise symptom timeline (minutes-to-degrade), your isolation results, and the photos — that speeds diagnosis and avoids unnecessary work.

Member Avatar for TallCool1

I'm having an ongoing problem with my Samsung 955df monitor. When the monitor has been off, in standby or on screen saver for awhile and I start it up the picture is great.

Not good news, I'm afraid. You have a bad flyback (a/k/a integrated high-voltage transformer -- it runs hot) or a problem with the dynamic-focus circuitry. The focus voltages are derived from a resistor network integrated into the IHVT, then modulated for edge focus. If one of the plated connections becomes thermally intermittent, the voltages (hence focus) will drift.

The IHVT is the second-most expensive component in a monitor.

The monitor might still be under warranty.

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