In article <3ko157$qnc@sand.cis.ufl.edu> Andrew Miller writes: > I've seen several posts about monitors changing color, generally from > white to yellow. I have a similar problem, my colors change for a > second or two, then switch back. It started a couple of weeks ago, > I thought i saw something flicker, but it was so fast i dismissed it. > Then as i paid more attention i would notice that white turned to a > light blue for a while then switched back. This wasn't just in windows > it was in every mode, even dos. Anyhow it just got worse and worse, > sometimes the screen would go very pink. Sometimes i would lose > green entirely. I checked the cables but they were firmly attached > (with those screw things on the connectors). I got so fed up with it > i sent it back to MAG, i'm using a generic USIT vga monitor (only > capable of 640x480 at @60hz while i'm waiting for a replacement. I'm > going through sheer hell putting up with this screen while i wait but > it's better than nothing. > Can anyone give me anyclue to what's going on? I don't think it's my > video card (ATI mach64 2mb VRAM), cause it works fine with this > monitor. I don't think it happened when i first got the monitor. > Andy Miller > rhuk@cis.ufl.edu I guess you were not paying attention until you had a problem, huh? Monitor Manufacturing Quality and Cold Solder Joints: ---------------------------------------------------- Any intermittent problems with monitors that cuase random sudden changes in the picture brightness, color, size, or position are often a result of bad connections. Bad solder joints are very common in monitors due both to poor quality manufacturing as well as to deterioration of the solder bond after numerous thermal cycles and components running at high temperature. Without knowing anything about the circuitry, it is usually possible to cure these problems by locating all bad solder connections and cleaning and reseating internal connectors. The term 'cold solder joint' strictly refers to a solder connection that was either not heated enough during manufacturing, was cooled too quickly, or where part pins were moved before the solder had a chance to solidify. A similar situation can develop over time with thermal cycling where parts are not properly fastened and are essentially being held in by the solder alone. Both situations are most common with the pins of large components like transformers, power transistors and power resistors, and large connectors. The pins of the components have a large thermal mass and may not get hot enough during manufacturing. Also, they are relatively massive and may flex the connection due to vibration or thermal expansiona and contraction. These problems are particularly common with TVs and monitors - especially cheaper monitors. To locate cold solder joints, use a strong light and magnifier and examine the pins of large components for hairline cracks in the solder around the pin. Gently wiggle the component if possible (with the power off). Any detectable movement at the joint indicates a problem. With the power on, gently prod the circuit board and suspect components with an insulated tool to see if the problem can be effected. When in doubt, resolder any suspicious connections. Some monitors may use double sided circuit boards which do not have plated through holes. In these cases, solder both top and bottom to be sure that the connections are solid. Use a large enough soldering iron to assure that your solder connection is solid. Put a bit of new solder with flux on every connection you touch up even if there was plenty of solder there before. Intermittent or Missing Colors: ------------------------------ This is a catchall for some of the most common monitor problems. Most of the causes boil down to bad connections of one form or another. 1. VGA or other video input cable. Sometimes these develop intermittent problems at the connector to the VGA board. These may be internal to the cable in which case it will need to be replaced or if you are handy and have infinite patience, you can replace just the VGA connector. Alternatively, the male pins of the cable may not be making good contact with the female VGA socket. First try contact cleaner. If this does not work, gently squishing the male pins with a pair of needlenose pliers may provide temporary or permenant relief if the pins are a tad too small. However, if you go too far, you can damage or break the pins or cause the female sockets to become enlarged and loose fitting for any other monitor you may use. There may be cold solder joints on the VGA board itself at the VGA connector. These can be resoldered. 2. Printed circuit board on the CRT neck. This is a common location for cold solder joints. Check with a bright light and magnifying glass for hairline cracks around the pins of larger parts. Prod and tap with an insulated tool to see if the problem is effected. Resolder if necessary. 3. Cold solder joints elsewhere in monitor usually around the pins of large parts such as transformers, power transistors and resistors, and internal connectors. 4. Internal connectors that need to be cleaned and reseated. Remove, clean with contact cleaner, burnish, and replace. --- sam .