Red Tint on Screen

chrisjs100

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Hi all, What would cause a red tint to cover the screen and if you hit the side of the cabinet it will clear up. Over time the red tint does come back. Any ideas on problem and how to fix it?
 
Does the red tint have strange diaganol lines across it? It's likely either your tube has an intermittant short in it, or you have a transistor or pot going bad on the neckboard. If you have the lines, I'd lean more towards a short in the tube, if you have no lines, I'd lean more towards the pot.
 
If there's no lines, it's probably not the tube. So it's likely something on the neckboard of the monitor, try just twisting the red adjustment pots on the neckboard back and forth a couple of times, sometimes they get in a weird spot where they intermittantly make contact. Look close too and make sure the three transistors on the neckboard aren't touching each other, sometimes that will make the colors lock on.

As far as cost, they don't make new monitors anymore so it would be much, much, much cheaper to fix it.
 
if you have the proper tools to do so, I would desolder all 3 color drive transistors, scrape off all the flux residue, and then reinstall them all, making sure you bend all the legs back straight again.

I generally do this with ANY monitor that I re-cap, and started doing so when I was re-capping all my Nintendo monitors and found missing primary colors when I was done. my best guess is that when you install fresh capacitors in, it drives everything harder again and will result in shoddy contact from the color drive transistors. I've never noticed this on any other type of monitor besides the Sanyos I've done, but I do it anyway as a means of preventative maintenance.

additionally, cause they can get so hot, they can become prone to cold solder as well. other instances on newer monitors, the transistors get so hot that the solder pads/traces will lift. I correct these either with jumper wires (if the traces are damaged) or I will bend the transistor legs at 90 degree angles to kind of "hook" the solder pads better and prevent them from moving anymore. if you do this though, be careful that you don't touch the transistor legs to other adjacent traces or you can short something out. (might have to cut the tips)

last place to check would be the video signal header, the connector that goes from the JAMMA harness to the monitor's input. on K7000s and some other chassis these are also commonly affected by cold solder.

you can either use a solder sucker to remove the old solder and apply new solder, or you can just add more solder and re-melt the solder joints. whatever works.
 
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