pretty new CRT (in hours) - goes GREEN with lines

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    • pretty new CRT (in hours) - goes GREEN with lines

      Hi Folks,

      I bought some NOS 22" CRT's that were made in China I believe about 2006 or 2007. It's a 22" flatscreen and I have it in a cocktail cabinet. It's been on for about a year, and what occasionally happens is that the screen goes very brightly green with some lines present - and you can barely see the actual image "underneath" the green color.

      Usually turning the system off and back on works to clear it - but more recently I have had to leave it off for a couple of hours before turning it back and things are back to "normal".

      I am pretty sure this is the electronics of the CRT - but wanted to throw it by the smart folk here before I pull the cabinet apart and put in a new board.

      Thanks,

      Matt
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      Arcade MultiSystems:

      Sega: ST-V (Darksoft), Naomi 2 w/Net Dimm,Capcom CPS2 (Darksoft) , Capcom CPS3 (Darksoft), Neo Geo MVS 4-Slot (Darksoft *soon*)
    • It can be a short between 2 electrodes inside the picture tube.
      Specially on horizontally mounted picture tubes (like in your case) contamination all collects into the neck of the tube where the electrodes are close together. Normally, if the problem persists, desoldering the (in your case) green color drive transistor is the test procedure to figure out if it's the tube or the electronics at fault. If you have a spare monitor chassis, you can test with that and see if the problem is still there.

      Since the fault only appears intermittend, it's a bit more difficult to do the drive transistor removal test. (Unless you know for sure the problem will show up after an amount of time.)

      Another test you could try is exchanging the drive transistor of 2 colors. If the transistor is bad, the screen should become all red or blue after the swap. In such case you need to switch the drive transistor.
    • Thanks for the comments - I do have a spare board as well as tube... I think I will swap out the electronics board first to see if that resolves the issue, and then go from there to find the fault.

      Matt
      Arcade MultiSystems:

      Sega: ST-V (Darksoft), Naomi 2 w/Net Dimm,Capcom CPS2 (Darksoft) , Capcom CPS3 (Darksoft), Neo Geo MVS 4-Slot (Darksoft *soon*)
    • mathewbeall wrote:

      Thanks for the comments - I do have a spare board as well as tube... I think I will swap out the electronics board first to see if that resolves the issue, and then go from there to find the fault.

      Matt
      Having a spare chassis is the best solution to test if its the tube or the chassis. It does narrow down if you have a shorted G1 or if its something board lvl, like a drive transistor.
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