CurtPalme.com Home Theater Forum

Meemil · Joined: 25 Mar 2016 Posts: 96 Location: Finland

Hi there!

I recently purchased a blue tube on ebay for my Sony 1251. Tube seems good overall but theres this weird black line on the phosphor surface? What could cause this and is there anything I can do for it? Also would this affect the picture anway?

http://imgur.com/a/uqezX

Thanks, Eemil

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Anything you see on the phosphor surface will be seen on the screen. That black line is probably a scan line burn or deflection burn.

The good news is, flaws in a blue tube are least noticeable. Green tube flaws can not be missed, red flaws are pretty easy to spot, and you can get away with a lot more in the way of blue flaws before it really interferes with viewing.

Meemil · Joined: 25 Mar 2016 Posts: 96 Location: Finland

Thanks for the quick reply! And alright, I was a bit afraid of that. I still hope replacing the old tube with the new will be an improvement. Here's old vs new comparison: http://imgur.com/a/81zy2

Cheers, Eemil

Meemil · Joined: 25 Mar 2016 Posts: 96 Location: Finland

Damn seems like this ain't going to be easy on me. Just replaced the tube, everything went smoothly except when i power it on. Tube starts flickering very fast (kinda like shrinking and expanding) and making this clicking noise. I've rechecked all the connections but can't find any problems really.

As a side note, the tube is 07msp, not 07mp my PJ takes but afaik they're interchangeable.

Cheers,
Eemil

thelasernut · Joined: 10 Jan 2007 Posts: 24 Location: London UK

I had a similar fault in a 4inch tube in my Rank Cintel Medium Screen projector - I managed to destroy a green CRT when a decoupling capacitor went S/C so I changed the tube for the spare - only to find it was faulty and gave rapidly expanding pictures.

Close examination of the tube face revealed a lne running all the way around the phosphor where it had somehow become separated from the internal matalising so what was happening was that the EHT was jumping the gap to charge up the phosphor to give normal picture but as the phosphor discharged effectively reducing the EHT the picture expanded until the difference was enought to cause another flashover to recharge the phosphor again.

No idea how this happened but the tube was completely unusable and so had been changed for the good spare before I aquired the projector and had been put back in the new tubes box - another example of Sod's Law,

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

That's the strangest CRT fault I ever heard of.