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Thread: Tube swap on CM8833 MK2 question.

  1. #1
    drojman's Avatar
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    Default Tube swap on CM8833 MK2 question.

    Hi folks,

    I have two of the aforementioned monitors. One has a new flyback and new power switch, as well as some other new bits, but a damaged screen, there seems to be some phosphor damage, and one or two not insignificant scratches. The other is in poor condition, but is barely used (apparently) and the tube is in good condition. Speakers are broken, case is in bad shape etc as well as having flyback failure, HOT failure etc. So I was considering swapping the tube from one to the other. My question is, is it better to keep the yoke and tube together, along with all the other electronics, so swap out the main board/neckboard too, or would it be simpler and perhaps better to swap soley the tubes, and keep all the electronics in the monitors the same?

    I appreciate this might seem like a lot of effort, but well with everything going on, I need something to do!

    Cheers.
    Last edited by drojman; 27th March 2020 at 01:59.

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    KBQ's Avatar
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    I'd swap the tube and the yoke together, if you've never taken a yoke off before.

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    drojman's Avatar
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    Quote Originally Posted by KBQ View Post
    I'd swap the tube and the yoke together, if you've never taken a yoke off before.
    Yoke ended up not being a problem, and overall everything seems to have been a success. No explosions at least.

    Only thing I'm struggling with is setting the voltage on the flyback using the pot. With the brightness set in the middle, black is perfect black. But I have to boost the brightness a little in real world use which gives me more greyish blacks.

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    KBQ's Avatar
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    Contrast issue. I don't have a service manual to hand but are there any pre-contrast or pre-brightness trimmers on the board?

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    drojman's Avatar
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    Quote Originally Posted by KBQ View Post
    Contrast issue. I don't have a service manual to hand but are there any pre-contrast or pre-brightness trimmers on the board?
    Yep, I have RGB pots on the neck board, and drive controls on the main board.

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