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Thread: MAcintosh Classic CRT Inside Apple IIc monitor

  1. #1
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    Default MAcintosh Classic CRT Inside Apple IIc monitor

    The Macintosh CRT is a 9" B&W tube I think we are all familiar with. I have spares and not much to do with them. They are the same dimensions as a 9" green screen CRT from an Apple IIc monitor. Can I swap in a black and white CRT to replace a blown green CRT? Im talking a yoke swap OR putting new ends on the MAC yoke for the vert. and horiz. Has anyone done this?

  2. #2

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    I know I've seen a couple examples of those old Macs with a green CRTs over the years, and I've heard that the IIc tube fits just fine(though I think maybe one said they were using a Compaq portable CRT), so I'd guess that there's at least a chance it'll work the other way. It's been years since I've seen an old Mac up close and I saw a YouTube video recently of a IIc monitor, and the deflection yoke seemed familiar to what I'd worked with in the past. I would probably try the new tube with existing yoke in the monitor, but I'm also saying that not having either on hand. I think it'll definitely be doable, but you may just have some trial and error ahead of you and I'd recommend the least resistive paths first.

  3. #3

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    Quote Originally Posted by VERAULT View Post
    The Macintosh CRT is a 9" B&W tube I think we are all familiar with. I have spares and not much to do with them. They are the same dimensions as a 9" green screen CRT from an Apple IIc monitor. Can I swap in a black and white CRT to replace a blown green CRT? Im talking a yoke swap OR putting new ends on the MAC yoke for the vert. and horiz. Has anyone done this?
    If the CRT's you propose to swap have essentially the same part number, but say P31 for green and P4 white, or their part numbers indicate they are simply the same tube with a different phosphor, depending on the phosphor coding system, the swap is easy. You do not need to swap the yokes for a monochrome CRT swap (It is often easier in a color set to swap the CRT & yoke together because of the multiple adjustments required).

    If the CRT's are differently numbered a range of things needs checking for a match:

    1) Physical geometry, face curvature, length, deflection angle, neck diameter
    2) heater voltage
    3) guns structure, number of elements and typical focus voltage.
    4) pin array at the base.

    I have successfully replaced number of CRT's with different part number and different gun connections and phosphors and it usually works if you pay attention to the gun wiring and the heater voltage is correct.

    If the two tubes are identical, just aside from the phosphor, it makes life very easy. I have never been too fond of green phosphor, probably because it has a fairly unimpressive grey scale on a picture, my favorites are white & Amber. I fitted a white CRT to an Apple II monitor in place of the green CRT it originally had.

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    Quote Originally Posted by confusedyeti View Post
    I know I've seen a couple examples of those old Macs with a green CRTs over the years, and I've heard that the IIc tube fits just fine(though I think maybe one said they were using a Compaq portable CRT), so I'd guess that there's at least a chance it'll work the other way. It's been years since I've seen an old Mac up close and I saw a YouTube video recently of a IIc monitor, and the deflection yoke seemed familiar to what I'd worked with in the past. I would probably try the new tube with existing yoke in the monitor, but I'm also saying that not having either on hand. I think it'll definitely be doable, but you may just have some trial and error ahead of you and I'd recommend the least resistive paths first.
    Problem is I have a IIc tube with a broken Yoke so that was what inspired the question.

    Hugo, I would definitely check everything out first. Just curious which B&W tube did you end up putting in the Monitor II? (if it works in the monitor II it will work in the Monitor III)

  5. #5

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    I didn't document it, but it would have been one of two CRT's. Looking at the Apple IIc schematic, the CRT there is a C10M42P31, and I must have found an equivalent as I wrote beside that 10ATY31N, so I must have put either a C10M42P4 or a 10ATY4N, which are the white versions of these CRT's. It looks like the 10ATY4N was used in Apple macs.

    I just did a quick look and they have the 10ATY4N at CRT solutions (they also have a lot of CRT equivalence manuals) so it might be worth double checking before you buy that they also think this is electrically compatible with the C10M42P31 tube. I normally wouldn't write an alternate CRT number on a schematic that wouldn't work as a substitute, but it would just pay to double check.

    https://crt-solutions.myshopify.com/products/10aty4n

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    There seems to be a number of 9" monochrome tubes that were REALLY commonplace for a number of decades. For the most part the pin designations and filament voltages were the same but nobody has ever really compiled a compatibility matrix to verify much less found the datasheets for the jugs Apple used.
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    Well I have a ton of machines. I had a IIC monitor with a bad yoke (but perfect tube), Recently got a new IIc monitor yoke (and the tube was included to my surprise) So I am thinking of swapping a mac classic b&w tube for the IIc green CRT and vice versa just to be different. I think an old MAC in Green is interesting, and a small 9" white phosphor Apple II is also interesting.

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    Quote Originally Posted by NeXT View Post
    There seems to be a number of 9" monochrome tubes that were REALLY commonplace for a number of decades. For the most part the pin designations and filament voltages were the same but nobody has ever really compiled a compatibility matrix to verify much less found the datasheets for the jugs Apple used.
    The major CRT suppliers do have equivalence listings. They won't scan or post these on the net. But say if you contact CRT solutions or NewTubes on ebay and ask if they have an equivalent CRT to a type number you give them they will tell you. It is surprising how many equivalent types they have, sometimes with only very small differences or about the same. For example, they keep an equivalent color CRT for the IBM5153, the only practical difference is that it has a lighter rather than a darker grey faceplate, but you would never find the data sheets on the net to have figured this out for yourself....the moral of the story is that everything is not on the net...yet.

    Edit: I noticed there was a 10ATY4N on ebay for $39 recently.
    Last edited by Hugo Holden; March 7th, 2021 at 01:27 PM.

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    I have noticed a large abundance of MAC 9" tubes on eBay lately to be honest. Seems someone wants to make some money off all the dead Classic and Classic 2's out there.

  10. #10
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    Quote Originally Posted by VERAULT View Post
    I have noticed a large abundance of MAC 9" tubes on eBay lately to be honest. Seems someone wants to make some money off all the dead Classic and Classic 2's out there.
    I have seen quite a few swaps into a Mac as most 9" MDA compatible tubes fit nicely into it. You can easily put a green 9" from a Kaypro or amber 9" from a Compaq portably into classic Macs.

    EXm3XUHX0AIsHbN.jpeg

    I have never seen the opposite attempted. Please keep us posted!

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