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Macintosh Portrait Display -- low brightness and out of focus?

tattar8

Well-known member
I've recently gotten my hands on one of these. Hooked it up to my Q950 and it displayed an image without any problems. But the image isn't very bright, and at "full" brightness it's also somewhat blurry; a far cry from the "crystal-clear text" reputation this beast has. Would this be a problem that can be addressed by recapping it, or is this a case where the CRT itself is going bad?
 

beachycove

Well-known member
Obviously, we’ve got to assume that any 1990-ish monitor needs recapped at this point. So I’d say that if there is no burn-in, it is worth the small expense and the not-so-small effort required to attempt a speculative repair. Given no burn-in, my working assumption would be that the thing hadn’t been used endlessly and so still had service left in it.

Having said which, what I’ve recently seen with a colour monitor of similar vintage is clarity and brightness to start with, fading away into virtual illegibility after a couple of hours. But there have to be so many variables in all that potential for leaking, creeping capacitor goo that drawing comparisons has to be pointless — plus, the technology is different anyway.

What I can tell you is that a portrait monitor genuinely is crystal clear when working and so is wonderful for text work. I much prefer a proper b/w or greyscale to a colour crt for certain tasks.
 

tattar8

Well-known member
Does it get any better if you leave it on for a bit?
I left it on for like 30 minutes and there was no change.

If I reduce the brightness to about half (which since it's not very bright to begin with becomes rather dim), it becomes much less blurry.

There's a very faint burn-in of the menu bar, so it was probably used for some time but probably not so much that the CRT is gone. I guess I'll recap it, I saw a post on here with a complete list of caps needed.
 

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Johnnya101

Well-known member
Don't those flybacks have a focus adjustment on them of some sort?

Also, we can guess the amount of hours to know if the tube is gone by opening it up and posting a photo of the flyback. It will be pretty obvious if it is high hours or not. Pretty sure you REALLY have to have one of these on for months/years on end to even get it to dim/lose focus. The only ones I have heard of dimming from use were used in schools. I would think you would see some major burn in as well, a menu bar counts as normal use to me.
 

tattar8

Well-known member
I messed with the control pots, got it a bit brighter by cranking up the gain control. It looks like the overall focus is fine, it's just the vertical focus that's bad. I tried messing with the VF pot, which does help but it's still blurry even at its max setting. The image is also noisy at the top and bottom of the screen, so I'm thinking that I can't really do anything more before recapping it.
 

Johnnya101

Well-known member
Yeah, definitely recap first and see what happens. When it's apart, get a photo of the flyback so we can estimate hours.
 

tattar8

Well-known member
So after a year and a half I've finally gotten around to this. I took the machine apart, replaced all the caps, and am in the process of reassembling it. The problem is that some of the internal connectors have ambiguous polarity, and like an idiot I forgot to take any photos before unplugging them. The service manual fails to provide any information. Does anyone have photos of the inside of it that I can use for comparison?
 
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