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Radius 21GS Display advice needed

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I have a Radius 21” Two Page Display (21GS) here that was given me long ago by a friend, and that I (and another member) tested earlier in the week, connected to a high end Radius card in a IIsi. This is a greyscale display intended for page layout work, technical drawing, spreadsheets, and like text work. We found the focus poor. My colleague suggested that the screen is beyond repair, owing to the need to adjust for degradation and our not being able to easily find techs with those skills any more. 


I am loathe to throw the thing out, as it is pristine. It’s also not had much use.


Anyway, I tried it again today (having finally cleared my workbench, Paul!), but connected to a different machine, and found the focus rather better but still a ways off. It should be superb. The 21GS has an 82 DPI density, which is about the same as the Apple Portrait Display (80 DPI), and it seems to me that the former ought to be about as jewel-like as the latter, which is just a pleasure to work on.


CRTs do degrade over time, and my thought is that periodic focus adjustment ought to have been engineered into the thing — that if I take the plastics off, I should find an adjustment pot. Is this a safe bet or is the old gal really for the scrapper? I have the user manual but no service manual. There are user-accessible pots on the side that allow for geometry adjustment, but none for focus. 


Radius evidently did not want us poking around in the innards of these things, but what say ye? Must there be a focus pot somewhere in the internals?


See the attached from the user manual for the Radius spin on the thing:







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On 3/10/2021 at 2:46 AM, olePigeon said:

The focus rings may have come loose on the CRT neck and just need to be adjusted a bit.  They're often glued down, but things deteriorate or break over time.

Which would be around 11 on the 1 to 10 scale of danger, right?

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11 is trying to fiddle with the anode cable and flyback transformer with the CRT on (e.g. don't!.) :eek:


With proper precautions, you can adjust the rings on the neck while the CRT is turned on.  It's relatively safe. There are a lot of YouTube videos (especially for repairing/adjusting arcade CRTs) that can show you how to do it.  Just be mindful of where you stick your fingers.  Basically, you want to avoid the anode cable and where it connects to the CRT, and the other end where it connects to the flyback transformer.  That's where you'll get a full dose of the mains and (possibly) kill ya.  At the very least, your arm will hurt for a few minutes to hours and your heart will be going a mile a minute.


If you're really, really not sure, you can always turn it off, discharge it, mark the rings in their current position, adjust it one direction, turn it on and check, turn it off, discharge it, adjust some more, etc., etc.

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On 3/10/2021 at 2:06 AM, beachycove said:

Anyway, I tried it again today (having finally cleared my workbench, Paul!), but connected to a different machine, and found the focus rather better but still a ways off.

Don't forget there was also some significant ghosting when we increased the brightness. On another note, the Quadra key works perfectly on my 950 - no need to have it recut to fit the lock. 

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The ghosting (you mean around and on the black edges?) on adjustment of brightness & contrast is just as described in the manual, so I am hoping that that is not an issue.


The response here is encouraging enough that I think I may try to hold onto it until I can try to get it fixed, which means taking it along on a cross-country move, but there will be a moving truck, so all things are possible. I'll likely be able to find an old-school TV repairman where I'm going, as my cousin knows everyone and his business among the 70-odd year-olds, and in fact my next door neighbour there has a long technical background and might know the score. If that doesn't work, well, I have Youtube and advice on here to go by, though that is by far not my first preference. I'm afraid of these CRTs.


Thanks to all.

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