Compact Mac Screen Size

[Tempest]

Quick question for everyone.  Is there any harm in adjusting the horizontal and vertical size of the picture in a compact Mac so it fills the entire screen (no black border)? I currently have my Mac Classic adjusted that way and haven't had any issues, but I don't want to damage it. I thought I read done where that while it does put a little more stress on the monitor, it was ok to do.  The only side effect being a loss of sharpness (I've never noticed this myself).

The whole reason this came up is that I turned my Classic on after not being used for a few months and saw that the picture had two 'interference lines' going across the screen (one towards the top and one towards the bottom). This freaked me out and I immediately thought that it could be due to my adjusting (although I did that years ago and have had no issues). However I gave the Mac a swift whack on the side of the case and it immediately went away and hasn't come back. It was weird, but it made me think a bit.

 

[Paralel]

As long as your A/B can handle it, its no problem

A whack worked? Sounds like either a lose or dying component.

 

[Elfen]

For one thing, you lose WYSIWYG printing by adjusting the screen out of its size. Comparing printing from an ImageWriter II or LaserPrinter - the size of the image you have on the screen is the exact size on the printed page.

Another issue is having it outside of its size range, you are shifted the frequencies that keep the screen in place by a tiny amount and parts will wear out faster. The truth in this is - lets say if a part of said to last 104 weeks (2 years) when properly tuned, then out of tune, it will last 100 weeks (or about 1 year 10+ months). That might not seem like like much of a difference.

For me the first is more important than the second. In doing graphic work, because the screen is not squared, if I draw a circle on the screen but it gets printed as an oval or an egg shape, it's going to drive me crazy. And until I figure out the problem is with the screen and not the printer, I will never solve the issue.

 

[Tempest]

I'm only playing games, so WYSIWYG isn't important to me.

Yeah I was as surprised as you are about the whack thing (it was more out of frustration than trying to fix it).  The board was recapped not too long ago so I can't believe that anything is dying.  Maybe something is loose (I did move the system around a bit), but I'm not sure what it would be to cause those two interference lines.

 

[MidnightCommando]

I'd suggest freshening up a few solder joints on the analogue board if a simple thud was enough to fix the issue. 

Intermittent contact might appear like this, in which case it could just be cracking of the solder joints. 

Don't use lead-free solder, it's more brittle and will cause problems down the track. 

 

[Elfen]

MidnightComando is right - loose/breaking solder joints. You need to desolder and resolder the joints on the Analog Board.

One set of joints to look at is where the harness goes to the logic board. Another set of joints is at the Yoke connector. Then look at the usual suspects (C1, Q1, D1 L1 and T1 - all along the top of the analog board). You need to look at the solder joints and desolder and resolder with fresh solder and flux anything that looks crusty.

DO NOT Heat up & Reflow Cracked Solder joints. They will break again after a few weeks time. Desoldering, cleaning up the board and resoldering with fresh solder and flux will give a repaired connection that will last for years.

 

[Bunsen]

The black borders on compact Mac CRTs are left there so that you are not driving your analog board components at too high a voltage [1].  It's not recommended to over-volt those components: some boards will handle them just fine, some will suffer increased wear, and it's pure pot luck how your board will respond, especially given how old they all are now.

[1] not frequency - the frequencies remain exactly the same

 

[Tempest]

Well my board seems to be able to handle it ok, or I think it would have died by now.  I suppose if it does die I can always pick up a new one as Mac Classics are the one classic Mac no one seems to want (they're seriously misunderstood creatures).  I'm also loathe to go back in there an fiddle with the adjusts again.

I suppose there could be a solder joint going bad on the analog board.  If so, repairing it is well beyond my capabilities.  I can solder simple things (wires and what not) but this is an advanced job.  Maybe I can talk someone into it at VCF Midwest this year?

 

[Scott Baret]

You can always send the AB to Uniserver. He did a great job with my Classic II's board.

As for the dimensions...if you have Larry Pina's Test Pattern Generator, it actually tells you how to get the proper size for WYSIWYG. It comes with one of this Mac repair books (not sure which one offhand but I snagged my copy at the VCF East for a buck two years ago). To size it, use a soft tape measurer like the ones tailors and doctors use to measure waist size and head circumference.

The "maximum size" trick is one which has been around forever, with the AB warnings to boot. If you get it completely redone, you should be OK; I have used an SE and a Plus over extended periods of time which had these mods done to them. (They came to me that way and I didn't fix them until I bought my first long T-15).

 

[SE30_Neal]

Elfen told me its 7.14 inches diagonal (from memory) on the 9 inch b&w for Wysiwig compliance although you had better check that

 

[Paralel]

Apple actually specifies it in mm, all the way down to the 1/10 of a millimeter. Its kind of insane. I doubt anyone here can adjust a screen to micrometer accuracy.

 

[Tempest]

Well if I ever get another CM I'll leave the screen size as is.  

 

[SE30_Neal]

I wanted to change mine to fill the screen but was advised not too.