After about a decade of searching, I finally found and bought a Macintosh Colour Classic. In comparison to other Colour Classics on the market, this one was a bargain in every sense of the word, only $50 AUD. I don't specifically make a case of finding inanimate objects adorable, but this comes fairly close.
The significant reduction in the price is due to the amount of wear and tear this machine has. Two plastic tabs on the internal chassis were snapped off, the front bezel had a small stress fracture on the inside, the outside was covered in permanent marker, the Floppy Drive was seized solid, the SMT capacitors on the Logic Board are leaking and the machine was caked thick with dust on every internal surface.
Needless to say, it needed some love. It's had many repairs to the ABS plastic, a thorough cleaning of every surface and a freshly reconditioned 1.44mb Floppy Drive installed. The Keyboard and Mouse are fully reconditioned, and I've started on repairing the Logic Board as well.
The internal damage made me think the machine has been jostled around a bit in transit, which could explain the issues with its built-in 10" RGB Sony Trinitron display. The Geometry of the display seems to be off, in particular the top left corner appears to "sag" compared to the rest of the top edge of the raster image, and the edges (particularly the bottom and top, and the right, slightly) don't appear to be parallel with the bezel.
This image shows the uneven bottom edge of the raster, but also look at the left and right corners, you can clearly see a Convergence problem:
And a couple more shots showing the Convergence issues, including the notorious top left corner:
Other than this, the display is sharp, flicker free and warms up almost immediately. I don't believe the CRT is so far gone that it can't be repaired, and I wouldn't be surprised to find that it simply has poor alignment and adjustments. However it seems like an awful lot for the Geometry, Tilt and Convergence to all be out, and I can't be sure that there isn't a further underlying issue. The machine is 20 years old, so I suppose it's possible for the adjustments to be out of whack with the aged components.
There are quite a few adjustments on the Analog Board, including:
There are also several metal strips around the neck of the CRT to further tune the Convergence.
I'd copy the relevant pages from the Macintosh Color Classic service manual here, but it would take up several pages of the thread in images. If you want to have a look though, it's available in PDF form here - https://cdn.badcaps-static.com/pdfs/...199841db2b.pdf - look under the section "Adjustments" in the table of contents. It's only a couple of meg, so it may be worth taking a look at, even if just to see what adjustments I'm referring to.
I've worked on CRTs before, but only the 9" Black & White Clinton and Samsung CRTs from machines like the Macintosh 128k, 512k, Plus and SE. This Trinitron is a completely different beast entirely.
What I would like is for someone a little more knowledgeable in CRTs, particularly Trinitrons, to take a look at the pictures above and tell me what they think so I have at least a starting point to begin adjusting or troubleshooting from. If I have to, I can open up the machine and take some photos if necessary.
Cheers,
Michael
The significant reduction in the price is due to the amount of wear and tear this machine has. Two plastic tabs on the internal chassis were snapped off, the front bezel had a small stress fracture on the inside, the outside was covered in permanent marker, the Floppy Drive was seized solid, the SMT capacitors on the Logic Board are leaking and the machine was caked thick with dust on every internal surface.
Needless to say, it needed some love. It's had many repairs to the ABS plastic, a thorough cleaning of every surface and a freshly reconditioned 1.44mb Floppy Drive installed. The Keyboard and Mouse are fully reconditioned, and I've started on repairing the Logic Board as well.
The internal damage made me think the machine has been jostled around a bit in transit, which could explain the issues with its built-in 10" RGB Sony Trinitron display. The Geometry of the display seems to be off, in particular the top left corner appears to "sag" compared to the rest of the top edge of the raster image, and the edges (particularly the bottom and top, and the right, slightly) don't appear to be parallel with the bezel.
This image shows the uneven bottom edge of the raster, but also look at the left and right corners, you can clearly see a Convergence problem:
And a couple more shots showing the Convergence issues, including the notorious top left corner:
Other than this, the display is sharp, flicker free and warms up almost immediately. I don't believe the CRT is so far gone that it can't be repaired, and I wouldn't be surprised to find that it simply has poor alignment and adjustments. However it seems like an awful lot for the Geometry, Tilt and Convergence to all be out, and I can't be sure that there isn't a further underlying issue. The machine is 20 years old, so I suppose it's possible for the adjustments to be out of whack with the aged components.
There are quite a few adjustments on the Analog Board, including:
- Vertical Center
- Horizontal Center
- Vertical Size
- Horizontal Size
- Focus
- Red Background
- Green Background
- Blue Background
- Sub-Contrast
- Green Drive
- Blue Drive
- Convergence Control
- N/S Correction Control (Convergence)
- E/W Correction Control (Convergence)
- E/W Amp Control (Convergence)
- Horizontal Bow (Geometry)
- Pin Phase (Geometry)
- Vertical Angle (Geometry)
- Tilt (Physically turning the Yoke)
There are also several metal strips around the neck of the CRT to further tune the Convergence.
I'd copy the relevant pages from the Macintosh Color Classic service manual here, but it would take up several pages of the thread in images. If you want to have a look though, it's available in PDF form here - https://cdn.badcaps-static.com/pdfs/...199841db2b.pdf - look under the section "Adjustments" in the table of contents. It's only a couple of meg, so it may be worth taking a look at, even if just to see what adjustments I'm referring to.
I've worked on CRTs before, but only the 9" Black & White Clinton and Samsung CRTs from machines like the Macintosh 128k, 512k, Plus and SE. This Trinitron is a completely different beast entirely.
What I would like is for someone a little more knowledgeable in CRTs, particularly Trinitrons, to take a look at the pictures above and tell me what they think so I have at least a starting point to begin adjusting or troubleshooting from. If I have to, I can open up the machine and take some photos if necessary.
Cheers,
Michael
Still have to recap the rest of the board, but good to see it working. I managed to repair the lifted solder pad, so the repair went fairly smoothly.
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