Apple Scanner Troubleshooting Guide
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Apple's fault-finding for the Apple Scanner has three parts: the scanner's built-in self-test, the ScanTest diagnostic with Apple's printed test chart, and a symptom chart that works through cables, fuses and modules in order. The same procedures cover the 8-bit Apple OneScanner, which shares the mechanism.[1] Routine work on the lamp, belt and fuses is on the Apple Scanner General Maintenance page.
Self-test
[edit | edit source]The scanner runs its self-test when it is switched on with the Start Scan button held down, or when ScanTest or Scan8Test is run. On the 4-bit scanner it checks the lamp, the limit switch, the home position search, ROM, RAM, the CPU port, the SCSI controller, the document-image preprocessor, the DMA controller, both gate arrays and shading. On the 8-bit scanner it checks the lamp, limit switch, home position, ROM, the scanner, correction and buffer RAM, the CPU port, the SCSI controller and the CCD clock generator.[1]
The results appear only on a Macintosh that is connected to the scanner and running AppleScan, ScanTest or Scan8Test when the test runs; a failure brings up a dialog naming the part that failed. Run without a connected Macintosh, the self-test gives no result.[1]
ScanTest diagnostics
[edit | edit source]Apple's diagnostics are ScanTest 4.4 for the 4-bit scanner and Scan8Test for the 8-bit scanner. Both need the Apple Scanner Service Test Chart, which must be flat, clean and unscratched, and should be cleaned only with a dry, lint-free cloth and kept out of sunlight. Run them under Macintosh system software 6.0.5 to 6.0.7 (6.0.7 for Scan8Test), not System 7.[2]
| Test | What it checks |
|---|---|
| Self-test | Runs automatically in ScanTest (selectable in Scan8Test): ROM, RAM, lamp (no light or dim light), home position, shading, limit switch and the logic components |
| Accuracy | Scans the chart's reference points, compares the intersections with a table, then scans again and compares the two scans (Scan8Test runs the second comparison as a separate repeatability test) |
| Greyscale | Reads the 37-zone grey strip at the bottom of the chart; a deviation of ±1 grey level from the preset values fails |
| Resolution | Measures the wedge targets at the upper left and lower right of the chart and calculates the resolution |
Before running a test, check that the SCSI cable is connected and the bus terminated, that the scanner's SCSI ID is not 7 or shared with another device, that the glass is clean inside and out, and that the chart lies face down with its black strip along the rear edge of the window and its edge against the right edge of the glass. Apple warns that any of these wrong will fail the tests and give misleading results.[2]
Symptom chart
[edit | edit source]| Symptom | Actions, in order |
|---|---|
| Power lamp off; scanner dead | Check the power cord. Check that the lamp access door is shut and its latch turned fully clockwise. Check the voltage selector setting (universal models). Check the interlock switch with a meter and replace it if it does not open and close. Check fuses FU1, FU2 and FU3 on the power supply board. Check fuse 1 on the main logic board (4-bit only). Replace the main logic board, then the power supply, then the transformer |
| Optical assembly does not move | Inspect the belt for damage or debris and clean or replace it; check the belt is tight with no slack; check the gears for damage or debris |
| Optical assembly moves once, then stops | Check the limit switch for continuity and replace it if necessary |
| Macintosh will not start, or locks during SCSI transfers | 4-bit scanner: carry out the main logic board modification (below) |
| AppleScan crashes mid-scan, or the computer hangs | Use the latest AppleScan; replace the power supply board; replace the main logic board |
| Lamp will not light or is dim | Check the lamp holder connector; check the lamp's label faces down into the holder and rotate it if not; replace the lamp; check the optical unit's flexible cable for damage and continuity; replace the inverter (or the optical assembly) |
| Scan command not carried out | Check the cable from the computer; set the scanner's SCSI ID to an unused number (factory setting 2; do not use 7 or 8); check SCSI termination; check the logic board fuse (4-bit only); replace the main logic board |
| Dark or light spots on the image | Clean the glass; adjust contrast or threshold in the software; replace the lamp; replace the main logic board; replace the optical assembly |
| Scan runs but the image does not reach the computer | Check the interface connector; replace the optical assembly; check the logic board fuse; replace the main logic board |
| Wrong image on screen | Scan the test chart; clean the glass; if that fails, replace the optical assembly |
| OneScanner does not work under Windows | Check the SCSI cable and terminator; replace the AT-to-SCSI host adapter card |
Steps are from Apple's chart, which lists them in order of likelihood; if swapping a module does not help, refit the original before trying the next step.[1][3]
SCSI problems
[edit | edit source]Logic board modification (4-bit scanner)
[edit | edit source]On a Macintosh SE/30, IIx or IIcx with other SCSI devices on the bus, an early 4-bit scanner can stop the Macintosh from starting, or lock it up during SCSI transfers. The cause is a SCSI timing error from three capacitors, CA4, CA5 and CA6, beside SCSI connector CN6 on the scanner's main logic board. Apple's fix is to remove them, which it says does not affect scanning:[4]
- Remove the main logic board and lay it on a grounded mat, wearing a wrist strap.
- Find CA4, CA5 and CA6 next to CN6.
- Cut each lead just above the board with small diagonal cutters (the Service Source method), or work each capacitor gently back and forth until it comes free (the Technical Procedures method), without touching anything else on the board.
- Trim any remaining leads, clear away debris and refit the board.[4][3]
A board without the three capacitors is the Revision B board, 661-0534.[3] Scanner driver 2.0 also corrects the problem with faster Macintosh models.[5] The OneScanner's logic board is sealed in a metal shield; Apple's instruction is to return it unopened for the modification.[4]
Termination and chain order
[edit | edit source]Apple's notes on scanner SCSI problems, mostly from users of the SE/30, IIx, IIcx and IIfx:
- Start-up failures or system errors during transfers can often be cured by changing the order of the SCSI chain, for example putting the hard disk before the scanner, by adding a second terminator, by adding or removing a SCSI extension cable, or by removing the terminator.[6]
- If the Macintosh does not see the scanner at all, Apple put it down to the impedance of the chain causing one device to be "lost", with no service procedure. Changing the impedance by adding a terminator, another SCSI device or an extension cable should bring the scanner back.[7]
- Move the terminator between the end of the cable and the scanner's spare SCSI port, try without it, and check that any internal terminators in the scanner have been removed.[8]
- On a Macintosh IIfx, use no more than two terminators on the whole chain, and only IIfx-compatible terminators.[5]
Software problems
[edit | edit source]| Symptom | Cause | Action |
|---|---|---|
| System error when saving a scan in PICT format | A settings or halftone pattern name longer than 17 characters, usually "Untitled Settings 2"[9][10] | Delete the long setting or pattern names |
| Streaks on printed scans | Background printing under MultiFinder[10] | Turn background printing off |
| Scan does not start from HyperScan | Remote scan option left on in AppleScan[9] | Press the button on the scanner, or start AppleScan to reset the option |
| AppleScan fails with 32-bit addressing | Original software is not 32-bit clean; the Centris 660AV, Quadra 660AV and 840AV run only in 32-bit mode[11] | Use Ofoto with the Apple Scanner upgrade kit |
Apple confirmed that the scanner still works with the lamp removed, which some users did to scan film on a light box laid on the glass.[12]
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 Apple Computer, Apple Scanner Technical Procedures, October 1991, Section 4 Troubleshooting: self-test p. 4.2, symptom/cure chart pp. 4.3-4.4. Hosted as File:Apple Scanner Technical Procedures (1991).pdf, PDF pp. 62-64.
- ↑ 2.0 2.1 Apple Computer, Apple Scanner Technical Procedures, October 1991, Section 3 Diagnostics: introduction and test chart pp. 3.2-3.3, test descriptions pp. 3.4-3.5, using ScanTest pp. 3.6-3.12. Hosted as File:Apple Scanner Technical Procedures (1991).pdf, PDF pp. 50-60.
- ↑ 3.0 3.1 3.2 Apple Computer, Apple Scanners Service Source (Apple Scanner and Apple OneScanner), Service Source 2.0 CD (1996). Hosted as File:Apple Scanners Service Source.pdf. Troubleshooting, general notes and symptom charts PDF pp. 10-16; Additional Procedures PDF pp. 59-74; Parts PDF pp. 76-156.
- ↑ 4.0 4.1 4.2 Apple Computer, Apple Scanner Technical Procedures, October 1991, Section 5 Additional Procedures: main logic board fuse p. 5.3, main logic board modification pp. 5.10-5.11. Hosted as File:Apple Scanner Technical Procedures (1991).pdf, PDF pp. 67 and 74-75.
- ↑ 5.0 5.1 Apple Computer, "Apple Scanner: Using with a Macintosh IIfx", Tech Info Library article 7771 (TA46390), created 2 July 1991, updated 22 December 1992. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip (retrieved 2026-10-04). Source for: no more than two terminators on a IIfx SCSI chain, IIfx-compatible terminators; older scanners' extra capacitors garble SCSI signals on faster Macintosh models; Scanner driver 2.0.
- ↑ Apple Computer, "Apple Scanner and Macintosh Start-Up Problems", Tech Info Library article 3956 (TA40009), reviewed 14 June 1989. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: start-up failures and bombs with the IIcx, IIx and SE/30; rearranging the chain, adding a terminator, adding or removing an extension cable.
- ↑ Apple Computer, "Apple Scanner: Unable To Be Recognized Problem", Tech Info Library article 5031, reviewed 9 January 1990. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "Apple Scanner: Troubleshooting SCSI Problems", Tech Info Library article 8192 (TA46680), created 14 May 1991. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.
- ↑ 9.0 9.1 Apple Computer, "Apple Scanner: Tips and Hints", Tech Info Library article 3499 (TA39325), reviewed 15 December 1988. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.
- ↑ 10.0 10.1 Apple Computer, "Apple Scanner: Four Must-Know Workarounds For Common Problems", Tech Info Library article 3331, reviewed 5 October 1988. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "Apple Scanner: Ofoto Upgrade for 32-Bit Addressing (12/93)", Tech Info Library article 10146. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.
- ↑ Apple Computer, "Apple Scanner: Controlling the Lamp During Scans", Tech Info Library article 4661 (TA40570), reviewed 17 October 1989. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.