Apple Personal Modem Troubleshooting Guide
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Apple's service procedure for the Apple Personal Modem is a power test, a computer test and an analogue loopback self-test, followed by exchange of the whole modem. Apple's technical procedures say most modem problems arise during installation, and that others appear only at certain speeds or in certain modes, so check the software settings before suspecting the hardware.[1] The modem has no DIP switches; speed (110, 300 or 1200 baud), parity and duplex all come from the software.[1]
Equipment
[edit | edit source]Apple lists the modem and its user's manual, a telephone line, the right interface cable, and one of these computer and software pairs: an Apple II family computer with Access II or AppleTerm, a Macintosh with MacTerminal, or a Macintosh XL with MacTerminal or LisaTerminal.[1] On an Apple II, IIe or II Plus the modem connects through a Super Serial Card; set its DIP switches as the modem manual describes.[1]
Power test
[edit | edit source]The modem beeps when it is first plugged in, which shows that it is receiving power and its self-test has passed.[1][2] If there is no beep:
- Turn the volume control clockwise and plug the modem in again.
- Push the power connector (plug head) fully home until it clicks, and plug the modem in again.
- Exchange the modem and try again.[1]
Computer test
[edit | edit source]- Load the communications software, switch the computer on and check the configuration settings.
- Enter terminal mode, type AT and press Return. The screen should show OK.
- If there is no OK after several tries, check that the software is set to 110, 300 or 1200 baud.
- Switch off, unplug the modem, and check the cable and connections (and the Super Serial Card switches on an Apple II).
- Plug the modem in, start the software, enter terminal mode and type AT again. If there is still no OK, exchange the modem.[1]
On a Macintosh Plus, the original MacTerminal does not assert DTR, and without DTR the modem ignores the computer. Use MacTerminal 2.0 with the newer System and Finder.[3]
Analogue loopback self-test
[edit | edit source]- Load the software and enter terminal mode.
- Type ATS16=1D and press Return. The speaker comes on with a dial tone or a high-pitched tone, and the screen shows CONNECT or CONNECT 1200.
- Type a short message. The modem loops the characters back, so if they appear on screen the modem is working. The Return key may not move the cursor to a new line.
- Wait one second and type +++ to return to command mode. The screen shows OK.
- Type ATZ and press Return to leave self-test mode. The screen shows OK.
If the test fails, exchange the modem and run the test again.[1]
Symptom chart
[edit | edit source]| Symptom | Actions, in order |
|---|---|
| No beep when plugged in | Turn the volume control clockwise and plug the modem in again; check that the power connector is firmly in place; replace the power connector; replace the modem |
| No sound while the modem is operating | Turn the volume control clockwise and plug the modem in again; replace the modem |
Source: the 1995 Service Source modems chapter.[4]
Known faults and configuration problems
[edit | edit source]| Symptom | Cause | Action |
|---|---|---|
| Modem does not answer incoming calls (for example through AppleLine) | Auto-answer register S0 defaults to 0 on this modem[5] | Send ATS0=1 before connecting; it stays set until the modem is reset or powered down. For AppleLine use cable 590-0331 with the modem eliminator cable 590-0029 |
| Software reports no carrier | Carrier-detect response time (S9) is fixed at 0.6 seconds, too short for some programs[6] | Lengthen the carrier wait with ATS7x (x from 1 to 255 seconds; default 30) |
| No response on a Macintosh Plus | Old MacTerminal does not raise DTR[3] | Use MacTerminal 2.0 |
| HyperCard's dial command will not stay off-hook after dialling (trailing ";" ignored) | Wrong surface-mount resistors at R106 and R107 on modems with serial numbers C621301 to C745577[7] | Try a modem outside that serial range; Apple service providers could correct the resistors |
| Pins do not match the manual | Figure F-1 on page 84 of the user's manual is wrong[8] | Use the corrected numbering on the main page |
| Will not work on a non-US telephone line | Bell 103 and 212A are US standards[9] | Use a modem approved for that country |
Apple's article on the HyperCard fault contradicts itself on the resistor value. Its text says a supplier fitted 2.3 Ω resistors where 4.7 Ω parts belonged, but its marking key calls 4R7 incorrect and 2R3 correct.[7] Check R106 and R107 against a modem outside the affected serial range before changing anything.
Service parts
[edit | edit source]The modem is two modules: the main body, 661-0313, which is supplied with a plug head, and the power connector plug head, 933-0001, available on its own. If the body is faulty, Apple's rule was to return both pieces; if only the plug head is faulty, exchange just the head.[1][4] Neither Apple document gives an internal take-apart procedure, a schematic or a board-level parts list for this modem.
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Apple Computer, Apple Service Technical Procedures: Cross Family Peripherals, Volume One (part number 072-0230, March 1991 build), Modems tab, section 2, "Apple Personal Modem", pp. 2.1-2.5 (rev. April 1987), and Illustrated Parts List, Figure 3, pp. IPL.6-IPL.7 (rev. December 1987). Hosted as File:Apple Technical Procedures Modems (1991).pdf, PDF pp. 15-19 and 57-58. Source for: the introduction, equipment list, power test, computer test, self-test mode, the two-module exchange rule and part numbers.
- ↑ Apple Computer, "Apple Personal Modem: Specifications (Discontinued)", Tech Info Library article 1303. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip (retrieved 2026-10-04). Source for: the power-up self-test and beep, which cannot be disabled; the indicator light acting as data carrier detect.
- ↑ 3.0 3.1 Apple Computer, "Macintosh Plus P/C: No Response From Apple Personal Modem", Tech Info Library article 1884 (TA34639), reviewed 10 March 1988. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: the old serial driver does not raise DTR; MacTerminal 2.0 cures it.
- ↑ 4.0 4.1 Apple Computer, Service Source: Modems (PDF dated November 1995, from the Service Source 2.5 CD of 1997). Hosted as File:Apple Service Source Modems (1995).pdf. Take Apart, Apple Personal Modem, p. 7; Troubleshooting, Symptom Charts, Apple Personal Modem, p. 3.
- ↑ Apple Computer, "Apple Personal Modem: Making it Work with AppleLine", Tech Info Library article 2220 (TA36944), 1989. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: S0 defaults to 0; setting S0=1; the cable pair 590-0331 and 590-0029 for AppleLine.
- ↑ Apple Computer, "Apple Personal Modem: Carrier detect", Tech Info Library article 1981 (TA35502). Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: S9 fixed; ATS7x with x from 1 to 255; default 30 seconds.
- ↑ 7.0 7.1 Apple Computer, "HyperCard: Problem With Dial Command and Apple Personal Modems", Tech Info Library article 4239 (TA40206), reviewed 17 August 1989. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: the serial-number range, R106 and R107, the 2.3 and 4.7 ohm values and markings, repair by an Apple service provider.
- ↑ Apple Computer, "Apple Personal Modem: Correction to User's Manual", Tech Info Library article 2807 (TA37941), reviewed 30 March 1988. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip. Source for: corrected socket numbering, rows 8-7-6, 5-4-3 and 2-1 seen from the back of the modem.
- ↑ Apple Computer, "Apple Personal Modem: Can't Be Used In All Countries", Tech Info Library article 2874 (TA37982), reviewed 13 April 1988. Archive.org item APPLE_TIL_ARTICLES, file TIL00001_to_TIL60496.zip.