Atari XMM801 Troubleshooting
Fault-finding on the Atari XMM801 printer starts with the owner's manual checks and the built-in self test, then follows the symptom table, four check flowcharts and twenty numbered check points in Atari's XMM801 Field Service Manual (CO 70435).[1][2] Cleaning, adjustments and the mechanism are on the Atari XMM801 Maintenance Guide.
 | The mains transformer, fuse and filter board are inside the case, and several of Atari's checks are made with the printer switched on. Keep clear of the mains wiring at the filter board and the power switch while measuring. |
First checks
[edit | edit source]The owner's manual lists these before anything else:[1]
- The power cord is plugged in and the Power light is on.
- The black SIO cable is firmly connected at both ends.
- The On Line light is lit; if not, press On Line.
- Paper is loaded. The paper-out sensor takes the printer off-line when there is no paper.
- Only one printer on the SIO bus is switched on.
After switching off, wait at least two seconds before switching on again, or the printer may not initialise properly.[1]
Self test
[edit | edit source]Hold down the Line Feed (LF) button while switching the printer on. It prints its character set and carries on until it is switched off. Load paper and a ribbon first.[1][2] The printout should have even print quality and even spacing between characters and lines; if it does not, check the ribbon and the paper loading first.[1]
At every switch-on the head moves to the right and back to the home position at the far left, even if it was already at home.[2] Switched on without paper, the printer lights No Paper and sounds the buzzer.[1][2]
Things that are not faults
[edit | edit source]| What happens | Why |
|---|---|
| Printing stops with about an inch of a single sheet left; the No Paper light comes on, the buzzer sounds and the printer goes off-line | The paper-out sensor working normally.[1] Sending Escape 0 (decimal 27, 48) disables it until it is re-enabled, the printer is initialised with Escape @ (27, 64) or the power is cycled; with it disabled the head prints onto the platen at the end of the sheet.[1] A reader's letter in START in 1991 gave the code as the letter O rather than zero.[3] |
| LF and FF do nothing | They work only when the printer is off-line.[1] |
| Pages start in the wrong place on fanfold paper | The top of page is set at the position of the print head when the printer is switched on.[1] |
| Print is faint or patchy | The printer has no ribbon sensor; a worn ribbon simply prints lighter.[1] |
| Garbage from Broderbund's Print Shop | Antic could not get Print Shop to work with the XMM801 in 1986.[4] XLEnt Software later sold a translator disk for it.[5] |
For AtariWriter, the owner's manual recommends the ATARI 825 printer option.[1] For Hi Tech programs such as PrintPower and Award Ware, the 1991 START letter selected the ESC2-IBM printer and turned on the Send Line Feed option.[3]
Symptom table
[edit | edit source]| Symptom | Flowchart |
|---|---|
| Printer completely dead; nothing happens at switch-on | TROUBLE-1 (Figure 23) |
| Mechanism misbehaves: motors run wrongly or only now and then, or the head and paper move without printing | TROUBLE-2 (Figure 24) |
| Paper feed and carriage work and the printer prints, but the characters are wrong | TROUBLE-3 (Figure 25) |
| Everything works except the paper feed | TROUBLE-4 (Figure 26) |
TROUBLE-1: printer completely dead
[edit | edit source]- Check the power supply voltages (REF.7-0). If they are wrong, check the supply circuit (REF.7-1) and the AC from the transformer (REF.7-2).
- Check that the CPU is running (REF.7-3 and REF.7-4). If not, check the CPU's pins (REF.7-5) and the ROM's pins (REF.7-6).
- Check the carriage motor signals A to D (REF.7-7). If they are wrong, check the home position signal (REF.7-8), then the ROM (REF.7-9).
- Check the carriage motor driver (REF.7-10) and the dot strobe from the carriage motor (REF.7-11).
- Check the printer mechanism (REF.7-12).
- Repair whatever part gave a wrong result.[2]
TROUBLE-2: mechanism misbehaves
[edit | edit source]- Switch on and watch the head return to the home position (REF.7-13). If it does not, check the CPU (REF.7-3 and REF.7-4), the CPU's pins (REF.7-5) and the ROM's pins (REF.7-6).
- Run the self test (REF.7-14). If it prints correctly, check the signals at the SIO connectors CON9 and CON10 (REF.7-15).
- If the self test fails, check the dot signals 1 to 9 at the CPU (REF.7-16), then at the head drivers (REF.7-17).
- If both are correct, check the printer mechanism (REF.7-12).[2]
TROUBLE-3: wrong characters
[edit | edit source]- Run the self test (REF.7-14). If it prints correctly, check the SIO connectors CON9 and CON10 (REF.7-15).
- If the self test is wrong, check the dot signals at the CPU (REF.7-16) and at the head drivers (REF.7-17).[2]
TROUBLE-4: no paper feed
[edit | edit source]- Check the feed motor signals A to D (REF.7-18).
- Check the feed motor driver (REF.7-19).
- Check the printer mechanism (REF.7-12).[2]
Power supply checks
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Make these checks with the printer stopped and no computer connected. The negative terminal of the bridge rectifier BD1 is a convenient ground point; if the mechanism gets in the way, lift it out of the bottom case.[2]
| Point | Expected |
|---|---|
| AC input of BD1 | About 23 V AC |
| Anode of D3 to cathode of D2 (input of the D1-D4 bridge) | About 10 V AC |
| IC7 (7805) pin 1, input, left-hand leg on the heat sink | About 11 V DC |
| IC7 pin 2, output | 5 V ±5 % |
| Emitter of T1 (2SD1392) | About 19 V DC |
| ZD1, "anode side" in the manual | 21 V DC |
The 23 V AC winding, BD1, the reservoir C2 and T1 make the 19 V supply for the head and the two motors; the 10 V AC winding, D1-D4, C1 and IC7 make the +5 V logic supply.[2] Both windings come from one transformer, so if neither AC voltage is present, check the mains fuse F1 on the filter board and the power switch. F1 is 1.0 A on 100 V and 115 V printers and T 400 mA on 220 V and 240 V printers.[2] Good AC with low DC points to the bridge rectifiers, the regulators IC7 and T1, or the reservoir capacitors C1 and C2, which are listed on the Atari XMM801 Capacitor Replacement Guide.
Check points
[edit | edit source]Atari defines "condition 1" for the static checks as the printer stopped after its power-on reset, with the head homed and the buzzer sounded, and no computer or paper connected.[2] The waveform references (Fig. a to s) are the oscilloscope photographs on pages 23 and 25 of the manual; page 24, with Fig. g to m, is missing from the hosted scan.[2]
| Ref | Check | What to see |
|---|---|---|
| REF.7-3 | Power-on reset | RESET on CPU pin 28 against +5 V on pins 63 and 64 at switch-on (Fig. s) |
| REF.7-4 | Firmware running | ALE, CPU pin 46, pulsing (Fig. a). ROM CE, pin 20, high while stopped and pulsing while printing (Fig. b) |
| REF.7-5 | CPU | RD, pin 44, pulsing while stopped (Fig. c); clock on pin 31 (Fig. d); WR, pin 45, high while stopped and pulsing while printing (Fig. e); data and address pins 55-62 and address pins 47-54 pulsing (Fig. f, g); other pins as in the table below |
| REF.7-6 | ROM | Address pins 2-10, 21 and 23-25 and data pins 11-13 and 15-19 pulsing while printing; probe the CPU or IC1 instead where easier |
| REF.7-7 | Carriage motor signals | IC6 pins 3, 6, 11 and 14: a few pulses at switch-on with the head at home, then stop; continuous pulses while the head moves (Fig. h) |
| REF.7-8 | Home position | CPU pin 21 low with the head at home, high away from it |
| REF.7-9 | ROM contents | Substitute a known good ROM |
| REF.7-10 | Carriage driver | Stepper drive pulses on IC6 pins 2, 7, 10 and 15 (Fig. i) |
| REF.7-11 | Dot strobe | With the head moving, by hand or under power, pulses on CPU pin 20 (Fig. k) and on a leg of R37 (Fig. j). Move the head by hand for a few seconds only. |
| REF.7-12 | Printer mechanism | Replace the head if the fault is in the head; otherwise inspect the mechanism for damage and replace the whole unit |
| REF.7-13 | Head homing | At switch-on the head moves right and returns home, even if it started at home |
| REF.7-14 | Self test | Switch on with LF held down |
| REF.7-15 | SIO connectors CON9 and CON10 | Data in, data out and command pulsing while printing (Fig. l, m); pin assignments below |
| REF.7-16 | Print signals at the CPU | CPU pins 9-16 pulsing while printing, pulses typically 600 µs wide (Fig. n) |
| REF.7-17 | Print signals at the drivers | Scope positive lead on the anode of ZD4, negative lead on IC3 and IC4 pins 7, 2, 15 and 10 (Fig. o). Atari's caution: the scope must be floating from ground for this check. |
| REF.7-18 | Paper feed signals | Of IC5 pins 4-7, two high and two low when not feeding; pulsing while feeding (Fig. q) |
| REF.7-19 | Paper feed motor driver | IC5 pins 10-13 while feeding (Fig. r) |
IC3 and IC4 are the head drivers (M54567P), IC6 the carriage motor driver and IC5 (M54523P) the paper feed motor driver; LSI1 is the µPD7811 CPU and ROM1 the firmware EPROM.[2] The manual calls the ROM a 2764 in the parts list and a 27128 in REF.7-6 and REF.7-9, so check the part fitted before probing by pin number.[2]
CPU pin levels under condition 1
[edit | edit source]| Pins | Level |
|---|---|
| 1, 3, 5, 6, 8, 18, 19, 21, 22, 23, 24, 26, 29, 32, 33, 38 | Low |
| 2, 4, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 20, 25, 28, 34, 35, 36, 37, 39, 40, 63, 64 | High |
| 42, 43 | High (+5 V) |
| 27, 52, 53 | High, pulsing |
| 41 | Floating |
Under the same condition the ROM's pins 1, 26, 27 and 28 sit at +5 V and pin 14 at ground; the table shows pin 20 pulsing, although REF.7-4 says CE stays high while the printer is stopped.[2]
SIO connector
[edit | edit source]The two 13-pin connectors CON9 and CON10 on the interface board are wired pin for pin to each other, so either can go to the computer and the other on to the next device.[2]
| Pin | Signal | Notes |
|---|---|---|
| 3 | Data in | To the computer |
| 4 | Signal ground | |
| 5 | Data out | From the computer |
| 6 | Signal ground | |
| 7 | Command | From the computer; low while it sends a command frame to the printer |
| 10 | Ready | From the computer; high when it is ready |
| 1, 2, 8, 9, 11, 12, 13 | Not used by the printer | Passed through between the two connectors |
Related pages
[edit | edit source]- Atari XMM801
- Atari XMM801 Maintenance Guide
- Atari XMM801 Capacitor Replacement Guide
- Atari XMM801 Documentation
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Atari Corp., Atari XMM801 Dot-Matrix Graphics Printer Owner's Manual, C025959-001 Rev. A, 1985: loading paper and top of page (pp. 4-7), control panel and self test (pp. 8-9), power-up defaults (p. 17), initialise and paper-out sensor codes (pp. 39-40), troubleshooting (pp. 55-56), serial interface (p. 73). Hosted here as File:Atari XMM801 Owner's Manual C025959-001.pdf.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Atari Corp., XMM801 Field Service Manual, CO 70435, October 1985: basic structure (p. 3), power-on timing chart (p. 7), power supply circuits (p. 8), main control board circuit and layout (pp. 10-11), symptom table (p. 14), check flowcharts TROUBLE-1 to TROUBLE-4 (pp. 15-18), check points REF.7-0 to REF.7-19 (pp. 19-22), typical waveforms (pp. 23 and 25), parts list (pp. 27-28). Hosted here as File:Atari XMM801 Field Service Manual C070435.pdf.
- ↑ 3.0 3.1 Vito A. Raia, "Exasperating XMM801", I/O Board, START vol. 5 no. 5, January 1991. atarimagazines.com. Reader's tips: Hi Tech programs set to the ESC2-IBM printer with Send Line Feed; single sheets stop at 60 lines; paper-out detector code.
- ↑ Gregg Pearlman, "Two New Atari Printers", Antic vol. 5 no. 8, December 1986. atarimagazines.com. Software compatibility tests (Print Shop, Lister Plus, Epson drivers).
- ↑ "XMM801 woes", I/O Board, Antic vol. 6 no. 10, February 1988. atarimagazines.com. Print Shop garbage characters and the XLEnt translator disk.