Atari 1027 Troubleshooting

Atari 1027 printer

Fault-finding on the Atari 1027 Letter Quality Printer follows the tests, symptom checklist and diagnostic table in Atari's 1027 Printer Field Service Manual (FD100670 Rev. 01). Cleaning, oiling and the ink roller are on the Atari 1027 Maintenance Guide.

Power-up

Switch the printer on. During initialisation the type wheel assembly moves to the left end of the carriage, the wheel rotates, then the assembly moves a short distance right and stops. If it does not, the symptom checklist points to the sensors:

Initialisation faults (FD100670 p. 4-2)

Symptom at power-on reset	Possible cause	Check
Hammer assembly does not go to its initial position	Hammer move sensor unit	Signal at LSI (A1) pin 35
Type wheel assembly does not go to its initial position	Sensor (A) unit	Signal at A1 pin 36
Type wheel keeps rotating	Sensor (A) unit	Signal at A1 pin 39
Type wheel does not rotate enough	Sensor (A) unit	Signal at A1 pin 1

If there is no signal, troubleshoot and repair the sensor circuit.

Tests

Atari's CPS diagnostic diskette carries the program T1027.BAS (FD100577 Rev. 02), run with RUN "D1:T1027.BAS". Its menu offers an all-function test, the standard and international character sets, an underline check, a direction print check, a carriage return loop, a horizontal step motor loop and a selective character loop. The two loops are there so that the motors and logic can be checked with an oscilloscope.

The character skew test prints 30 lines of the letter E. Rule vertical lines between the columns: if the letters in a column are not directly under each other, run the test again, and if they are still misaligned Atari replaces the printer mechanism.

10 OPEN #1,8,0,"P:"
20 FOR X=1 TO 30
30 FOR Y=1 TO 70
40 ? #1;"E";
50 NEXT Y
55 ? #1;CHR$(127)
60 NEXT X
70 CLOSE #1
80 STOP
90 GOTO 10

Never run the tests without paper: it can damage the type wheel and smear the next sheets.

Symptom checklist

Atari 1027 symptom checklist (FD100670 pp. 4-1 and 4-2)

Symptom	Possible cause	Repair
Hammer pulse motor, wheel select pulse motor, DC motor and solenoid all work but nothing prints	Ink roll not mounted properly, or the ink is exhausted	Mount the ink roll properly or replace it
Hammer pulse motor does not move properly	Foreign matter between the gears	Turn the pulley gear by hand and remove the foreign matter
	Hammer pulse motor lead cut	Repair if possible. Check for current to each phase of the motor (p. 4-3): if present, replace the printer mechanism; if absent, troubleshoot and repair the drive
Wheel select pulse motor does not move properly	Wheel select pulse motor lead cut	Repair if possible. Check for current to each phase of the motor (p. 4-3): if present, replace the printer mechanism; if absent, troubleshoot and repair the drive
DC motor does not rotate (the manual lists the solenoid lead under the same heading)	Foreign matter between the gears	Turn the pulley gear by hand and remove the foreign matter
	DC motor lead cut	Repair if possible. Check for current to the motor (p. 4-3): if present, replace the printer mechanism; if absent, troubleshoot and repair
	Solenoid lead cut	Repair if possible. Check for current to the solenoid (p. 4-3): if present, replace the printer mechanism; if absent, troubleshoot and repair
Paper does not feed, printing otherwise normal	Paper lock/release lever in the release position	Check the lever
Prints the preceding character on the same character ring	The electrolytic capacitor lead of the DC motor has come off the motor terminal	Resolder the lead

Diagnostic table

Table 4-1, where to look for signals (FD100670 p. 4-3)

Mechanism part	Test option	Signal at
Wheel select motor leads WA-WD	7	Connector 1, pins 9-12
Hammer motor leads HA-HD	6	Connector 1, pins 3-6
DC motor (MT)	8	Connector 2, pin 2
Hammer select solenoid (HS, solenoid B)	5	Connector 2, pin 4
Character select solenoid (CS, solenoid A)	5	Connector 2, pin 6
Wheel timing (WT)	8	Connector 3, pin 4
Zero timing sensor (ZT)	1, 2 or 3	Connector 3, pin 2
Hammer home position (HHP)	7	Connector 3, pin 9
Wheel home position (WHP)	7	Connector 3, pin 6

The drive timing gives a check on each signal: the stepper clock pulses are about 5 ms, solenoid B gets a single pulse of about 10 ms from A1 pin 22, solenoid A one of about 8 ms from A1 pin 21, and the DC motor runs while A1 pin 23 is low.

Power

The adaptor delivers 9.5 V AC at 40 VA, and the board rectifies it (D1, with C1, a 15,000 µF 25 V capacitor) and regulates it to 5 V ±5 % (A5, logic and sensors) and 6 V ±10 % (A4, motors and solenoids). Atari's schematic shows a 5 A fuse inside the adaptor. The power-on reset holds the 8049 low for about 100 ms, and the crystal runs at 6 MHz.

Print quality

• Faint or faded print: worn or damaged ink roller.
• Some characters dark and others barely readable: the ink roller is not seated firmly.
• A jumbled line of unrelated characters: the type wheel has lost its alignment at the left of the line; switch off and on to realign it.
• Missing or broken characters: the rubber type wheel may have perished. Owners have found old wheels soft and breaking up.

Pauses with AtariWriter

Used with AtariWriter, the 1027 sometimes stops for about three minutes and then carries on as if nothing had happened. Page 6 reported this in 1985 without a known cause or cure.

Related pages

• Atari 1027
• Atari 1027 Maintenance Guide
• Atari 1027 Documentation