Atari 1040STE, Field Service Manual

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J0 Joystick Port 0. The keyboard input is not functioning. If the busy input error
occurs, fix that first. Otherwise, replace the keyboard. If error persists, check
continuity from J11 , pins 1. 2, 3, 4 to J 12 pins 12, 10, 9, 8 respectively.
J1 Joystick Port 1. The keyboard input is not functioning. If the busy input error
occurs, fix that first. Otherwise, replace the keyboard. If error persists, check
continuity from J11 , pins 1, 2, 3, 4 to J12 pins 7, 5, 4, 3 respectively.
J2 Joystick Time–Out. Joystick inputs were simulated by outputting data on the
printer port and routing it via the test fixture to the joystick ports. Joystick
inputs are detected by the keyboard and sent to the CPU via the 6850. This
error can be caused by printer port failure (code P0), keyboard failure,
keyboard–CPU communication line 1, or a faulty test fixture. If the power–up
keyboard test passes, this eliminates any problem with keyboard–CPU
communication.
J3 Left Button Input. If P1 error occurs, fix that first. Otherwise replace the
keyboard. On the STE, also check continuity from J10 pin 6 to J12 pin 11.
J4 Right Button Input. If P1 error occurs, fix that first. Otherwise replace the
keyboard. On the STE, also check continuity from J10 pin 6 to J12 pin 6.
J5 Aux Joystick Direction. Game controller port (J500, J501) direction bits. 0511 is
used to drive the input via the test fixture. The hexadecimal data following
corresponds to the bits read from latches U510 and 0512, where a 1 indicates
an error. For example, 0002 indicates an error at J500 pin 3.
J6 Aux Fire Sutton. Fire buttons are read from U509. Signal is driven via the test
fixture from the output of U51 1.
J7 Paddle. The inputs are driven by either 5V/100 ohms or 5VI1 M on the test
fixture. This current charges the RC network on the STE, varying the output
pulse of the LM556. The pulse width is measured by the GSTMCU chip.
J8 Light Gun. The light gun (XPEN) input is toggled at three points on the screen
(the video address counter is used to find the position of the screen). The MCU
should return the XlY coordinates of the screen position. If the XPEN signal is
toggling and this error occurs, there is a problem with the GSTMCU.
3.18 MONOCHROME MONITOR ( H )
If this test is selected while a color monitor is connected, a message is displayed to
connect the monochrome monitor. The CPU waits for an interrupt from the
MONOMON input to the MFP, and when received (the operator connects the
monochrome monitor), changes the display to high resolution. The display screen
will reverse every two seconds. When the operator sees the display is correct, he
unplugs the monochrome monitor and re–connects the RGB monitor and the display
should return to normal
.
3.19 HARD DISK WRITE/READ (J)
This tests the hard disk interface by writing and reading one complete track of the hard disk.
It is not intended to test the hard disk drive, but tests the computer DMA circuitry. The test