Check Points For Repair - Atari XMM801 Field Service Manual

2. Check Points for Repair

The followings are reflected to the markings on the check flow
charts on paragraph l.
In this description, there are the explanations as refer to
FIG. a,b,c,.... showing the tested wave form on scope that can
be compared with the same index in paragraph 3."Typical wave
form of signals".
When the checking operation is disturbed by the printer mecha-
nism, it should be removed from the bottom case. The (-) leg
of Diode BD-1 is useful as GND terminal for testing.
REF.7-0 Check of Voltage on Power Supply. Printer is stopped.
Anode side of zener diode ZD1 should show the
voltage of DC 21V.
-The PIN 2 of regulator IC7 should show DC 5V ±5% (on
the main control board.
REF.7-1 Check Power Supply Circuits and Devices while the
printer is stopped.
-The "1" leg of IC-7, located left hand of heat sink
Should show the voltage of approx. DC 11V.
-The "E" leg of transistor T1 should show the voltage
of about DC 19V.
-The "E" leg of transistor T3 should show the voltage
of about DC 1V.
REF.7-2 Check of AC Voltage, while the printer is stopped.
Without the Host.
-Input of diode BD-1 should show the sine wave with
voltage range of approx. AC 23V.
-Between the anode of D3 and the cathode of D2, it
should show the sine wave with voltage range of
approx. AC 10V.
REF.7-3 Check for pulses at power-on reset time.
-Relation between "DC 5V" on Pin 63, 64 and "RESET" on
Pin 28 of CPU (7811) should show a the pulse wave,
refer to FIGURE s. at turning power switch on.
REF.7-4 Check "if software is running".
-Signal ALE, on Pin 46 of CPU (7811) 1 should show the
pulse ;nave, refer to FIG. a.
-Signal CE, Pin 20 ROM (2764) should show:
high level while the printer is stopped.
Pulse wave, refer to FIG. b-similar wave, while the
printer is running.
RFF.7-5 Check around main CPU (7811).
-Signal RD, on Pin 44 of main CPU (7811) should show
the pulse wave, refer to FIG. c, while the printer is
stopped.
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