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TROUBLESHOOTING
MI ROPRO ESSOR HIP ( PU) OPERATION
Verify the processor is functioning by checking the signals
on the address lines (pins 10 thru 24 of C U600) and the data
lines (pins 41 thru 56) using a logic probe or a scope. f a logic
probe is used, refer to the "Logic Chart" for the correct
readings.
f a scope is used, the waveforms on the address
lines (except pins 22 and 23 which have no signal in Power Up
mode) should be similar to Figure 1. The waveforms on the
data lines should be similar to Figure 2.
Figure 1
5V
2ms
0V
DC
Reference
f the processor is not functioning, check the source voltages
at pins 1, 2, 27, 33 and 59. Check the 48 MHz Oscillator
Crystal (Y600) by checking the waveforms at pins 1 and 18 of
C U601. The frequency at pin 1 of C U601 should measure
12.00MHz. Check the phase relationships of the
01, 02, 03
and 04 clocks at pins 12,11,8 and 9 of C U601 (See Figure 3).
Check the phase relationships of the 01, 02, 03 and 04
clocks at pins 14, 15, 7 and 6 of C U601 (See Figure 4). Use a
logic probe and check the readings at pins 4 thru 9, 25, 28, 29
and 61 thru 64 of C U600 (See "Logic Chart").
01
02
03
04
Figure 4
U601
P N 14
P N 15
P N 7
P N 6
.2/xs
RYSTAL OS ILLATORS
Connect a frequency counter to pin 1 of C U601 to check the
48 MHz oscillator. The frequency should read 12.00 MHz.
Connect a frequency counter to pin 39 of C U100 to check
the 10.7 MHz oscillator. The frequency should read 10.738635
MHz. The frequency of the 10.7 MHz oscillator can be ad
justed by Coil L100.
VIDEO SIGNALS
Verify the operation of the video circuits by checking the
waveforms at pin 36 of C U100 and pin 4 of Jack J201. f the
waveform is absent at pin 36 of C U100, check the 10.7 MHz
oscillator at pins 39 and 40 of C U100 and check pins 1 thru
38 with a logic probe (See the "Logic Chart"). f the waveform
at pin 4 of J201 is absent, check the voltages and com
ponents associated with Amp Transistor (Q200) and Predriver
Transistor (Q201).
SOUND
Type in and run the following program if there is no sound.
Check for a .7V p-p waveform at pin 7 of C U511.
1 CALL SOUND (-400,200,2)
2 GOTO 1
f the waveform is present, check Capacitors C502, C503,
C206 and C208 and Coil L201. f the waveform is absent, use
a logic probe and check pins 1 thru 14 of C U511. The
readings should be the same as given in the "Logic Chart",
except pin 6 will show pulses while the program is running.
Check the clock waveform on pin 14 with a scope.
KEYBOARD
The computer comes up with the main title screen displayed
on the monitor, but the keyboard has no effect when the keys
are pressed. Check the waveforms on pins 1,3, 6, 7, 9, 10, 11,
12 and 13 of C U302 and pins 6, 7, 8, 9, 20, 31,32, 33 and 34 of
C U300. Use a logic probe and check the readings on pins 1
thru 5, 10, 11, 17, 18, 24, 25, 35, 36, 39 and 40 of C U300 (See
"Logic Chart").
14
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