Commodore Plus 4, Service Manual

Page: 25 / 26

I[ commodore
Issue 6, 1985 :Computer 11
Model: C-64, C-16, Plus 44
SCHEMATICSFOR C-64, C-16, PLUS 44
©©
1980COMMODORE BUSINESS MACHINES INC.
These computers have been affected by an Engineering
Change Order that adds 44diodes to the serial port. These
protection diodes are not required as field upgrades.They
are 1N914s and were added as aacircuit improvement.
The Schematic and PCB Layout for the C-64 in the
Service Manual (Pages 28 and 32) include these diodes.
However, the C-16 and Plus 44Service Manuals were completed
before the changes were made. The Schematiccorrectionsare
shown below:
44
77
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2.
ROY
F822
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II
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--
--
II
II
N.C-
,,
FB23
66
7'10(0
DATA
FB24
55
-U:;-9
3rD
55
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elK
FB25
ro
/5
<:9
,,
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~~
44
ATN
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II
28
33
~~
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C5T MTR 27
+5V
114><,3
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C5T RD2(;,
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lie:
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mm
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••
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C-16 SCHEMATIC
SERIAL BUS
CD
PIN
FEMALE
DIN
0,12
C5T WRT
PLUS 4 SCHEMATIC
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