HP HP-75D Handheld BASIC Computer Manuals

Manuals and User Guides for HP HP-75D Handheld BASIC Computer. We have 1 HP HP-75D Handheld BASIC Computer manual available for free PDF download: Service Manual

HP HP-75D Service Manual (198 pages)

Brand: HP | Category: Desktop | Size: 2 MB

Contents
2
Illustrations List
7
Tables List
9
General Information
10
Product Description
10
Specifications
12
Identification
14
Safety Consideration
15
Servicing
17
Using this Manual
18
Recommended Tools
18
Troubleshooting
22
System Overview
23
Block Diagram
25
Troubleshooting Overview
28
Keyboard Assembly Propped up View
29
Removing and Inserting Socketed Ics
30
Setup
33
Socketed Ics
33
Initial Troubleshooting
34
Ics Indicated by {CPU BAD? N or RAM BAD!} Message
37
No Turn-On
38
Power Supply, PWO, and Clock Test Points
40
Service Roms
41
Clock Waveforms
41
Self-Test
42
Running a Service ROM Test
43
System Self-Test Results
43
Error Messages
45
Service ROM Tests
46
Troubleshooting with the System Test
47
Results of the System Test
47
RAM/ROM Test Diagnosis
48
Beeper Test Diagnosis
49
CRT Test Diagnosis
49
Timer Test Diagnosis
50
Keyboard Test Diagnosis
50
Service ROM IC Messages
51
Troubleshooting with the Cycle Test
53
How to Run the Cycle Test
53
Using the Heat Test
53
Results of the Heat Test
54
Troubleshooting with the CPU Test
54
Results of the CPU Test
55
Troubleshooting the Control and Bus Lines
55
Troubleshooting with the RAM Test
56
Control of Bus Line Failure Isolation
56
Results of the RAM Test
57
Troubleshooting with the ROM Test
57
Results of the ROM Test
58
Troubleshooting with the External ROM Test
58
Results of the External ROM Test
59
Keyboard Troubleshooting
60
How to Run the Keyboard Test
60
Enhancement ROM Codes
60
Results of the Keyboard Test
61
Key Sequence for Keyboard Test
62
No Key Entry
69
Wrong Character Entered
70
Key Stuck
73
Mnemonics and Key Lines for Keys Expected
74
Key(S) Corresponding to Character Entered
79
Troubleshooting with the Timer Test
84
Results of the Timer Test
84
Troubleshooting the CRT
84
Results of the CRT Test
85
CRT Test Patterns
87
CRT Adjustments
89
Checking Whether the Display Is Pincushioned
92
CRT Test Pattern Overlay in Position
92
CRT Adjustment Procedures
93
Skew
94
Horizontal Centering
97
Size
98
Vertical Centering and Height
98
Power Supply Troubleshooting
99
Focus
99
PWO and Clock Failure Isolation
102
Troubleshooting with the Short HP-IB Test
104
Results of the Short HP-IB Test
104
Troubleshooting with the Long HP-IB Test
105
Results of the Long HP-IB Test
106
Troubleshooting with the External RAM Test
106
Results of the External RAM Test
107
Troubleshooting with the Beeper Test
108
Results of the Beeper Test
108
Using the QA Test
108
Results of the QA Test
109
Disassembly and Reassembly
110
Removing and Tightening Screws
111
Cable Interconnections
112
Special Handling for Keyboard Assembly Cables
112
Connecting a Cable
112
Removing a Trapped Cable
113
Aligning Cable Contacts
113
Cable Connected Properly
114
Cable Misaligned
114
Cable Connected with Edge Folded over
115
Replacing Assemblies and Case Parts
116
Separating the Top Case from the Bottom Case
118
Replacing the Keyboard Assembly
121
Replacing a Keycap
123
Keyboard View
124
Replacing the Space Bar
125
Replacing a Plunger and Spring
127
Replacing the [Caps Lock] Key Mechanism
129
Replacing Key Contacts
131
Replacing a Keyboard Hinge
134
Cleaning Key Contacts
135
Replacing the Logic One PCA
136
Replacing the Logic Two PCA
138
Replacing the Power Supply PCA
140
Replacing the CRT PCA
142
Replacing the CRT Assembly
144
Replacing the Back Panel Assembly
145
Replacing the I/O PCA
147
Replacing the HP-IB PCA
149
Replacing Parts of the Top Case Assembly
151
Replacing Parts of the Bottom Case Assembly
153
To Replace the Brightness Control
154
To Replace the Power Light
155
Attaching the Top Case to the Bottom Case
158
Replaceable Parts
160
Keyboard Assembly Exploded View
167
Exploded Diagrams
174
Schematic Diagrams
180

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