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Sony UP895 Service Manual - Page 36

Head Up and Down Control, 4-4-5. Monitor of Door Sensor, system control IC304.

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4-4-4. Head Up and Down Control A head up/down DC motor is driven by its driving circuit (IC400). The DC motor can rotate in the forward and reverse directions. It is controlled by a system control (IC304). The head also has three positions. The head position is detected using optical head position sensors (photo-interrupters PH21 and PH22) and read by a system control (IC304). Operation of head up/down motor Head motor UP DOWN STOP IC304-28pin L H H IC304-27pin H L H Operation Raises the head. Lowers the head. Stop Condition of head position sensor Position TOP MIDDLE BOTTOM IC304-17pin H L H IC304-16pin H H L Condition Unlocks the door. Wait (Usual) Print 4-4-5. Monitor of Door Sensor The door position is detected using an optical door position sensor (photo-interrupter PH32) and read by a system control (IC304). Condition of door position sensor Position CLOSE OPEN IC304-20pin L H Condition The door is closed. The door is open. 4-4-6. Monitor of Paper Sensor Whether thermosensible paper is properly put in this unit is detected using two pairs of optical paper sensors (phototransistors PH31 and PH12) and read by a system control (IC304). Condition of paper sensor IC304-18pin H For except "H" IC304-19pin H For except "H" Condition Paper exists. No paper 4-10 UP-895/(E)

Section	Page
Cover	1
Table of Contents	3
1.Operating Instructions	7
2.Service Information	17
2-1. Board Layout	17
2-2. Disassembly	17
2-3. Removal of Major Parts	18
2-3-1. Removal of Mechanical Block	18
2-3-2. Removal of MA-99 Board	19
2-3-3. Removal of Switching Regulator	19
2-3-4. Removal of Thermal Head	20
2-4. Tightening the Screws	21
2-5. Installation of Fan Motor	22
3.Electrical Alignment	23
3-1. AGC Adjustment	23
3-2. Video Level Adjustment	23
3-3. Brightness and Contrast Adjustment	24
3-4. Head Voltage Adjustment	25
3-5. Initialization of Print Count History	25
4.Circuit Operation Description	27
4-1. Video Circuit	29
4-1-1. BNC Input Connector - Trap Filter Circuit	29
4-1-2. nC-SYNC Generator Circuit	29
4-1-3. AGC Circuit	29
4-1-4. Brightness and Contrast Control	29
4-1-5. A/D Conversion and D/A Conversion	29
4-2. Clock Generator Circuit	30
4-3. Memory and Head Control Circuit	30
4-3-1. Reading the Serial Data from System Control	31
4-3-2. Writing in Frame Memory	31
4-3-3. Transfer from Frame Memory to Line Memory	31
4-3-4. Thermal Head Control and One-Line Memory	31
4-4. System Control Section	34
4-4-1. Reading of Keys	34
4-4-2. Reading of Function Switches	34
4-4-3. Platen Motor Control	35
4-4-4. Head Up and Down Control	36
4-4-5. Monitor of Door Sensor	36
4-4-6. Monitor of Paper Sensor	36
4-4-7. Monitor of Head Temperature Sensor	37
4-4-8. Control of Head Fan Motor (for Head Cooling)	37
4-4-9. Control of Video Circuit Section	37
4-4-10. Control of Memory and Head Control Circuit	38
4-4-11. Gamma Correction and Thermal Storage Correction	39
4-4-12. Discrimination of Video Signal to be Input	39
4-4-13. Remote Interface	39
4-4-14. Storage of Print Count History	39
4-5. Thermal Head Section	40
4-5-1. Structure	40
4-5-2. Basic Operation	41
4-5-3. Stair Generation	41
4-5-4. Temperature Correction	42
4-5-5. Line Count Correction	42
5.Troubleshooting	43
5-1. Print is Faulty	43
5-2. Print is Too Dark or Too Light	44
5-3. “Paper Sensor” is Out of Order	45
5-4. Head Operation (Up & Down) is Out of Order	46
5-5. Paper Feeding is Out of Order	47
5-6. Door (Opening and Closing) is Out of Order	48
6.Service Mode (Self-diagnostic Function)	49
6-1 Printing the Test Pattern	49
6-2. Up/Down Operation of Head	50
6-3. Feed Operation	50
6-4. Display and Clearing of Print Sheet History	51
7.Semiconductor Pin Assignments	53
8.Spare Parts	55
8-1. Notes on Repair Parts	55
8-2. Exploded Views	56
8-3. Electrical Parts List	61
9.Block Diagram	69
Overall	69
10.Schematic Diagrams and Board Layouts	71
Frame	72
KY-454	73
SE-531	73
SE-532	73
SU-52	73