Panasonic KX-FT931LA-B User manual

© 1995 Matsushita Electric Industrial Co., Ltd. All
rights reserved. Unauthorized copying and distribu-
tion is a violation of law.
Order No.KMF0605960CE
Personal Facsimile
KX-FT931LA-B
B: Black Version
(for Latin America)

2
KX-FT931LA-B
TABLE OF CONTENTS
PAGE PAGE
1 Safety Precautions -----------------------------------------------3
1.1. For Service Technicians ----------------------------------3
1.2. AC Caution---------------------------------------------------4
1.3. Personal Safety Precautions ----------------------------5
1.4. Service Precautions ---------------------------------------6
2Warning--------------------------------------------------------------7
2.1. About Lead Free Solder (PbF: Pb free) --------------7
2.2. Insulation Resistance Test -------------------------------7
2.3. Battery Caution ---------------------------------------------7
3 Specifications ------------------------------------------------------8
4 General/Introduction---------------------------------------------9
4.1. Optional Accessories--------------------------------------9
4.2. Translation Lists --------------------------------------------9
5Features------------------------------------------------------------ 10
5.1. ---------------------------------------------------------------- 10
6 Technical Descriptions---------------------------------------- 11
6.1. Connection Diagram------------------------------------- 11
6.2. General Block Diagram--------------------------------- 12
6.3. Control Section ------------------------------------------- 14
6.4. Facsimile Section ---------------------------------------- 20
6.5. Sensors and Switches ---------------------------------- 26
6.6. Modem Section ------------------------------------------- 30
6.7. NCU Section----------------------------------------------- 37
6.8. ITS (Integrated Telephone System) and
Monitor Section ------------------------------------------- 41
6.9. ATAS (Automatic Telephone Answering
System) Section ------------------------------------------ 41
6.10. Operation Board Section ------------------------------- 43
6.11. LCD Section ----------------------------------------------- 44
6.12. Power Supply Board Section-------------------------- 45
7 Location of Controls and Components------------------ 48
7.1. Overview --------------------------------------------------- 48
7.2. Control Panel---------------------------------------------- 49
8 Installation Instructions--------------------------------------- 50
8.1. Installation Space ---------------------------------------- 50
8.2. Connections ----------------------------------------------- 50
8.3. Installing the Recording Paper------------------------ 51
9 Operation Instructions ---------------------------------------- 52
9.1. Setting Your Logo ---------------------------------------- 52
10 Test Mode---------------------------------------------------------- 54
10.1. DTMF Single Tone Transmit Selection ------------- 55
10.2. Button Code Table --------------------------------------- 55
10.3. Print Test Pattern----------------------------------------- 55
11 Service Mode ----------------------------------------------------- 56
11.1. Programming and Lists --------------------------------- 56
11.2. The Example of the Printed List ---------------------- 59
12 Troubleshooting Guide---------------------------------------- 63
12.1. Troubleshooting summary ----------------------------- 63
12.2. Error Messages-Display -------------------------------- 64
12.3. Error Messages Report--------------------------------- 65
12.4. Remote Programming----------------------------------- 87
12.5. Troubleshooting Details -------------------------------- 90
13 Service Fixture & Tools ------------------------------------- 116
14 Disassembly and Assembly Instructions ------------- 117
14.1. Disassembly Flowchart --------------------------------117
14.2. Disassembly Procedurel-------------------------------119
15 Maintenance ---------------------------------------------------- 128
15.1. Maintenance Items and Componet Locations -- 128
15.2. Gear Section---------------------------------------------130
15.3. Jams -------------------------------------------------------136
15.4. Cleaning---------------------------------------------------137
16 Miscellaneous --------------------------------------------------138
16.1. Terninal Guide of the ICs, Transistors and
Diodes -----------------------------------------------------138
16.2. How to Replace the Flat Package IC --------------140
16.3. Test Chart------------------------------------------------142
17 Schematic Diagram -------------------------------------------145
17.1. Digital Board ---------------------------------------------145
17.2. Analog Board --------------------------------------------147
17.3. Operation Board ----------------------------------------149
17.4. Power Supply Board -----------------------------------150
18 Printed Circuit Board-----------------------------------------152
18.1. Digital Board ---------------------------------------------152
18.2. Analogue Board ----------------------------------------154
18.3. Operation Board ----------------------------------------156
18.4. Power Supply Board -----------------------------------158
19 Appendix Information of Schematic Diagram -------159
20 Exploded View and Replacement Parts List---------- 161
20.1. Cabinet, Mechanical and Electrical Parts
Location ---------------------------------------------------161
20.2. Replacement Parts List -------------------------------167
20.3. Cabinet and Mechaical Parts ------------------------167
20.4. Digital Board Parts -------------------------------------168
20.5. Analog Board Parts ------------------------------------170
20.6. Operation Board Parts---------------------------------171
20.7. Power Supply Board Parts ---------------------------172
20.8. Fixtures and Tools --------------------------------------173

3
KX-FT931LA-B
1 Safety Precautions
1. Before servicing, unplug the AC power cord to prevent an electric shock.
2. When replacing parts, use only the manufacturer's recommended components.
3. Check the condition of the power cord. Replace if wear or damage is evident.
4. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc.
5. Before returning the serviced equipment to the customer, be sure to perform the following insulation resistance test to prevent
the customer from being exposed to shock hazards.
1.1. For Service Technicians
ICs and LSIs are vulnerable to static electricity.
When repairing, the following precautions will help prevent recurring malfunctions.
1. Cover the plastic part’s boxes with aluminum foil.
2. Ground the soldering irons.
3. Use a conductive mat on the worktable.
4. Do not touch the IC or LSI pins with bare fingers.
1.1.1. Suggested PBF Sloder
There are several types of PbF solder available commercially. While this product is manufactured using Tin, Silver, and Copper,
(Sn+Ag+Cu), you can also use Tin and Copper, (Sn+Cu), or Tin, Zinc, and Bismuth, (Sn+Zn+Bi). Please check the manufac-
turer’s specific instructions for the melting points of their products and any precautions for using their product with other
materials.
The following lead free (PbF) solder wire sizes are recommended for service of this product: 0.3mm, 0.6mm and 1.0mm.

4
KX-FT931LA-B
1.1.2. How to recognize that Pb Free Solder is Used
P.C.Boards marked as “PbF” use Pb Free solder. (See the figure below.)
(Example:Digital board)
Note: The “PbF” marked may be found on different areas of the same P.C.Board,depending on manufacture date.
1.2. AC Caution
For safety, before closing the lower cabinet, please make sure of the following precautions.
1. The earth lead is fixed with the screw.
2. The AC lead is connected properly to power supply unit.
3. Wrap the earth lead around the core 5 times.
4. Wrap the AC lead around the core 5 times.

5
KX-FT931LA-B
1.3. Personal Safety Precautions
1.3.1. Moving Sections of the Unit
Be careful not to let your hair, clothes, fingers, accessories, etc., become caught in any moving sections of the unit.
The moving sections of the unit are the rollers and a gear. There is a separation roller and a document feed roller which are
rotated by the document feed motor. A gear rotates the two rollers. Be careful not to touch them with your hands, especially
when the unit is operating.
1.3.2. Live Electrical Sections
All the electrical sections of the unit supplied with AC power by the AC power cord are live.
Never disassemble the unit for service with the AC power supply plugged in.
CAUTION:
AC voltage is supplied to the primary side of the power supply unit. Therefore, always unplug the AC power cord before disas-
sembling for service.

6
KX-FT931LA-B
1.4. Service Precautions
1.4.1. Precautions to Prevent Damage from Static Electricity
Electrical charges accumulate on a person. For instance, clothes rubbing together can damage electric elements or change
their electrical characteristics. In order to prevent static electricity, touch a metallic part that is grounded to release the static
electricity. Never touch the electrical sections such as the power supply unit, etc.

7
KX-FT931LA-B
2Warning
2.1. About Lead Free Solder (PbF: Pb free)
Note:
In the information below, Pb, the symbol for lead in the periodic table of elements, will refer to standard solder or solder that con-
tains lead.
We will use PbF solder when discussing the lead free solder used in our manufacturing process which is made from Tin, (Sn),
Silver, (Ag), and Copper, (Cu).
This model, and others like it, manufactured using lead free solder will have PbF stamped on the PCB. For service and repair
work we suggest using the same type of solder.
Caution
• PbF solder has a melting point that is 50°~ 70°F, ( 3 0 °~ 40°C) higher than Pb solder. Please use a soldering iron with tempera-
ture control and adjust it to 700°± 20°F, ( 3 70 °± 10°C).
• Exercise care while using higher temperature soldering irons.: Do not heat the PCB for too long time in order to prevent solder
splash or damage to the PCB.
• PbF solder will tend to splash if it is heated much higher than its melting point, approximately 1100°F, ( 6 00 °C).
• When applying PbF solder to double layered boards, please check the component side for excess which may flow onto the
opposite side (See figure, below).
2.2. Insulation Resistance Test
1. Unplug the power cord and short the two prongs of the plug with a jumper wire.
2. Turn on the power switch.
3. Measure the resistance value with an ohmmeter between the jumpered AC plug and each exposed metal cabinet part
(screw heads, control shafts, bottom frame, etc.).
Note: Some exposed parts may be isolated from the chassis by design. These will read infinity.
4. If the measurement is outside the specified limits, there is a possibility of a shock hazard.
2.3. Battery Caution
CAUTION
Danger of explosion if the battery is incorrectly replaced. Replace only with the same or equivalent type recommended by the
manufacturer. Dispose of used batteries according to the manufacturer’s Instructions.
The lithium battery is a critical component (type No. CR2032). Please observe for the proper polarity and the exact location
when replacing it and soldering the replacement lithium battery in.

8
KX-FT931LA-B
3 Specifications
* 1Transmission speed depends upon the contents of the pages, resolution, telephone line conditions and capability of the other
party’s machine.
* 2Transmission speed is based upon the ITU-T No. 1 Test Chart with original mode. If the capability of the other party’s machine is
inferior to your unit, the transmission time may be longer.
* 3If an error occurs during fax reception, such as a paper jam or if the recording paper runs out, the fax and subsequent faxes will
be retained in memory.
Note:
Design and specifications are subject to change without notice.
Applicable Lines: Public Switched Telephone Network
Document Size: Max. 216 mm in width
Max. 600 mm in length
Effective Scanning Width: 208 mm
Recording Paper Size: 216 ×max. 30 m roll
Effective Printing Width: 208 mm
Transmission Time*1:Approx. 15 s/page (Original mode)*2
Scanning Density: Horizontal: 8 pels/mm
Vertical:
3.85 lines/mm - in standard resolution,
7.7 lines/mm - in fine/photo resolution,
15.4 lines/mm - in super fine resolution
Photo resolution: 64-level
Scanner Type: Contact Image Sensor
Printer Type: Thermal printing
Data Compression System: Modified Huffman (MH), Modified READ (MR)
Modem Speed: 9,600 / 7,200 / 4,800 / 2,400 bps; Automatic Fallback
Operating Environment: 5 - 35°C, 20 - 80% RH (Relative Humidity)
Dimensions (H×W×D): Approx. height 121 mm ×width 352 mm ×depth 224 mm
Mass (Weight): Approx. 2.7 kg
Power Consumption: Standby: Approx. 1.2 W
Transmission: Approx. 13 W
Reception: Approx. 30 W (When receiving a 20% black document)
Copy: Approx. 35 W (When copying a 20% black document)
Maximum: Approx. 120 W (When copying a 100% black document)
Power Supply: 120 V AC, 60 Hz
Fax Memory Capacity*3:Approx. 28 pages of memory reception
(Based on the ITU-T No. 1 Test Chart in standard resolution, with original mode.)

9
KX-FT931LA-B
4 General/Introduction
4.1. Optional Accessories
*1 Use only the included or specified recording paper. Using other recording paper may affect print quality and/or
cause excessive wear to the thermal head.
4.2. Translation Lists
4.2.1. Other
4.2.2. Error Message (Report)
Model No. Item Specifications/Usage
KX-A106 Standard thermal recording paper*1216 mm ×30 m roll, with 25 mm core

10
KX-FT931LA-B
4.2.3. Error Message (Display)
5Features
5.1.
General
• LCD (Liquid Crystal Display) readout
Facsimile
• Automatic document feeder (10 sheets)
• Resolution: Standard/Fine/Photo/Super Fine (64 level)
• Broad cast
Integrated Telephone System
• Redialing function
• Phonebook function (100 names)
• Caller ID compatible**
**Feature requires a subscription to caller identification ser-
vices offered by certain local telephone companies for a tee.
You and your caller(s) must be in areas that provide caller
identification services, and compatible equipment must be
used by both telephone companies. Feature not available
when the unit is connected to a PBX system.
Enhanced Copier Function
• 64-Level halftone

11
KX-FT931LA-B
6 Technical Descriptions
6.1. Connection Diagram

12
KX-FT931LA-B
6.2. General Block Diagram
The following is an outline of each device IC on the digital board. (Refer to General Block Diagram (P.13).).
1. ASIC (IC1)
Composed mainly of an address decoder and a modem control.
Controls the general FAX operations.
Controls the operation panel I/F.
Controls the thermal head I/F and CIS I/F.
Performs the image processing.
CPU and Real time clock
Provides the reset pulse for each of the major ICs.
2. Flash ROM (IC2)
Contains all of the program instructions on the unit operations.
This memory is used mainly for the parameter working in the storage area.
3. Dynamic RAM (IC4)
This memory is used mainly for the parameter working in the storage area.
4. MODEM (IC5)
Performs the modulation and the demodulation for FAX communication.
5. Read Section
CIS image sensor to read transmitted documents.
6. Motor Driver (IC7)
Drives the transmission motor and the reception motor.
7. Thermal Head
Contains heat-emitting elements for dot matrix image printing.
8. Sensor Section
Composed of a cover open and film end switch, a document set switch, a document top switch, a paper top sensor and a
motor position switch.
9. Power Supply Board Switching Section
Supplies +6V and +24V to the unit.

13
KX-FT931LA-B
6.2.1. General Block Diagram
POWER SUPPLY BOARD OPERATION PANEL
DIGITAL BOARD ANALOG BOARD
DRAM
4Mbit
3.3V
IC4
FLASH
4Mbit
PROGRAM
3.3V
IC2
FET
ANALOG
SW
IC10
32.256MHz
IC5
MODEM
BOA
R
x
T
x
THERMAL
HEAD
BUFFER
+24V
THON
STB1,2 THLAT,THCLK, THDAT
2 strobe
Tr
CIS
+5V
3.3V chip
LED ON
CLK, SIG
IC7
MOTOR DRIVER
CPU OP-PANEL
I/F
256kbit
ROM
64Kbit
SRAM
A/D IMAGE
PROCESSING
RTC
SERIAL
I/F
MOTOR
I/F
PRINTER
CONTROL
VOL
TONE
32.768KHz
OSC
24MHz
MOTOR
SPEAKER HANDSET
To FLASH
PROGRAMMER
+24
+6V
REG REG
+5V
+6V
+24V+6V
GATE
ARRAY
LCD PANEL
English 2 lines
Tact SW
KEY MATRIX
SENSOR x2
(Doc sensor, Read position sensor)
MESSAGE
MIC
FLASH
4Mbit
(TAM Model)
3.3V
(NC)
IC6 LINERX
CPC
MONRX
LINE
EXT. LINE
Relay
Transformer
LINETX
HOOK
PAPER
(Not Used)
(Not Used)
(Not Used)
BELL
PCONT
ASIC
IC1
TONE1
ACK_EN H/SRX
H/STX_MUTE +24V
RLY
+3.3
RESET

14
KX-FT931LA-B
6.3. Control Section
6.3.1. ASIC (IC1)
This custom IC is used for the general FAX operations.
1. CPU:
This model uses a Z80 equivalent to the CPU operating
at 12 MHz. Most of the peripheral functions are performed
by custom-designed LSIs. Therefore, the CPU only works
for processing the results.
2. RTC:
Real Time Clock
3. DECODER:
Decodes the address.
4. ROM/RAM I/F:
Controls the SELECT signal of ROM or RAM and the
bank switching.
5. CIS I/F:
Controls the document reading.
6. IMAGE DATA RAM:
This memory is programmed into the ASIC and uses 8
KB for the image processing.
7. THERMAL HEAD I/F:
Transmits the recorded data to the thermal head.
8. MOTOR I/F:
Controls the transmission motor which feeds the docu-
ment.
Controls the receiving motor which feeds the recording
paper.
9. OPERATION PANEL I/F:
Serial interface with Operation Panel.
10. I/O PORT:
I/O Port Interface.
11. ANALOGUE UNIT:
Electronic volume for the monitor.
Sends beep tones, etc.
Note*:
This memory is incorporated into the ASIC (IC1) and used for the image processing.
Descriptions of Pin Distribution (IC1)
NO. SIGNAL I/O POWER SUPPLIED
VOLTAGE
DESCRIPTION
1 VSSA GND POWER SOURCE (ANALOG GND)
2 VDDA 3.3 3.3V POWER SOURCE (ANALOG +3.3V)
3 AIN1 A 3.3V CIS IMAGE SIGNAL INPUT (ATN1)
4 AIN2 A 3.3V THERMISTOR TEMPERATURE WATCH INPUT
5 AIN3 A 3.3V LINE VOLTAGE DETECTION SIGNAL INPUT (DCIN)
6 AMON A 3.3V ANALOG SIGNAL MONITOR TERMINAL
7 VSS GND POWER SOURCE (GND)
8 X32OUT O 3.3V/BATT RTC (32.768KHz) CONNECTION
9 X32IN I 3.3V/BATT RTC (32.768KHz) CONNECTION
10 VDD (3.3V / B) ----- POWER SOURCE (+3.3V/LITHIUM BATTERY)
11 XBACEN I 3.3V/BATT BACKUP ENABLE
12 XRAMCS O 3.3V/BATT XRAMCS
13 VDD (3.3V / B) ----- POWER SOURCE(+3.3V / LITHIUM BATTERY)
14 VDD (2.5V/B) ----- POWER SOURCE (+2.5V / LITHIUM BATTERY)
15 FTG O 3.3V SH SIGNAL OUTPUT FOR CIS (FTG)
16 F1 O 3.3V 01 SIGNAL OUTPUT FOR CIS (F1)
17 F2/OP O 3.3V OUTPUT PORT (HEADON)
18 FR/OP O 3.3V OUTPUT PORT (MDMRST)
19 CPC I 3.3V INPUT PORT (CPC)
20 RVN I 3.3V INPUT PORT (PAPER)
21 IRDATXD/IOP I 3.3V INPUT PORT (JAM)
22 IRDARXD/IOP80 O 3.3V OUTPUT PORT (HSTX MUTE)
23 TXD/IOP I 3.3V INPUT PORT (BELL)
24 RXD/IOP I/O 3.3V PORT (TELRXEN)
25 XRTS/IOP I 3.3V INPUT PORT (PSHORT)
26 XCTS/IOP I/O 3.3V PORT (MDMTXEN)
27 VDD (2.5V) ----- POWER SOURCE (+2.5V)
28 TONE1 A 3.3V TONE OUTPUT
29 TONE2 A 3.3V TONE OUTPUT
30 VOLUREF A 3.3V ANALOG REF VOLTAGE
31 VOLUOUT A 3.3V VOLUME OUTPUT
32 VOLUIN A 3.3V VOLUME INPUT
33 XNMI I 3.3V HIGH FIXED
34 FMEMDO/IOP O 3.3V OUTPUT PORT (LED ON)
35 VDD (3.3V) ----- POWER SOURCE (+3.3V)
36 VSS GND POWER SOURCE (GND)
37 VSS GND POWER SOURCE (GND)

15
KX-FT931LA-B
38 VDD (3.3V) ----- POWER SOURCE (+3.3V)
39 MIDAT/IOP I/O 3.3V PORT (TONE1EN)
40 MICLK/IOP O 3.3V OUTPUT PORT (TONE2EN)
41 MILAT/IOP I/O 3.3V PORT (HSRXEN)
42 20KOSC/IOP O 3.3V OUTPUT PORT (PWRCNT)
43 XWAIT I 3.3V INPUT PORT (HOOK)
44 HSTRD/IOP I 3.3V INPUT PORT (TEST)
45 HSTWR/IOP O 3.3V OUTPUT PORT (BLEEDER_ON)
46 XOPRBE O 3.3V OUTPUT PORT (MFCS)
47 ADR15 O 3.3V CPU ADDRESS BUS 15 (NOT USED)
48 ADR14 O 3.3V CPU ADDRESS BUS 14 (NOT USED)
49 ADR13 O 3.3V CPU ADDRESS BUS 13 (NOT USED)
50 VDD (2.5V) ----- POWER SOURCE (+2.5V)
51 XOUT O 3.3V SYSTEM CLOCK (24MHz)
52 XIN I 3.3V SYSTEM CLOCK (24MHz)
53 VSS GND POWER SOURCE (GND)
54 VDD (3.3V) ----- POWER SOURCE (+3.3V)
55 XTEST O 3.3V 24MHz CLOCK
56 TEST1 I 3.3V HIGH FIXED
57 TEST2 I 3.3V HIGH FIXED
58 TEST3 I 3.3V HIGH FIXED
59 TEST4 I 3.3V HIGH FIXED
60 XMDMINT I 3.3V MODEM INTERRUPT
61 XMDMCS O 3.3V MODEM CHIP SELECT
62 XRAS/IOP O 3.3V DRAM ROW ADDRESS STROBE (RAS)
63 XCAS1/IOP O 3.3V DRAM COLUMN ADDRESS STROBE (CAS)
64 XCAS2/IOP I 3.3V PORT (SPMUTE)
65 XRESCS2 O 3.3V FLASH CHIP SELECT (XRESCS2)
66 DB3 I/O 3.3V CPU DATA BUS 3
67 DB2 I/O 3.3V CPU DATA BUS 2
68 DB4 I/O 3.3V CPU DATA BUS 4
69 DB1 I/O 3.3V CPU DATA BUS 1
70 DB5 I/O 3.3V CPU DATA BUS 5
71 VDD (3.3V) ----- POWER SOURCE (+3.3V)
72 VSS GND POWER SOURCE (GND)
73 VSS GND POWER SOURCE (GND)
74 VDD (3.3V) ----- POWER SOURCE (+3.3V)
75 DB0 I/O 3.3V CPU DATA BUS 0
76 DB6 I/O 3.3V CPU DATA BUS 6
77 DB7 I/O 3.3V CPU DATA BUS 7
78 XROMCS O 3.3V FLASH (IC2) CHIP SELECT
79 RD O 3.3V CPU RD
80 WR O 3.3V CPU WR
81 ADR0 O 3.3V CPU ADDRESS BUS 0
82 ADR1 O 3.3V CPU ADDRESS BUS 1
83 ADR2 O 3.3V CPU ADDRESS BUS 2
84 ADR3 O 3.3V CPU ADDRESS BUS 3
85 ADR4 O 3.3V CPU ADDRESS BUS 4
86 ADR5 O 3.3V CPU ADDRESS BUS 5
87 VSS GND POWER SOURCE (GND)
88 VDD (2.5V) ----- POWER SOURCE (+2.5V)
89 ADR6 O 3.3V CPU ADDRESS BUS 6
90 ADR7 O 3.3V CPU ADDRESS BUS 7
91 ADR8 O 3.3V CPU ADDRESS BUS 8
92 ADR9 O 3.3V CPU ADDRESS 9
93 ADR10 O 3.3V CPU ADDRESS 10
94 ADR11 O 3.3V CPU ADDRESS 11
95 ADR12 O 3.3V CPU ADDRESS 12
96 RBA0 O 3.3V ROM/RAM BANK ADDRESS 0
97 RBA1 O 3.3V ROM/RAM BANK ADDRESS 1
98 RBA2 O 3.3V ROM/RAM BANK ADDRESS 2
99 RBA3 O 3.3V ROM/RAM BANK ADDRESS 3
100 RBA4 O 3.3V ROM/RAM BANK ADDRESS 4
101 RBA5 O 3.3V ROM/RAM BANK ADDRESS 5
102 RBA6/IOP96 O 3.3V OUTPUT PORT (NC)
103 STB1 O 3.3V STROBE SIGNAL OUTPUT TO THERMAL HEAD
NO. SIGNAL I/O POWER SUPPLIED
VOLTAGE
DESCRIPTION

16
KX-FT931LA-B
Connection to operation reset circuit
104 STB2 O 3.3V STROBE SIGNAL OUTPUT TO THERMAL HEAD
105 STB3 O 3.3V OUTPUT PORT (NC)
106 XRESET I 3.3V RESET INPUT
107 VDD (3.3V) ----- POWER SOURCE (+3.3V)
108 VSS GND POWER SOURCE (GND)
109 VSS GND POWER SOURCE (GND)
110 VDD (3.3V) ----- POWER SOURCE (+3.3V)
111 XORESET O 3.3V NOT USED
112 VDD(5V) ----- POWER SOURCE (+5V)
113 VSS GND POWER SOURCE (GND)
114 XRESETI I 3.3V RESET INPUT
115 WDERR O 3.3V WATCHED ERROR OUTPUT SIGNAL
116 THDAT O 3.3V RECORDED IMAGE OUTPUT (THDAT)
117 THCLK O 3.3V CLOCK OUTPUT FOR DATA TRANSFER (THCLK)
118 THLAT O 3.3V PULSE OUTPUT FOR DATA LATCH (THLAT)
119 STBNP I 3.3V INPUT PORT (MOT-POS)
120 RM0/IOP O 3.3V MOTOR A PHASE
121 RM1/IOP O 3.3V MOTOR B PHASE
122 RM2/IOP O 3.3V MOTOR /A PHASE
123 RM3/IOP O 3.3V MOTOR /B PHASE
124 RXE/IOP O 3.3V MOTOR ENABLE
125 TMO O 3.3V OUTPUT PORT (NC)
126 VDD (2.5V) ----- POWER SOURCE (+2.5V)
127 VSS GND POWER SOURCE (GND)
128 TM1/IOP O 3.3V OUTPUT PORT (ACK_EN)
129 TM2/IOP O 3.3V OUTPUT PORT (CISON)
130 TM3/IOP O 3.3V OUTPUT PORT (RLY)
131 TXE/IOP I 3.3V INPUT PORT (CUT_POS)
132 KSTART O 3.3V OPERATION PANEL CONTROL
133 KLATCH O 3.3V OPERATION PANEL CONTROL
134 KSCLK O 3.3V OPERATION PANEL CONTROL
135 KTXD O 3.3V OPERATION PANEL CONTROL
136 KRXD I 3.3V OPERATION PANEL CONTROL
137 FMEMCLK/IOP O 3.3V OUTPUT PORT (OPRESET)
138 FMEMDI/IOP O 3.3V OUTPUT PORT (NC)
139 ADSEL1 O 3.3V CHANNEL SELECT SIGNAL FOR AIN2
140 VDDA (2.5V) 2.5V POWER SOURCE (ANALOG +2.5V)
141 VREFB A 3.3V A/D CONVERTER'S ZERO STANDARD VOLTAGE
OUTPUT
142 VCL A 3.3V ANALOG PART STANDARD VOLTAGE SIGNAL
143 VREFT A 3.3V A/D CONVERTER'S FULL SCALE VOLTAGE OUTPUT
144 VSSA GND POWER SOURCE (ANALOG GND)
NO. SIGNAL I/O POWER SUPPLIED
VOLTAGE
DESCRIPTION

17
KX-FT931LA-B
6.3.2. Flash Memory (IC2)
This 512KB ROM (FLASH MEMORY) carries a common area of 32KB and bank areas which each have 8KB (BK4~BK63). The
addresses from 0000H to 7FFFH are for the common area and from 8000H to 9FFFH are for the bank areas.
6.3.3. Dynamic RAM (IC4)
The DRAM serves as CPU and receives memory.
The address is F200H~F3FFH (DRAM access window 1) and F600H~F7FFH (DRAM access window 2).
6.3.4. Reset Circuit (Watch dog timer)
The output signal (reset) from pin 4 of the voltage detect IC (IC3) is input to the ASIC (IC1) 114 pin.
1. During a momentary power interruption, a positive reset pulse of 50~70 msec is generated and the system is reset com-
pletely.
2. The watch dog timer, built-in the ASIC (IC1), is initialized by the CPU about every 1.5 ms.
When a watch dog error occurs, pin 115 of the ASIC (IC1) becomes low level.
The terminal of the 'WDERR' signal is connected to the reset line, so the 'WDERR' signal works as the reset signal.

18
KX-FT931LA-B
6.3.5. RTC Back up Circuit
1. Function
This unit has a lithium battery (BAT1) which works for the Real Time Clock (RTC, Integrated into ASIC:IC1).
The RTC continues functioning, even when the power switch is OFF, backed up by a lithium battery.
2. Circuit Operation
When the power is turned ON, power is supplied to RTC (IC1).
At this time, the voltage at pin 14 of RTC (IC1) is +3.3V. When the power is turned OFF, the battery supplies the power to
RTC through J1, R80, D503. At that time, the voltage at pin 14 of IC1 are about +2.5V. When the power is OFF and the +5V
and +3.3V voltages decrease, the LOW is input to pin 114 of IC1. Pin 111 of IC1 outputs the reset signals. Pin 11 of IC1
become low, then RTC (IC1) go into the back up mode, when the power consumption is lower.

19
KX-FT931LA-B
6.3.6. Supervision Circuit for the Thermal Head Temperature
1. Function
The thermistor changes the resistor according to the temperature and uses the thermistor's characteristics. The output of pin
139 of IC1 becomes a low level. Then when it becomes a high level, it triggers point A. In point C, according to the voltage
output time, the thermal head's temperature is detected.
After the thermal head temperature is converted to voltage in B, it is then changed to digital data in the A/D converter inside
IC1. The CPU decides the strobe width of the thermal head according to this value. Therefore, this circuit can keep the ther-
mal head at an even temperature in order to stabilize the printing density and prevent the head from being overheated.
CROSS REFERENCE:
Thermal Head(P.22)

20
KX-FT931LA-B
6.4. Facsimile Section
6.4.1. Image Dara Flow During Facsimile Operation
Copy (Fine, Super-Fine, Photo)
1. Line information is read by CIS (to be used as the reference white level) via route (1), and is input to IC1. Refer to Block Dia-
gram (P.21)
2. In IC1, the data is adjusted to a suitable level for A/D conversion in the Analog Signal Processing Section, and via route (2) it
is input to A/D conversion (8 bit). After finishing A/D conversion, the data is input to the Image Processing Section via route
(3). Then via route (4) and route (5), it is stored in RAM as shading data.
3. The draft’s information that is read by CIS is input to IC1 via route (1). After it is adjusted to a suitable level for A/D conversion
via route (2), the draft’s information is converted to A/D (8 bit), and it is input to the Image Processing Section. The other side,
the shading data which flows from RAM via route (6) and route (7), is input to the Image Processing Section. After finishing
the draft’s information image processing, white is regarded as “0” and black is regarded as “1”. Then via routes (4) and (5),
they are stored in RAM.
4. The white/black data stored as above via routes (6) and (8) is input to the P/S converter. The white/black data converted to
serial data in the P/S converter is input to the Thermal Head via route (9) and is printed out on recording paper.
Note:
Fine: Reads 3.85 lines/mm
Super Fine: Reads 7.7 lines/mm
Photo: Reads 15.4 lines/mm
Transmission
1. Same processing as Copy items 1 - 3.
2. The data stored in the RAM of IC1 is output from IC1 via routes (6) and (10), and is stored in the system bus.
Via route (11), it is stored in the communication buffer inside DRAM (IC4).
3. While retrieving data stored in the communication buffer synchronous with the modem, the CPU (inside IC1) inputs the data to
the modem along route (12), where it is converted to serial analogue data and forwarded over the telephone lines via the
NCU Section.
Reception
1. The serial analog image data is received over the telephone lines and input to the modem via the NCU section, where it is
demodulated to parallel digital data. Then the CPU (IC1) stores the data in the communication buffer DRAM (IC4) along route
(11).
2. The data stored in DRAM (IC4) is decoded by the CPU (IC1) via route (12), and is stored in RAM via routes (13) and (5).
3. Same processing as Copy item 4.