Toshiba T4400SXC User manual

1.1 General
The Toshiba T4400SXC Personal Computer uses extensive Large Scale Integration (LSI), and
Complementary
Meta1~Oxide Semiconductor (CMOS) technology to provide minimum size
and weight, low power usage and high reliability. The T4400SXC incorporates the following
features and benefits:
o ~croprocessor
TheT4400SXC uses an 80486SX-25 microprocessor that operates at 25 MHz.
o Math co-processor
TheT4400SXC comes with a built-in socket for an 80486DX-25 which has a
Numeric DataProcessing Unit (NDP).
o Cache memory
The T4400SXC has an 8 KB cache memory which is stored in the 80486SX
microprocessor.
o Disk storage
TheT4400SXC has an internal 80 or 120 Megabyte (MB) Hard DiskDrive
(HDD) with an average access time
of 19 milliseconds. A 3.5-inchFloppy Disk
Drive (FDD) supports 2HD floppy disks (1.44 Mbytes) and 2DD floppy disks
(720 Kbytes).
o Memory
TheT4400SXC comes standard with 4 MB
of CMOS Random Access Memory
(RAM). This includes 640 KB
of conventional memory and 3,456 KB of
extended memory which can be utilized as expanded memory compatible with
the Lotus/lntel/Microsoft Expanded Memory Specifications (LIM-EMS).
o TFf color LCD
A high resolution Liquid Crystal Display (LCD) 640x480 pixels 512 colors for
both graphics and characters.
The T4400SXC internal display controller supports Video Graphics Adapter
(VGA) functions on the internal display devices.
o Keyboard
An easy to use 82/84-key keyboard with full-size keys and standard spacing is
compatible with IBM standard software.
(] Batteries
The T4400SXC has three different batteries: a main battery, a backup battery,
and a Real Time Clock (RTC) battery.
o Expansion port
TheT4400SXC has one unique 150-pin expansion port.
o Parallel port
A centronics compatible parallel interface port serves two purposes. The port
can be used to connect a centronics compatible printer or an external floppy disk
drive.
(] RS-232-C port
The T4400SXC has one 9-pin serial interface port.
1-5

1-6
o Tenkey port
The T4400SXC has a tenkey pad interface connector on the left side that can be
connected to an external tenkey pad.
o Mouse port.
The T4400SXC has one 6-pin mouse port on the back that can be connected to
an
mM PS/2 mouse.
o RGB port
The T4400SXC has one I5-pin ROB port on the back that can be connected to an
external video display.

The T4400SXC Personal Computer is shown in figure 1-1. Its system configuration is shown
in figure 1-2.
Battery pack
Figure 1-1 T4400SXC system unit
PJ27 PJ19
PJ4
PJ5
PJ17
PJ18 PJ14 PJ9
Built-in modem
RS-232-C
PJ7 PJ25
PJ13
I--!--....I
PJ12I--+---I
PJ21----I Sub battery
PJ1 ~--I RTC battery
PJ3
Figure 1-2 System unit configuration
1-7

.....
Co
"-':I
ciQ'
c
~ ~
I
(M
t=
~
~
Co
;'
(JQ
r3
S
...--
LA23·17
----------~~~----------------------::::============:::::::::::g~~.1~7::~
SA19·0
SAUI·O
SOls.o
OSC
(20M)
CLKGEN
SOls.o
l.J
l
~=~-""l~
25M
44.9M
~
EXP
,
24M
28.322M
-=-,5:.0
A1'.M..5.
HOD
I/F
--
HOD
;
14.745M
25.175M
Dul
14.318M
l---'"
FY4H01
32.768K
RTC
BACK
UP
BATTERY
PVGA1
F
~
-.J
RAMV-
1:1->-=--
__
----1
PS/2
MOUSE
1r:i)8~~
KBC
-IEiIl TENKEY
RAMV-~
LJ
D
RAMV-~
:::>
80PIN
KB
L..-
___
----I
GA
~
I
ED
t----mIiD PANEL ONIOFF
SYS-
LA23·17
FY4LE2
CONT
FDD
CPU
A23.2
344PIN
SI
SERIAL
80486SXI
S015.0
'=>
T9901'1 P PRT/FDD
(EXP)
80486DXf-.-.,Q,31~
L
20BPIN
(*1) :
DMA
x 2
(25MHz)/
PIC
x 2
P23T
SA19.0
~
PIT
x 1
r-
-
SIOx2
~s
SPEAKER
FDC
x 1
L...-
__
..... I
VFO
x 1
-B-I-O-S-
....
I(
S015-O
~
~~KUP
ROM
L---I
r----
32K
x B
12BKxB V
SA19-O
1.
r
~
.....
RAMV
II
~
+5V
(VCC)
............
-S-Y-S--...,L----J
uBUILT-INMOOEM
I
~
~5V
(RAMV)
+--OCIN
r
RAM
~
~TYPEE
.
-<~
~12V
+--MAINBATTER'
512KxB
L.
RAMV
T E
+--BACKUPBAn
MEMORY
JiJV
~
(DRAM
CARD)
t;
PS
031-0
~
-'
~~~1~
~r=S=P=V===-
__
.J
:!1
I-l
(1Q
N
a
....
I
Vl
1-3
~.
:r'
V)
~
nl
a-
00
-
~
g
~
-
~
nl
&.
9
~
~
~
a =
....
-
0 =
......
...
-
::r 0
0
t")
t
~
~
8
_.
D)
en
(fQ
><
..,
(") D)
V)
9
'<
V)
...
0
3
c:
~.

The T4400SXC system board shown in figure 1-3 is composed of the following major
components:
o An 80486SX-25 CPU
o Super Integration (SI) T9901, which stores the following components:
• Two Direct Memory Access Controller (DMAC):
• Two Programmable Interrupt Controller (PIC):
• One Programmable Interval Timer (PIT):
• One Floppy Disk Controller (FDC):
• One Serial Input/Output controller (SIO):
• One Variable Frequency Oscillator (VFO):
• One I/O Controller
o A Real Time Clock (RTC): 146818AF
o A KeyBoard Controller (KBC): M37452M4
o A Power Supply Controller (PSC): 47C660
o The following memories:
Standard RAM: 4MB
82C37
82C59
82C54
TC8565
TC8570
TC8568
Cash memory 8 KB (inside CPU)
Backup RAM:
32KB
BIOS ROM: 128 KB (96 KB are used)
This ROM contains Initial Reliability Test (IRT), Basic
Input/Output System (BIOS), and video BIOS.
Video RAM: 256KB
Optional memory cards expand memory to a maximum of 20 MB.
o System control gate array :
o VGA display controller:
SYS CNT-GA (344-pin)
PVGA1F: WD90C30 (132-pin)
o The following Oscillators (OSC):
• 24 MHz OSC
(Xl) is used for the FDC and VFO.
• 25.0 MHz OSC (X2) is used for the CPU.
• 14.7456 MHz OSC (X6) is used for the COM.
• 14.31818 MHz OSC (X7) is used for the KBC.
• 32.768 KHz OSC (X8) is used for the RTC.
1-9

1.3 The T4400SXC 3.S-inch Floppy Disk Drive
"'-.<- .... ~~~~_,_.~Tht- .. I-4400SX..c~3._'\:.iJlr.]3,F.JappyDiskDrivJ" ... f:FDn~js...a..tbin_bie.h-!1""rlOl1Jlan~ereli~hl~prjllf",_=-=-=c--_-----=--:------c=:-~~.",- .... ·
that supports 720-KB (fonnatted) 2DD and 1.44-MB (fonnatted) 3.5-inch floppy disk.
The T4400SXC FDD is shown in Figure 1-4. The specifications for the FDD are described in
Table 1-1.
Figure 1-4 3.5-inch FDD
Table 1-1 3.5-inch FDD specifications
Item 2·MB mode 1-MB mode
Storage capacity (KB)
Unformatted 2,000 1,000
Formatted 1,475 737
Number of heads 2 2
Number of cylinders 80 80
Access time (ms)
Track
to track 3 3
Average 94 94
Head settling time 15 15
Recording track density (tpi) 135
135
Data transfer rate (Kbps) 500
250
Rotation speed (rpm) 300 300
Recording method Modified Frequency Modulation (MFM)
1-10

1.4 The T4400SXC 2.S-inch Hard Disk Drive
The T4400SXC's 80-MB or 120-MB (formatted) Hard Disk Drive (HDD) is a random access
non-volatile storage device.
It has a non-removable 2.5-inch magnetic disk and mini-
winchester type magnetic heads.
The T4400SXC HDD is shown in Figure 1-5. Specifications for the HDD are described in
Table 1-2.
Figure I-S 2.S-inch HDD
Table 1-2 2.S-inch HDD specifications
80 MB (CP-2084) 120
MB (CP-2124) 120 MB (MK2124FC)
Storage capacity (MB)
Formatted 85.4 121.6 130.1
Number of disks 2 2 2
Data heads 4 4 4
Data surfaces 4 4 4
Track per surface 1,097 1,123 1,155
Sectors per track 38 (+1) 53 (+1) 55 (+1)
Bytes per sector 512 512 512
Access time (ms)
Track to track 5 3 5
Average 19 16 17
Maximum 40 40 36
Rotation speed (rpm) 3,486 3,486 3,200
Data transfer rate (bps)
Tolfrom media
1.5M 2.2M 6.5M
Interleave
1:1 1:1 1:1
Recording method 2-7 RLU1-7 RLL 2-7 RLU1-7 RLL 1-7 RLL
1-11

1.5 The Keyboard
The 82-(USA) or 84-(European) keyboard is mounted on the T4400SXC's system unit The
keyboard is connected to the keyboard controller on the system board through 19-pin flat
cables. The keyboard is shown in Figure 1-6.
See Appendix E for optional keyboard configurations.
Figure 1-6 Keyboard
1-12

1.6 TFT Color LCD Display
The TFf Liquid Crystal Display (LCD) contains an LCD module, a Fluorescent Lamp (FL),
and FL inverter board.
1.6.1 LCD Module
The T4400SXC TFf color LCD is illuminated from the side and supports 640x480 pixels
with High Resolution Graphics Subsystem (HRGS) and 512 colors for graphics and
charactors. This HRGS includes the functions
of Video Graphics Array (VGA).
The LCD receives vertical and horizontal synchronizing signals, 8-bit data signals (4-bit
upper data signal, 4-bit lower data signal), and shift clock for data transmission. All signals
are CMOS-level compatible.
The
TFf LCD is shown in Figure 1-7. The specifications for the LCD are described in Table
1-3.
Figure 1-7 TFT LCD
Table
1-3 TIT LCD specifications
Item Specifications
Number of dots (dots) 640x480
Dot pitch (mm) 0.27(W)xO.27(H)
Display area (mm) 171(W)x13O(H)
Contrast 60:1 (typ.)
FL current (mA) 4.5 to 5.5
FL frequency (KHz) 20 to 60
1-13

1.6.2 Fluorescent Inverter Board
The FL inverter board supplies high frequency current to light the LCD's Fluorescent Lamp
The specifications for the
FL inverter are described in Table 1-4.
Table 1-4 FL inverterspecifications
Item
Specifications
Input Voltage (V) 18
Power (W) 5.6
Output Voltage (V) 1100 (rrns) (Max.)
Current (rnA) 5.0x2
Frequency (KHz)
4.7
Bounds of current (rnA) 2.8 to 5.0
1-14

1. 7 Power Supply Board
The power supply board supplies five voltages to the T4400SXC system board. The T4400SXC
power supply board has one microprocessor and it operates at 500 KHz.
It contains the following functions:
1. Determines if the AC adapter or battery is connected to the computer.
2. Detects DC output and circuit malfunctions.
3. Controls the LED indicator panel and speaker.
4. Turns the battery charging system on and
off and detects a fully charged battery.
5. Determines
if the powercan be turned on and off.
6. Provides more accurate detection of a low battery.
7. Calculates the remaining battery capacity.
The power supply board is shown in figure 1-8 and the output rating is specified in table 1-5.
Figure 1-8 Power supply board
Table
1-5 Power supply board output rating
DC Regulation Maximum
Items
voltage
tolerance current
(V) (%) (mA)
System logic, FOO, HOC, HOD (VCC) +5 ±5 3,500
Backup RAM
(VRAM) +4.7 ±5 440
RS-232-C
(VOO)
+12 ±5
15
RS-232-C, Modem (VEE) -9 ±10 15
TFT LCD (OSPV) +12 to +18.9 860
1-15

1-16

2.1 T4400SXC Troubleshooting
Pan 2 describes how to determine if a Field Replaceable Unit (FRU) in the T44QOSXC is
causing the computer to malfunction.
The FRUs covered are:
1. Power supply board
2. System board
3. Floppy
Disk Drive
4. Hard DiskDrive
5. Keyboard
6. Display
The following tools are required to perform the T4400SXC troubleshooting steps.
1. A T4400SXC Diagnostics Disk
2. A Phillips head screwdriver (2 mm)
3. An MS-DOS system disk
4. An 2DD
or 2HD formatted work disk for floppy disk drive testing
5. A Cleaning disk kit for the floppy disk drive troubleshooting
6. A Printer port LED
7. An RS-232-C wraparound connector
8. A Printer wraparound connector
9. A Multimeter
10. External RGB monitor
11. External 5-1/4" floppy disk drive
2-5

2.2 Troubleshooting Flowchart
Use the flowchart in figure 2-1 as a guide to detennine which FRU testing procedures to
execute. Before perfonning the flowchart steps, make sure all optional equipment is
disconnected from the computer and the floppy disk drive is empty.
2-6
NOTE: Ifyou/orget the passwordand cannot start up the computer, connect the
printerportwraparound board (F31PRT), then turn the POWER switch on. The
computer will skip the password/unction.
Turn the POWER switch on.
Wait 5 seconds or more.
Perform the Power
Supply
~":"::=+I Troubleshooting Steps
in section 2.3.
Perform the System Board
=::::"':"';-+1 Troubleshooting Steps
in section 2.4.
Perform the Display
----. Troubleshooting Steps
in section 2.8.
Perform the System Board
-----"-"""--' Troubleshooting Steps
in section 2.4.
If the "Password=" message displays,
type the password, then press ENTER.
To by·pass the password function, insen
the password service disk and
ress ENTER.
Perform the Hard Disk Drive
Troubleshooting Steps
in section 2.6.
Perform the Keyboard
~>'-'-::,.j Troubleshooting Steps
in section 2.7.
Figure 2-1 Troubleshooting flowchart (1/2)

Insert the diagnostics disk into
the FDD, then type
A> TESTCE44
and ress ENTER.
Perform each test.
System is normal.
Perform the Floppy Disk
~-~ Drive Troubleshooting Steps
in section 2.5.
After confirming which
Yes diagnostic test detected
an
error, perform the relevant
problem isolation procedures
outlined below.
Figure 2-1 Troubleshooting flowchart (2/2)
If the diagnostics program does not detect any errors, the problem may be an intermittent one.
Execute the running test program several times to isolate the problem.
After confirming which diagnostic test detected an error, perform the appropriate
troubleshooting steps below:
1. If an error is detected on the system test, memory test, display test, ASYNC test,
printer test, or real timer test, perform the system board troubleshooting steps in
section 2.4.
2. If an error is detected on the keyboard test, perform the keyboard troubleshooting
steps in section 2.7.
3. If an error is detected on the floppy disk test, perform the floppy disk drive
troubleshooting steps in section 2.5.
4.
If an error is detected on the hard disk test, perform the hard disk drive
troubleshooting steps in section 2.6.
2-7

2.3 Power Supply Board Troubleshooting Steps
TheT4400SXC's power supply board controls many functions and components in the
T4400SXC. To determine if the power supply board is functioning properly, perform the
following checks as required. Start with step 1 and continue with the other steps
if you need
to.
Step
1:
Battery Indicator Checklist
Step
2:
Power Supply Board Connector Checklist
Step
3:
System Board and Power Supply Board Replacement Checklist
Step 1 Battery Indicator Checklist
The T4400SXC's AC adapter convens AC power to DC and contains a charging circuit
which charges T4400SXC's batteries. The adapter connects to the DC IN
21 V connectoron
the back
of the computer. When the AC adapter is connected and the T4400SXC poweris
off, the AC adapter charges the T4400SXC's batteries.
The battery indicator displays the status
of the battery pack's charge and whether or not the
AC adapter is connected and suppling power. The indicator labeled
"Battery" glows amber
when the AC adapter is charging the T4400SXC's battery pack.
The indicator labeled "Battery"lights red
if power is supplied from the AC adapter when
you connect the AC adapter to the T4400SXC and a wall outlet.
If the AC adapter's output
voltage is abnormal
or the power supply malfunctions, this indicator blinks red or does not
glow.
(1) If the battery indicator blinks red, see check 1.
(2) If the battery indicator blinks yellow, see check 2.
(3)
If the battery indicator does not glow, see check 3.
Check 1 When tum on the power and battery indicator blinks once on a time on battery
operation, main battery will be fully discharged. Charge the main battery, then try
again.
2-8
When the battery indicator informs the repeatedly blinking, AC adapter, power
supply board,
or battery will be damaged. The repeatedly blinking is an error
status
of power supply.
The battery indicator repeatedly informs the 4-bit status that is varied the blinking
interval with change
of problem.
The battery indicator is put out two seconds at first, and
it lights one or a half
second with an interval
of a halfsecond in tum from bit 0 to bit 3. If the battery
indicator glows 1 second, it shows the
"1." If the battery indicator glows 0.5
second, it shows the "0."

The following timing chart shows the example, that the status is 5h (0101). Read
the timing chart f
rom right to left.
ON
Battey OFF
BilO
,
Bil'
o
Bk2
,
Bk3
o
25 15 O.Ss 0.55 0.55 15 O.Ss 0.55
---i~~ Time
• Reading
The status and its meaning are described in table 2-1.
However, when
the battery indicator blinks at random, the AC adapter or charging
circuit may be damaged. In this case, replace the
AC adapter with a new one. If
the problem still exists, perform PROCEDURE 3.
Check 2 When the main battery temperature is abnormal, battery indicator blinks yellow,
and the system cannot charge the main battery.
Check 3
Make sure the AC adapter's cable and AC cord are fIrmly plugged into the DC IN
21 V socket and wall outlet. If these cables are plugged correctly, go to
PROCEDURE 2.
2-9

Step 2 Power Supply Board Connector Checklist
____________ _ ____ The. JlID'lecSllppJ}'-.iIDarcLis. con nec.te.dJo .the- syste.m.boaro.by.one. fleyibk...cab1e-.- -Thiscable -- - -- --- -- --,-- ------,,--.~.-=--=-=-~--=--- -
connector can become disconnected from the power supply board causing the T4400SXC to
malfunction.
To check these connections, it is necessary to disassemble the T4400SXC.
Refer to part 4, Replacing T4400SXC Field Replaceable Units for more information about
how to disassemble the T4400SXC.
When the T4400SXC is disassembled, make sure the following connections are secure and
the cables are not disconnected, pinched
or broken. Replace any broken or damaged
connectors with new ones, connect any disconnected cables and assemble the T4400SXC.
Execute the same procedures that were causing the T4400SXC to malfunction. If the
computeris still not functioning properly, go to step 3.
Check 1 The following cable connections connect the power supply board to the system
board.
Power supply board PJ26
I System board
PJ4 PJ27
Step 3 System Board and Power Supply Board Replacement Checklist
The power supply board is connected to the system board. Power is supplied to the power
supply board from the
DC IN plug. The power supply board or the system board may be
damaged. Replace the power supply board and system board as instructed in checks 1 and 2
below. The procedures for replacing the power supply board and system board are described
in part 4, Replacing T4400SXC Field Replaceable Units.
Check 1 Replace the power supply board with a new one and restart the system. If the
T4400SXC does not function properly, perform check 2.
Check 2 Replace the system board with a new one. If the T4400SXC still does not function
properly, other FRUs may be damaged. Perform the T4400SXC's Diagnostics
Test to locate the malfunctioning FRU(s).
2-10

2.4 System Board Troubleshooting Steps
To determine if the system board is defective or not functioning properly, perform the
following set
of steps beginning with step 1 and continue with the other steps as required.
Step 1:
Message Checklist
Step 2:
Printer Port LED Checklist
Step 3: Diagnostic Test Program Execution Checklist
Step 4: LED Board and RTC Battery Checklist
Step 5: System Board Replacement Checklist
Step 1 Message Checklist
1. Turn on the T4400SXC's power.
2. If the system is loaded normally, go to step 3.
3.
If any of the following messages are displayed on the screen, press the Fl key to ex-
ecute the SETUP program. Refer to part 3, Test andDiagnostics for more information
about the T4400SXC's SETUP program.
**** Error
in CMOS. Bad battery ****
Check system. Then
press
[Fl]
key
**** Error
in CMOS.
Bad check sum
****
Check system. Then
press
[Fl]
key
****
Error in CMOS. Bad configuration ****
Check system. Then press
[Fl]
key
·.
**** Error in
CMOS. Bad memory size
****
Check system.
Then press
[Fl]
key
·.
****
Error in CMOS. Bad HDD type ****
Check
system. Then
press
[Fl]
key
·.
**** Error
in CMOS.
Bad time
function ****
Check system.
Then press
[Fl]
key
·.
2-11

4. Ifthe following message is displayed on the screen, tum offthe power. Wait five
seconds or more, and tum on the power again. If
the same message reappears, go to
section 2.6, Hard Disk Drive Troubleshooting Steps.
Insert system disk in drive
Press any key when ready .....
5. If any of the following messages are displayed on the screen, go to step 4.
CPU ERROR
SYSTEM ROM CHECK SUM ERROR
TIMER CH.2 OUT ERROR
PIT ERROR
MEMORY REFRESH ERROR
FIRST 64KB MEMORY ERROR
RTC ERROR
CRTC ERROR
VRAM ERROR
KBC ERROR
SYSTEM MEMORY ERROR
SYSTEM MEMORY PARITY ERROR
PROTECTED MODE ERROR
CPU EXCEPTION ERROR
EXTENDED MEMORY ERROR
EXTENDED MEMORY PARITY ERROR
EMS PAGE REGISTER ERROR
EXPANDED MEMORY ERROR
EXPANDED MEMORY PARITY ERROR
DMA PAGE REGISTER ERROR
DMAC #1 ERROR
DMAC #2 ERROR
PIC #1 ERROR
PIC M#2 ERROR
KEYBOARD ERROR
KBC ERROR
HDC ERROR
HDD #0 ERROR
HDD #1 ERROR
NO FDD ERROR
FDC ERROR
TIMER INTERRUPT ERROR
RTC UPDATE ERROR
6. If none of these messages are displayed and you have a printer port LED, go to step 2.
2-12