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Procedure 4
Connector Check and Replacement Check
The 3.5-inch FDD related wiring diagrams are shown below.
Optional
external
5.25-inch
FDD
The 3.5-inch Floppy Disk Drive is connected to the system unit by the FDD cable. This cable
may be disconnected from the system board or damaged. Disassemble the T4700CS/
T4700CT/T4800CT following the steps described in Chapter 4, Replacement Procedures and
perform the following checks:
Check 1
Make sure the FDD cable is firmly connected to the system board.
If this cable is disconnected, connect it to the lower system board and repeat
Procedure 3. If the FDD is still not functioning properly, perform Check 2.
Check 2
Make sure the two joint connectors (PJ301 and PJ302) are firmly connected to the
upper system board.
If these joint connectors are disconnected, connect them to the upper system
board and repeat Procedure 3. If the FDD is still not functioning properly, per-
form Check 3.
Check 3
The FDD or its cable may be defective or damaged. Replace the FDD with a new
one following the steps in Chapter 4, Replacement Procedures. If the FDD is still
not functioning properly, perform Check 4.
Check 4
The Floppy Disk Controller (FDC) may be defective or damaged. Replace the
lower system board with a new one following the steps in chapter 4, Replacement
Procedures. If the FDD is still not functioning properly, perform Check 5.
Check 5
Replace the upper system board with a new one following the steps in Chapter 4,
Replacement Procedures.
2-24
Lower system board
PJ302
T9901
(FDC)
PJ303
PJ301
PJ304
Internal
5.25-inch
FDD
Upper system board
PJ12
PJ11
Joint connectors
T4700CS, T4700CT, T4800CT
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