5550-S/T/V Engineering Changes

Content by "Akamaki". Japanese original HERE.


POST Error Code 162, 163 is Displayed

Replaced the power supply unit (E/C: A27713A) for EC. Implemented in October 1988.

EC Number Model Applicable S/N FBM Replacement Parts
EC341783 5551-S09 9702477-9704090 23F3352 E/C A27713A → A27713B
Power Unit
5551-T09 9732290-9734090
5551-T0A 9762664-9763855
5551-T0B 9790835-9791246


Poor Connection of Speaker Unit

Defects in the assembly process. Implemented in November 1988.

EC Number Model Applicable S/N FBM Replacement Parts
EC341786 5551-S09 -9704005 23F3353 P/N 94X0887
Speaker Assembly
5551-T09 -9734090
5551-T0A -9763837
5551-T0B -9791062
5571-S0A ALL
5571-T0A -9711997
5571-T0B -9732286


Error Code 10483, 10458 on Models with 120 MB Hard Disk

Target HDD (90X9286) S/N C20000001-C20133642. HDD replacement. Implemented in June 1989.

EC Number Model Applicable S/N FBM Replacement Parts
ECC13325 5551-T0B 9790001-9791750 38F7980 P/N 90X9286
120 MB HDD
5551-TRB 9791812-9791814


System Hangs During Mouse Operation Due to Keyboard Controller Errata

Replaced i8742 (P/N 72X8455) on the system board with i8042AH (P/N 90X9052). Implemented in December 1989.

EC Number Model Applicable S/N FBM Replacement Parts
ECC27232 5551-S09 9700001-9719311 57F0083 P/N 72X8455 → 90X9052
Keyboard MPU
5551-T09 9730001-9744587
5551-T0A 9760001-9775698
5551-T0B 9790001-9793081
5551-V0A 97Q0001-97Q1905
5551-V0B 97W0001-97W1228


Dust and Dirt Can Cause Diskette Read Errors

If a 3.5-inch FDD without a shutter is used, replace it with an FDD with a shutter. Implemented in April 1990.

EC Number Model Applicable S/N FBM Replacement Parts
ECC27238 5551-S09 9700001-972412B 56F9013 3.5" FDD
5551-S0A 970000F-973993F
5551-T09 9730001-976849K
5551-T0A 9760001-979162N
5551-T0B 9790001-971088S
5551-V0A 97Q0001-97Q8813
5551-V0B 97W0001-97W2434


Read Error Occurs on Model with 30 MB Hard Disk

Applies to HDD P/N 90X9403, Lot. ~M, ~N. Replaced with HDD (P/N 95F4087). Implemented in May 1990.

EC Number Model Applicable S/N FBM Replacement Parts
ECC72350 5502-S01   79F5411 P/N 90X9403 → 95F4087
30 MB HDD
5502-S11  
5502-T09  
5502-TC9  
5551-S09  
5551-SK9  
5551-SL9  
5551-SC9  
5551-SD9  
5551-T09  
5551-TK9  
5551-TC9  


POST Error Code 602, 10482 on Power on or System Hangs During Use

Applies to system board P/N 23F2146. Replace the delay line module on the system board. Implemented in May 1992.

EC Number Model Applicable S/N FBM Replacement Parts
ECC99401 5551-V0A 97QXXXX-97SXXXX 06G7000 E/C 341631A-341631V
Delay Line Module
5551-V0B 97WXXXX-97YXXXX
5551-V1A 97MAXXX-97NZXXX
5551-V1B 97PAXXX-97PZXXX


Memory Error on Systems with Stage II System Board and Busmaster Adapter Installed

E/C is applicable if the applicable P/N and the memory expansion kit is fully installed (8 MB) on the system board. System board replacement. Implemented in May 1992.

EC Number Model Applicable S/N FBM Replacement Parts
ECC80655 5551-S09 970000A-974177B 79F5493 P/N 38F6769 E/C C12859x
Stage 2 System Board
5551-S0A 970000F-975162F
5551-S19 97AA001-97AL510
5551-S1A 97CA001-97CC180
ECC80656 5551-T09 970000K-978503K 79F5494 P/N 23F3346 E/C C12856x
Stage 2 System Board
5551-T0A 970000N-970571P
5551-T0B 970000S-971348S
5551-T19 97FA001-97FG132
5551-T1A 97HA001-97HF956
5551-T1B 97LA001-97LB875


Read Error Occurs on Model with 30 MB Hard Disk

Replaced ST-506 HDD (P/N 90X9403) with ESDI HDD (P/N 6128287). Also, in the case of Stage I system board, replace the system ROM. Implemented in April 1993.

EC Number Model Applicable S/N FBM Replacement Parts
ECD18009 5502-S01   54G1759 P/N 90X9403 → 6128287
30 MB HDD
System ROM (Stage 1 only)
5502-S11  
5502-T09  
5502-TC9  
5551-S09  
5551-SK9  
5551-SX9  
5551-SU9  
5551-T09  
5551-TK9  
5551-TC9  
5551-TU9  


System Hangs with Busmaster Adapter Installed on Stage I System Board

The corresponding P/N of the system board will be replaced. Implemented in May 1993.

EC Number Model Applicable S/N FBM Replacement Parts
ECD22610 5551-S09 9700001-9719300 64F8690 P/N 94X5577/38F9039 → 56F7422
ECD22611 5551-T09 9740001-9744700 64F8691 P/N 65X1377/94X1572 → 56F7421
ECD22612 5551-T0A 9770001-9775800 64F8692 P/N 94X1572 → 56F7415
Stage 1 System Board
5551-T0B 9790001-9793100


Memory Error on Systems with Stage II System Board and Busmaster Adapter Installed

The corresponding P/N of the system board will be replaced. Implemented in June 1993.

EC Number Model Applicable S/N FBM Replacement Parts
ECD18014 5551-S09 97XXXXA-97XXXXB 54G1624 P/N 38F6769 → 54G1611
Stage 2 System Board
5551-S0A 97XXXXF
5551-S19 97AXXXX
5551-S1A 97CXXXX
ECD18015 5551-T09 97XXXXK 54G1625 P/N 23F3346 → 54G1612
Stage 2 System Board
5551-T0A 97XXXXN-97XXXXP
5551-T0B 97XXXXS
5551-T19 97FXXXX
5551-T1A 97HXXXX
5551-T1B 97LXXXX

Note from Akamaki: I have two early Stage II system boards (P/N 23F3346 E/C C12856x) and a late Stage II system board (P/N 54G1612 E/C D17997), so I compared them and found that the later ones had no jumpers. There were some differences in the addition of 10 wires and the label (model number) of the mounted IC. It seems that the wiring of the board itself has not changed. Stage I seems to have a completely different board size and component layout.

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