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Sony HB-55 Capacitor Replacement Guide

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Sony HB-55P inside
HB-55P: the power board with the block capacitors sits on its bracket at the upper left, above the main board (MSX Resource Center wiki photo)

The Sony HB-55P has 33 electrolytic capacitors on its main board and seven on its power board and the 5 V and 12 V regulator boards. Sony's service manual for the HB-55P, HB-75P and HB-75B gives one parts list for both main boards, marking the capacitors fitted to only one model, and its location list places most of them on a coarse grid (rows A to E, columns 1 to 3).[1][2] The tables below list the parts that apply to the HB-55P.

The Japanese HB-55 has a different main board, marked 1-611-737-13, and no parts list for it was found. Read its capacitors from the board.[3]

Where the parts list and the schematic disagree

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The power board schematic and the parts list give different voltage ratings:[1][4]

  • C3: 330 µF 50 V in the list, 330 µF 35 V on the schematic.
  • C4, C6, C7 and C8: 47 µF 25 V in the list, 47 µF 16 V on the schematic.

Fit the higher rating.

Power supply

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HB-55P power supply electrolytics
Ref Board Capacitance Voltage (list / schematic) Sony part no. Position in the circuit
C1 Power 10,000 µF (block) 16 V / 16 V 1-125-375-11 Reservoir after bridge D6, input of the +5 V regulator
C2 Power 3,300 µF (block) 25 V / 25 V 1-125-376-11 Reservoir after D1 and D2, input of the +12 V regulator
C3 Power 330 µF 50 V / 35 V 1-123-362-00 Input of IC3, NJM79L12 (−12 V)
C4 Power 47 µF 25 V / 16 V 1-123-332-00 +5 V output, after L1
C8 Power 47 µF 25 V / 16 V 1-123-332-00 −12 V output
C6 5 V board 47 µF 25 V / 16 V 1-123-332-00 Output of IC1, SI-3052V
C7 12 V board 47 µF 25 V / 16 V 1-123-332-00 Output of IC2, SI-3122V

[1][4] C5, C10 and C11 on these boards are 0.33 µF film capacitors, and C9 on the fuse board is a 4700 pF 400 V ceramic across the power switch.[1]

Main board

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HB-55P main board electrolytics
Ref Capacitance Voltage Sony part no. Grid square
C1 47 µF 25 V 1-123-332-00 B-2
C2 0.47 µF 100 V 1-123-379-00 A-2
C3 47 µF 25 V 1-123-332-00 A-3
C4 470 µF 6.3 V 1-123-298-00 A-3
C5 47 µF 25 V 1-123-332-00 A-3
C6 47 µF 25 V 1-123-332-00 A-3
C7 47 µF 25 V 1-123-332-00 A-3
C10 470 µF 10 V 1-123-310-00 A-2
C19 10 µF 50 V 1-123-356-00 A-2
C22 0.47 µF 100 V 1-123-379-00 A-3
C27 100 µF 10 V 1-123-307-00 A-2
C30 4.7 µF 63 V 1-123-369-00 A-1
C31 22 µF 25 V 1-123-330-00 A-2
C34 47 µF 25 V 1-123-332-00 B-1
C41 4.7 µF 63 V 1-123-369-00 A-2
C42 4.7 µF 63 V 1-123-369-00 A-2
C44 47 µF 25 V 1-123-332-00 B-1
C45 4.7 µF 63 V 1-123-369-00 A-2
C49 47 µF 25 V 1-123-332-00 B-1
C52 4.7 µF 63 V 1-123-369-00 B-1
C54 47 µF 25 V 1-123-332-00 C-2
C55 47 µF 25 V 1-123-332-00 C-2
C57 220 µF 10 V 1-123-308-00 C-2
C59 47 µF 25 V 1-123-332-00 C-2
C60 47 µF 25 V 1-123-332-00 C-2
C61 4.7 µF 63 V 1-123-369-00 C-2
C62 4.7 µF 63 V 1-123-369-00 C-3
C63 4.7 µF 63 V 1-123-369-00 C-3
C64 4.7 µF 63 V 1-123-369-00 C-3
C66 47 µF 25 V 1-123-332-00 E-3
C67 47 µF 25 V 1-123-332-00 E-3
C68 47 µF 25 V 1-123-332-00 E-3
C73 470 µF 6.3 V 1-123-298-00 not in the location list

[1][2] C66 and C67 are marked for the HB-55P only. C8, C9, C14 and C18 (10 µF 50 V) are marked for the HB-75P and HB-75B only and are not fitted to the HB-55P. The parts list prints C16 to C35 with a leading zero (C016 and so on).[1]

Replacement procedure

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Warning: the HB-55 has its mains transformer and fuse inside the case. Unplug the mains cable before opening it.

  1. Open the case and remove the boards as described in General Maintenance. Tape the keytops first; none are locked on the HB-55P.[5]
  2. Photograph each board and note the polarity of every capacitor.
  3. Start with the power board: C1 and C2 are block capacitors, so check the diameter, height and pin spacing of the replacements before ordering. Then C3, C4 and C8, and C6 and C7 on the small regulator boards.
  4. Replace the main board electrolytics, keeping to the same capacitance and at least the voltage in the table.
  5. Refit the boards, reconnect CN10, CN11, CN12 and CN2, and check the rails.

After the recap

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With the machine running, check +5 V, +12 V and −12 V on the power board, and −5 V at pin 1 of one of the 4116-type RAMs.[6] Then check the video adjustments described in General Maintenance if the colour has changed.

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Sony, HB-55P/75P/75B Service Manual (File:Sony HB-55P HB-75P HB-75B Service Manual.pdf), electrical parts list for the main board on page 7-9 (mounted boards A-8050-100-A for the HB-55P and A-8050-098-A for the HB-75P/75B) and for the fuse, LED, power, 5 V and 12 V boards on page 7-14. Hosted with a description at Sony HB-55P, HB-75P and HB-75B Service Manual.
  2. ↑ 2.0 2.1 Sony, HB-55P/75P/75B service manual (File:Sony HB-55P HB-75P HB-75B Service Manual.pdf), main board location list (PDF page 47).
  3. ↑ File:Sony HB-55 (Japanese) main board.jpg, photograph uploaded to the MSX Resource Center wiki by Mars2000you on 3 August 2016: board marked 1-611-737-13.
  4. ↑ 4.0 4.1 Sony, HB-55P/75P/75B service manual (File:Sony HB-55P HB-75P HB-75B Service Manual.pdf), power board schematic, page 5-24: C1 10000 µF 16 V, C2 3300 µF 25 V, C3 330 µF 35 V, C4, C6, C7 and C8 47 µF 16 V.
  5. ↑ Sony, HB-55P/75P/75B service manual (File:Sony HB-55P HB-75P HB-75B Service Manual.pdf), page 2-2: all HB-55P keytops are unlocked; tape the keyboard before removing it.
  6. ↑ Sony, HB-55P/75P/75B service manual (File:Sony HB-55P HB-75P HB-75B Service Manual.pdf), IC supply table beside the main board schematic (PDF page 52): 4116-type RAMs with +12 V on pin 8, +5 V on pin 9, ground on pin 16 and −5 V on pin 1.


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