JVC HC-90 Capacitor Replacement Guide
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Victor's circuit diagrams for the JVC HC-90 and HC-95 print the value of every electrolytic capacitor on the digital main board, the analog main board with its RGB decoder, and the fan motor board: 82 parts in all. They do not cover the power supply, the floppy controller board or the RAM and mapper boards.[1] The HC-95 uses the same boards, so the tables apply to it too.[2]
The values below were read from the restored diagrams. Some labels are small, so check each part on your own board before ordering. The HC-90(B) changed the analog circuit, so a (B), (V) or (T) board may differ from these diagrams.[2] Victor's parts list adds the board number in front of each designator: C573 on the analog board appears as C5573, and C708 on the RGB decoder as C6708.[3]
Power supply
[edit | edit source]No circuit diagram or parts list for the HC-90's power supply has been published, and the values must be read from the parts on your board.[1][4] It is the part that has failed in the reports so far: one HC-95(a) owner brought a dead supply back by replacing its capacitors, and another owner with a dead supply was advised to replace every electrolytic in it.[5][4]
The supply feeds the digital board through CN015: pin 1 +5 V, pin 2 ground, pin 3 +12 V, pin 4 SD, pin 5 −12 V.[1] Record the supply's capacitors before removing any:
| Ref | Capacitance | Voltage | Diameter × height | Notes |
|---|---|---|---|---|
| Mains-side reservoir: check the voltage rating | ||||
Digital main board (EA-1020A / EA-1021A)
[edit | edit source]| Ref | Value | Where on the diagram |
|---|---|---|
| C001 | 4.7 µF 35 V bipolar | Sound mixer round Q001 and Q002, from the YM2149 |
| C002 | 4.7 µF 35 V bipolar | Sound mixer round Q001 and Q002 |
| C004 | 4.7 µF 6.3 V | Sound mixer round Q001 and Q002 |
| C005 | 47 µF 6.3 V | Sound output MIXSND |
| C007 | 4.7 µF 25 V | Sound output SOUND |
| C013 | 47 µF 10 V | Reset circuit (IC002 RST518A and reset switch S001) |
| C015 | 1 µF 50 V | Cassette output, after buffer IC005 |
| C031 | 1000 µF 6.3 V | +5 V input from CN015 |
| C033 | 100 µF 16 V | −12 V input from CN015 |
| C035 | 470 µF 16 V | +12 V input from CN015 |
[1] The 0.1 µF capacitors C101 to C166 across the supply rails are not electrolytic.[1]
Analog main board (EA-5020A)
[edit | edit source]| Value | Positions | Count |
|---|---|---|
| 1 µF 50 V | C560, C575, C576, C577, C632, C633, C634, C635, C681 | 9 |
| 3.3 µF 50 V | C544, C545, C546, C570, C571, C572 | 6 |
| 10 µF 16 V | C586, C587, C628, C630, C631, C658 | 6 |
| 33 µF 16 V | C590, C591, C592, C606, C607, C608 | 6 |
| 47 µF 6.3 V | C579, C580, C582, C583, C584, C585, C588, C626, C643, C647, C651, C685, C686 | 13 |
| 47 µF 16 V | C569, C620, C627, C655 | 4 |
| 100 µF 6.3 V | C531, C533, C578, C596 | 4 |
| 100 µF 10 V | C609 | 1 |
| 220 µF 6.3 V | C573 | 1 |
| 220 µF 16 V | C625, C654 | 2 |
| 470 µF 6.3 V | C540, C593, C594, C595, C636 | 5 |
| 470 µF 16 V | C610 | 1 |
| 1000 µF 10 V | C604 | 1 |
| 1000 µF 16 V | C550, C677 | 2 |
| 2200 µF 6.3 V | C552 | 1 |
[1] C573 was a 0.1 µF ceramic capacitor on early boards and became an electrolytic in a later revision, so an early board may have a ceramic part there.[3] The analog board takes its supplies through CN502: pin 1 +5 V, pin 2 ground, pin 3 +12 V, pin 4 −12 V.[1]
RGB decoder (EA-6020A)
[edit | edit source]| Ref | Value |
|---|---|
| C703 | 1 µF 50 V |
| C705 | 47 µF 6.3 V |
| C708 | 4.7 µF 35 V bipolar |
| C711 | 0.47 µF 50 V |
| C712 | 4.7 µF 25 V |
| C715 | 3.3 µF 50 V |
| C722 | 47 µF 16 V |
| C724 | 47 µF 16 V |
| C725 | 47 µF 16 V |
[1] C708 must be replaced with a bipolar (non-polarised) part. It was changed to a 4.7 µF 35 V bipolar electrolytic in a revision; earlier boards carry a different electrolytic, part QET51HR-105, in that position.[3] No electrolytics are drawn on the analog sub board EA-6021A.[1]
Fan motor board (EA-8020A)
[edit | edit source]C2, 1000 µF 16 V, smooths the +12 V feed to the fan driver.[6]
Which to replace first
[edit | edit source]Forum advice on recapping an MSX is to replace the main supply's capacitors regardless of condition, to judge the audio and video capacitors by the picture and sound, and to replace parts one at a time.[7] On the HC-90 that means:
- The power supply board, recorded first.[5][4]
- The supply input capacitors on the digital board (C031, C033, C035) and the large parts on the analog board (C550, C552, C604, C677).[1]
- The fan board's C2, if the fan runs slowly or not at all.[6]
- The analog and RGB decoder parts, if the picture is poor, and C001 to C007 on the digital board if the sound is weak or distorted.[7]
A higher voltage rating than the original is acceptable where the replacement fits.
Procedure
[edit | edit source]- Unplug the mains lead and leave the computer for several minutes before working near the power supply board.
- Photograph every harness and plug-in board, then remove the boards you are working on. No dismantling procedure has been published.
- Discharge the supply's mains-side capacitor through a suitable resistor and confirm 0 V with a meter. See Capacitor Failure Symptoms for what failed parts look like.
- Replace one capacitor at a time, polarity as marked on the board, and a bipolar part at C001, C002 and C708.[1][7]
- Refit the boards and harnesses as photographed.
After the recap
[edit | edit source]With the mode switch at normal and no cartridge fitted, switch on and measure at CN015 on the digital board: +5 V on pin 1, +12 V on pin 3 and −12 V on pin 5, against pin 2.[1] On the analog board, the diagram gives −2.9 V on pin 33 of the V9938 and 12.0 V supply with an 8.2 V reference on the MC1377P encoder.[1] Remaining faults are covered in the JVC HC-90 Troubleshooting Guide.
Related pages
[edit | edit source]- JVC HC-90
- JVC HC-90 General Maintenance
- JVC HC-90 Troubleshooting Guide
- JVC HC-90 Schematics
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Victor Company of Japan, HC-90/HC-95 circuit diagrams and parts changes, restored by MSXPro. Hosted here as File:Victor HC-90 HC-95 schematics and parts changes.pdf and described on JVC HC-90 Schematics. PDF page 1: analog main board EA-5020A with the RGB decoder EA-6020A and the analog sub board EA-6021A; values printed as capacitance in µF over voltage. PDF pages 2 and 3: digital main board EA-1020A (HC-90, HC-95) and EA-1021A (HC-90(A), HC-95(A)). PDF page 4: fan motor board EA-8020A. There is no power supply circuit.
- ↑ 2.0 2.1 Victor HC-90, MSX Resource Center wiki, 7 March 2026—link(accessed 2026-10-21) Community page: the HC-90 is nearly identical to the HC-95, the only difference being that the HC-90 has one disk drive and the HC-95 two; the HC-90(B) has an updated floppy controller board, analog circuit and power supply.
- ↑ 3.0 3.1 3.2 Victor Company of Japan, HC-90/HC-95 board parts changes, printed pages 10 and 11 (document No. 01129B; PDF pages 5 and 6 of File:Victor HC-90 HC-95 schematics and parts changes.pdf). EA-5020A analog main board: C5573 changed from a ceramic capacitor, QCZ0118-104M, to an electrolytic, QET50JR-227. RGB decoder board: C6708 electrolytic QET51HR-105 deleted and a bipolar electrolytic QEN51VM-475, 4.7 µF 35 V, added. The lists give part numbers and prices, not positions on the board.
- ↑ 4.0 4.1 4.2 Vhd interface for victor hc90/95, July 2022—link(accessed 2026-10-21) Page 8 of 31. leonlas, 2 July 2022: his HC-95A rebooted strangely and showed only 16 KB of RAM; he thought the power supply had died. popolon_, 2 July 2022: replacing every electrolytic capacitor in the power supply should help if the problem is the supply voltages, and the voltages can be measured with the power on; the schematics do not include the power supply. leonlas, 3 July 2022: the supply gives no voltage.
- ↑ 5.0 5.1 The Strange case of a Victor HC-95(a) 512KB!, June 2022—link(accessed 2026-10-21) Page 1 of 5. retrocanada76, 3 June 2022: the power supply of his HC-95(a) was not working, and he reconditioned it, replacing capacitors.
- ↑ 6.0 6.1 File:Victor HC-90 fan motor board EA-8020A schematic.png, from PDF page 4 of File:Victor HC-90 HC-95 schematics and parts changes.pdf: +12 V and ground in from CN016 on board EA-1021A; R1 3.9 Ω; C1 0.1 µF; C2 1000 µF 16 V; zener D1 RD6.8ES(B3); transistors Q1 2SB861(C) and Q2 2SC1685(R,S); output to the fan on CN01.
- ↑ 7.0 7.1 7.2 Recap recommendations, June 2018—link(accessed 2026-10-21) Reply by RetroTechie, 23 June 2018: supply bypass electrolytics round an MSX board can often be removed without the machine stopping; those in the audio and video circuits show their condition in the output; those in the main power supply are worth replacing regardless of condition; compare the parts list with the board where there is one, and replace capacitors one at a time. Other replies recommend Rubycon, Chemi-Con, Nichicon or Panasonic parts from established distributors.
