Sega Dreamcast Capacitor Replacement Guide

Sega Dreamcast with controller and VMU (photo: Evan-Amos, CC BY-SA 3.0)

The Sega Dreamcast has aluminium electrolytic capacitors on four boards: the logic board, the power supply, the GD-ROM drive's board and sub board 2, the small controller-port board that also holds the clock battery. Each board has its own designators, and the logic board and supply both changed between revisions.

Sega's EU service manual, No. 022-EU, has a full electrical parts list for the European VA1 logic boards and the controller-port board, and that is the source for the VA1 table below. The same manual gives no power supply parts list; Sega's repair centres exchanged the supply whole. The VA0, VA2.1, GD-ROM and power supply lists are console5's, read from boards.

Before recapping

Look for leaking or swollen capacitors and stained pads before replacing anything, and match the fault to a board. dreamcast.wiki reports random reboots once the console has warmed up as a common Dreamcast fault, often caused by poor contact where the power supply connects to the logic board and cured by cleaning and adjusting the pins. Check that connection before recapping the supply. For a drive that will not read discs, dreamcast.wiki gives recalibration, adjustment of the laser potentiometer and new capacitors on the GD-ROM board as the ways such drives are revived. Clean the lens and check the sled first, as the maintenance guide describes. With no power at all, measure 12 V, 5 V and 3.3 V at CN3 pins 1, 5 and 6 before working on the supply.

Designators and part numbers

On the logic board every electrolytic and tantalum capacitor has a CE number; plain C numbers are ceramics. Sega's part numbers tell the two kinds apart: 150- parts are aluminium electrolytics and 153- parts are tantalum chips. On the EU VA1 boards the tantalum positions are CE101, CE102, CE104, CE106 to CE114, CE201, CE203, CE402, CE501 and CE502; Sega's list has no CE105 or CE202. console5's lists leave the tantalums out, and so do the tables here. On the VA0 schematic sheets, CE103, CE302 and CE307 are drawn as tantalum ("TNT") parts, and the connectors sheet has no CE601. Those are the four VA1 electrolytic positions missing from console5's VA0 list.

Logic boards

VA1 logic board, EU 837-13820 and 837-13883 (Sega parts list)

Position	Value	Sega part
CE103	47 µF 16 V	150-0691
CE301, CE302, CE310	10 µF 16 V	150-0688
CE303, CE304	10 µF 10 V, bipolar	150-0696
CE305, CE306	22 µF 6.3 V	150-0690
CE307	100 µF 16 V	150-0728
CE308	47 µF 16 V	150-0691
CE309	4.7 µF 35 V	150-0723
CE401	220 µF 6.3 V	150-0700
CE403	100 µF 6.3 V	150-0687
CE503	47 µF 25 V	150-0699
CE601	47 µF 6.3 V	150-0729

console5's list for the VA1 board 837-13778 gives the same fifteen positions and values. CE303 and CE304 are bipolar; Sega's VA0 schematic marks them "Bipola" and console5 lists them as BP. Fit bipolar parts there.

VA0 logic board (console5)

Position	Value
CE301, CE310	10 µF 16 V
CE303, CE304	10 µF 10 V, bipolar
CE305, CE306	22 µF 6.3 V
CE308	47 µF 16 V
CE309	4.7 µF 35 V
CE401	220 µF 6.3 V
CE403	100 µF 6.3 V
CE503	47 µF 25 V

The VA0 schematic sheets agree with this list at every position except CE309, which they draw as 10 µF 16 V where console5 gives 4.7 µF 35 V. The table follows console5, which read its list from boards. Sega's VA1 schematic also differs from its own parts list at CE309: 4.7 µF 16 V on the drawing, 4.7 µF 35 V in the list. Check the part on the board before ordering.

VA2.1 logic board (console5)

Position	Value
CE103, CE308	47 µF 16 V
CE301, CE302, CE310	10 µF 16 V
CE303, CE304	10 µF 10 V, bipolar
CE305, CE306	22 µF 6.3 V
CE307, CE801, CE802, CE805, CE808	100 µF 16 V
CE309	4.7 µF 35 V
CE401	220 µF 6.3 V
CE403, CE701, CE807	100 µF 6.3 V
CE601, CE803, CE804, CE806	47 µF 6.3 V
CE809	47 µF 25 V

console5 notes that 25 V is acceptable at CE309.

Controller-port board

Sub board 2 carries one electrolytic, CE1, on the 5 V line. Sega lists it as 47 µF 10 V, part 150-0062; console5 lists 47 µF 16 V. A 16 V part fits either. The same board holds the rechargeable clock cell, BT1; see Sega Dreamcast Maintenance Guide before replacing it.

GD-ROM drive boards

GD-ROM boards (console5)

Board	Value	Positions
XU937	47 µF 6.3 V	C2
	100 µF 6.3 V	C3, C10, C14, C17, C61
	100 µF 16 V	C20, C122
XV779 / KS-7S	100 µF 6.3 V	C10, C14, C17, C61, C511
	100 µF 16 V	C20, C509
	47 µF 6.3 V	C127, C203, C205
171-8129A	100 µF 6.3 V	C10, C14, C17, C61, C513, C520
	100 µF 16 V	C20, C509
	47 µF 6.3 V	C127, C203, C205

C510 on the XV779 board is an empty position. Sega's EU parts list gives two GD units, 610-6923-02 (Yamaha) and 610-7292 (Samsung).

Power supplies

Warning: the supply board carries mains voltage, and its bulk capacitor stays charged after the console is unplugged. console5 gives that capacitor as 100 µF 200 V on the 110 V supplies and 47 µF 400 V on the 220–240 V supply. Unplug the console, measure across the bulk capacitor and discharge it through a resistor before working on the board.

Power supply boards (console5)

Board	Value	Positions
171-7874A, -7874A-X1, -7874B (110 V; console5 finds it more often with VA0)	100 µF 200 V	C3
	47 µF 35 V	C10
	1000 µF 25 V	C13
	220 µF 25 V	C16
	2200 µF 10 V	C17, C21
	1500 µF 6.3 V; 470 µF 10 V	C20; C22
171-7874B-X2, 171-7962A, -7962A-X1, 171-7970A, -7970A-X2 (110 V; usually VA1 and VA2.1)	100 µF 200 V	C3
	47 µF 35 V	C10
	470 µF 35 V	C52
	470 µF 16 V	C53
	2200 µF 10 V	C54
	470 µF 10 V	C56
	3300 µF 10 V; 1000 µF 10 V	C58; C59
171-7960A, PWR UNIT PANA EU V01, ETXSE239E2C (220–240 V)	47 µF 400 V	C006
	1800 µF 16 V	C101, C201
	1200 µF 10 V	C103
	470 µF 16 V	C204
	1000 µF 25 V (35 V on some units)	C301, C302

The power supply schematic hosted here, marked "COD. SEGA 837-13570" and listed by console5 among its Tec Toy schematics, uses the same designators as console5's 171-7874A list. It agrees with console5 at C13, C16, C17, C20, C21 and C22, and gives C3 as 68 µF 400 V and C10 as 47 µF 10 V. Where the two differ, fit the higher voltage rating.

Procedure

1. Unplug the console. Remove the modem and the four screws underneath, then lift off the top case (Sega's disassembly steps 2 to 7).
2. Disconnect the power switch connector from the back of the supply, remove its two screws and lift the supply out. Discharge the bulk capacitor before handling the board.
3. To reach the logic board: remove the plate over the drive (Sega's "Sever Plate"), the GD unit (three screws), the flat cable and four screws, the sub board (unplug the fan from CN4 first), the eight screws of the top shield, and the fan. Then lift out the main board.
4. Lift the surface-mount electrolytics with hot air or two irons. Twisting them off can pull pads.
5. Clean any leaked electrolyte from the pads and check under magnification; see Battery Explosion, Capacitor or Corrosion Damage.
6. Fit 105 °C low-ESR parts at the original values, bipolar at CE303 and CE304, observing polarity everywhere else.
7. Reassemble in reverse order and test before closing the case.

Tooling is covered on Recommended Tools, and failure signs on Capacitor Failure Symptoms.

Checks after the recap

The CN3 pin numbers are from the supply schematic. Sega's documents give nominal rail voltages but no tolerances.

Nominal rails

Where	Nominal
Supply header CN3 pin 1	+12 V
CN3 pin 5	+5 V
CN3 pin 6	+3.3 V
IC104 output (SH-4 core)	+1.95 V
IC106 output (HOLLY core)	+2.5 V or +2.7 V, depending on the regulator fitted

Then check that the console reaches the boot screen with no disc, that sound is clean on both channels, that a game disc loads, and that it still runs after twenty minutes.

Related pages

• Sega Dreamcast
• Sega Dreamcast Maintenance Guide
• Sega Dreamcast Troubleshooting Guide
• Sega Dreamcast VA0 Schematics
• Capacitor Failure Symptoms
• Recommended Tools