Jump to content

Sega Saturn (Model 2) Maintenance Guide

From RetroTechCollection
Sega Saturn VA8 main board
A VA8 main board (837-12468). The CR2032 holder BAT1 is at the top right and the controller ports along the bottom edge.

The Sega Saturn Model 2 (HST-3220, MK-80000A, MK-80200A-50) needs the same routine care as the earlier machine: the mains supply, the CD drive, the backup cell and the connectors. Its main boards differ from the first-generation VA0 board that Sega's PAL service manual documents, so the figures below say which board they come from.

Power supply

[edit | edit source]

The Saturn runs from the mains through a power supply inside the case, with a detachable mains lead; the PAL machine is rated AC 220-240 V, 50/60 Hz, about 20 W.[1] Console5 lists supplies by Fujitsu, Panasonic, Phihong, Voltek and Yamaha, each identified by the label on the supply board.[2]

Warning: the primary side of the supply is at mains potential, and its reservoir capacitor (180 V or 200 V rated on 100-120 V supplies, 400 V on 220-240 V supplies) can stay charged after unplugging.[2] Unplug the console, measure across that capacitor and discharge it through a resistor before touching the supply.

Supply rails

[edit | edit source]

On the VA13 schematic the supply connector CN3 has two +5 V pins and two ground pins, and the main board makes the 3.3 V LVCC rail for the SDRAM itself with regulator IC42 (RN5RG33A) and pass transistor TR5 (2SA1213). CE46 (330 µF) sits on the +5 V input and CE47 (10 µF tantalum) on the 3.3 V output; LVCC has a test point, TP62.[3] The two power supply drawings in the same set show a single output with 2700 µF and 1500 µF output capacitors.[4]

The first-generation VA0 board is different: Sega's block diagram shows +9 V, +5 V and +3.3 V all coming from the supply.[5] Neither source gives tolerances.

Disassembly

[edit | edit source]

Sega's procedure for the first-generation PAL machine is six screws for the top case, then the CD compartment lid, the CD drive (two connectors and a flat cable), the shield plate, and the main board.[6] The separate SH-1 board in that procedure is not present on later machines, which carry the CD subsystem on the main board.[7] Note where each screw came from; the lengths differ.[8]

Cleaning

[edit | edit source]
  • Case: a damp microfibre cloth; no abrasives.
  • Controller ports and cartridge slot: isopropyl alcohol on a swab or soft brush, left to dry before power is applied.
  • Vents and boards: dry air or an anti-static brush.
  • Lens: a cotton swab barely damp with isopropyl alcohol, left to dry before the lid is closed.

Capacitors

[edit | edit source]

Later main boards use through-hole electrolytics. Lists by board revision are on the Sega Saturn (Model 2) Capacitor Replacement Guide; the power supply and CD-ROM board lists are on the Sega Saturn (Model 1) Capacitor Replacement Guide.[2] CE45 and CE46 swap values between revisions: from VA6 onwards CE45 is 220 µF and CE46 330 µF, the other way round from the VA1, VA SG and VA SD boards.[2] See Capacitor Failure Symptoms and Battery Explosion, Capacitor or Corrosion Damage.

CD drive

[edit | edit source]

Console5 lists CD-ROM boards from JVC (EXL-P604, EXL-P605, ENR-007 B/D), Hitachi (JA00292) and Sanyo (CDK94V5SGC).[2] Sega's published procedure is for the drive unit in the first-generation PAL machine (610-5679-20/-21):[9]

  • The RF level at the RF test point, with a disc playing, should be 0.8 to 1.4 Vp-p. Below 0.8 Vp-p the pickup is worn and should be replaced.
  • The variable resistor on the pickup's APC board is set at the factory and must not be adjusted; Sega warns that turning it may damage the laser diode.
  • The servo adjustments (FE bias, focus gain, FE balance, tracking gain) need an oscilloscope and a test disc and interact with each other. The full procedure is on the Sega Saturn (Model 1) Maintenance Guide.
  • When the beam has to be checked, observe from more than 30 cm from the objective lens.

Clean the lens before measuring anything.

Backup battery

[edit | edit source]

The backup RAM and clock run from a CR2032 cell.[8] On the VA8 board it sits in holder BAT1 near the top right corner. If saves are lost and the console asks for the date and time at every start, replace the cell with the console unplugged and check the holder for corrosion. See Battery Refurbishment.

Connectors

[edit | edit source]
  • The A/V OUT connector: the picture should not change when the lead is moved.
  • The controller ports. Console5's note on voltage drops at the ports with higher-current peripherals applies to the VA0 to VA0.8 boards; it says later revisions deleted the port fuse and the ground ferrite beads.[2]
  • The cartridge slot, used for memory and RAM cartridges.
  • The flat cable between the CD drive and the main board.
  • The mains inlet and the power switch.

Clean with isopropyl alcohol and reseat; reflow cracked joints.

Cooling

[edit | edit source]

The Saturn has no fan and is cooled through vents in the sides and base; keep them clear.[7] Sega's operating range is 5 to 35 °C at 10 to 80% RH, non-condensing.[1]

Maintenance checklist

[edit | edit source]
  1. Check +5 V at the supply connector and 3.3 V at the main board after storage.
  2. Clean the cartridge slot, controller ports and AV connector.
  3. Replace the CR2032 when saves are lost.
  4. Inspect the supply and main board capacitors for leakage or bulging.
  5. When discs stop reading, clean the lens before suspecting the pickup.
  6. Keep the vents clear.
[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 Sega Enterprises, Service Manual: Sega Saturn (PAL), No. 013-1, June 1995, section 1 "Specifications" (p. 3). Written for the first-generation PAL machine. See Sega Service Manual - Sega Saturn Pal - 1 June 1995.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Console5 TechWiki, "Saturn" (secondary source): capacitor lists for main boards VA0 to VA15, power supplies by maker and model, and CD-ROM boards.
  3. ↑ Conjunto P.C.I. VA-13 (Saturn VA13 schematic set, scanned by Brasilmodchip), main schematic diagram sheet 10/11 (PDF p. 11). See Sega Saturn VA13 Service Manual (PAL).
  4. ↑ Conjunto P.C.I. VA-13 scan, PDF pp. 14-15: Brasilmodchip drawings "Fonte Full Range" and "Fonte Saturn KS14B". See Sega Saturn VA13 Service Manual (PAL).
  5. ↑ Sega Enterprises, Service Manual: Sega Saturn (PAL), No. 013-1, June 1995, section 7 "Block diagram" (pp. 11-12). See Sega Service Manual - Sega Saturn Pal - 1 June 1995.
  6. ↑ Sega Enterprises, Service Manual: Sega Saturn (PAL), No. 013-1, June 1995, section 5 "Disassembly procedure" (pp. 6-7). See Sega Service Manual - Sega Saturn Pal - 1 June 1995.
  7. ↑ 7.0 7.1 Japanese Wikipedia, "セガサターン" (secondary source), section "バリエーション": the HST-3210 moved the CD subsystem onto the main board; the HST-3220 is the Model 2; the console has no cooling fan.
  8. ↑ 8.0 8.1 Sega Enterprises, Service Manual: Sega Saturn (PAL), No. 013-1, June 1995, section 11 "Exploded view and parts list" (pp. 70-77). See Sega Service Manual - Sega Saturn Pal - 1 June 1995.
  9. ↑ Sega Enterprises, Service Manual: Sega Saturn (PAL), No. 013-1, June 1995, "Protection of eyes from laser beam during servicing" (p. 2) and section 6 "CD drive maintenance and adjustment" (pp. 8-10). See Sega Service Manual - Sega Saturn Pal - 1 June 1995.
Retrieved from "https://retrotechwiki.com/index.php?title=Sega_Saturn_(Model_2)_Maintenance_Guide&oldid=17527"