Sega CD (Model 2): Difference between revisions
No edit summary |
|||
| (2 intermediate revisions by the same user not shown) | |||
| Line 29: | Line 29: | ||
Launched '''April 1993''' in Japan and late-1993 overseas, it re-engineers the bulky front-loading Model 1 into a '''smaller, top-loading deck''' that bolts to the right-hand side of a Model-2 Genesis (or underneath a Model-1 via spacer plate). The redesign slashes build cost by integrating disc-logic, FM synth mix, and RF modulator into two new ASICs and by replacing the complex motorised tray with a spring-latched lid. | Launched '''April 1993''' in Japan and late-1993 overseas, it re-engineers the bulky front-loading Model 1 into a '''smaller, top-loading deck''' that bolts to the right-hand side of a Model-2 Genesis (or underneath a Model-1 via spacer plate). The redesign slashes build cost by integrating disc-logic, FM synth mix, and RF modulator into two new ASICs and by replacing the complex motorised tray with a spring-latched lid. | ||
== | == Historical Context & Sales == | ||
* Sega’s first CD drive – the '''Model 1 “front-loader”''' (HAA-2910) – cost US$299 and carried a high RMA rate (optical alignment, belt stretch). | * Sega’s first CD drive – the '''Model 1 “front-loader”''' (HAA-2910) – cost US$299 and carried a high RMA rate (optical alignment, belt stretch). | ||
* Cost-reduction taskforce (“MCD-R2”) produced a simplified mechanism using Sony’s ubiquitous '''KSS-210A''' pickup and a plastic clam-shell housing. | * Cost-reduction taskforce (“MCD-R2”) produced a simplified mechanism using Sony’s ubiquitous '''KSS-210A''' pickup and a plastic clam-shell housing. | ||
| Line 35: | Line 35: | ||
* Combined Model-1/2 worldwide sales ≈ '''2.24 million''' units – ~70 % are Model 2 according to 1995 Sega annual report. | * Combined Model-1/2 worldwide sales ≈ '''2.24 million''' units – ~70 % are Model 2 according to 1995 Sega annual report. | ||
== | == Hardware Architecture == | ||
{| class="wikitable" style="width:70%; text-align:center;" | {| class="wikitable" style="width:70%; text-align:center;" | ||
|+'''Major ICs (VA0 main-board)''' | |+'''Major ICs (VA0 main-board)''' | ||
| Line 80: | Line 80: | ||
|} | |} | ||
== | == Differences vs. Model 1 == | ||
{| class="wikitable" style="width:70%;" | {| class="wikitable" style="width:70%;" | ||
! Area !! Model 1 (1991) !! Model 2 (1993) !! Result | ! Area !! Model 1 (1991) !! Model 2 (1993) !! Result | ||
| Line 95: | Line 95: | ||
|} | |} | ||
== | == External Connectors == | ||
* '''Expansion edge''' – identical 64-pin BUS as Model 1; ships with '''10 cm ribbon “mixing” cable''' to the Genesis 2 A/V port (carries left/right audio). | * '''Expansion edge''' – identical 64-pin BUS as Model 1; ships with '''10 cm ribbon “mixing” cable''' to the Genesis 2 A/V port (carries left/right audio). | ||
* '''AC Adaptor''' – same barrel 2.1 mm as Genesis 2 (centre positive). | * '''AC Adaptor''' – same barrel 2.1 mm as Genesis 2 (centre positive). | ||
* '''EXT Link''' – 9-pin mini-DIN to daisy-chain two Mega-CDs for dev use (never utilised by retail titles). | * '''EXT Link''' – 9-pin mini-DIN to daisy-chain two Mega-CDs for dev use (never utilised by retail titles). | ||
== | == Motherboard Revisions == | ||
{| class="wikitable" style="width:90%; text-align:center;" | {| class="wikitable" style="width:90%; text-align:center;" | ||
|+'''Mega-CD 2 Main-Boards''' | |+'''Mega-CD 2 Main-Boards''' | ||
| Line 114: | Line 114: | ||
''All revisions are cross-compatible; BIOS ROM changes (v2.00→v2.11) fix '''Lunar Eternal Blue''' save bug and 32X pass-through timing.'' | ''All revisions are cross-compatible; BIOS ROM changes (v2.00→v2.11) fix '''Lunar Eternal Blue''' save bug and 32X pass-through timing.'' | ||
== | == Audio Path == | ||
1. RF5C164 PCM → 315-5880 bus → | 1. RF5C164 PCM → 315-5880 bus → | ||
2. ASIC mixer combines FM+PSG from Genesis via ribbon audio BUS → | 2. ASIC mixer combines FM+PSG from Genesis via ribbon audio BUS → | ||
| Line 120: | Line 120: | ||
Because mixing is line-level only, Model 2 inherits Genesis 2’s famous “quiet” output (~300 mVpp). Mods: VMU Audio Amp or “Sega CD Audio Boost” board (TL072). | Because mixing is line-level only, Model 2 inherits Genesis 2’s famous “quiet” output (~300 mVpp). Mods: VMU Audio Amp or “Sega CD Audio Boost” board (TL072). | ||
== | == Maintenance == | ||
* '''Pickup lens''' – KSS-210A rarely fails; clean with 91 % IPA swab. | * '''Pickup lens''' – KSS-210A rarely fails; clean with 91 % IPA swab. | ||
* '''Spindle hub''' – plastic hub cracks; 3-D-print “clamp hub saver” or cannibalise PC CD-ROM. | * '''Spindle hub''' – plastic hub cracks; 3-D-print “clamp hub saver” or cannibalise PC CD-ROM. | ||
* '''Lid switch''' – dual leaf SW1; adjust if unit reports “Please Close Cover” error. | * '''Lid switch''' – dual leaf SW1; adjust if unit reports “Please Close Cover” error. | ||
* '''Belt''' – Model 2 has *no belt*, only a direct-drive spindle. | * '''Belt''' – Model 2 has *no belt*, only a direct-drive spindle. | ||
* '''Capacitors''' – far fewer SMD cans: primarily C224 220 µF (5 V rail) and audio coupling 47 µF (C138, C139). See [[Sega CD Model 2 Capacitor Replacement Guide]]. | * '''Capacitors''' – far fewer SMD cans: primarily C224 220 µF (5 V rail) and audio coupling 47 µF (C138, C139). See [[Sega CD (Model 2) Capacitor Replacement Guide]]. | ||
== | == Common Faults & Fixes == | ||
{| class="wikitable" style="width:96%;" | {| class="wikitable" style="width:96%;" | ||
! Symptom !! Diagnosis !! Remedy | ! Symptom !! Diagnosis !! Remedy | ||
| Line 140: | Line 140: | ||
|} | |} | ||
== | == Popular Mods == | ||
* '''RGB Bypass''' via Triple-Bypass board (VDP → THS7374 → DIN 9). | * '''RGB Bypass''' via Triple-Bypass board (VDP → THS7374 → DIN 9). | ||
* '''Region Free BIOS''' – swap 27C1001 EPROM with patched ''Mega CD Multi-BIOS v2.8''. | * '''Region Free BIOS''' – swap 27C1001 EPROM with patched ''Mega CD Multi-BIOS v2.8''. | ||
| Line 146: | Line 146: | ||
* '''S-Video + Stereo Jack''' – tap Y/C from CXD2510Q and RF5C164 out. | * '''S-Video + Stereo Jack''' – tap Y/C from CXD2510Q and RF5C164 out. | ||
== | == Technical Documentation == | ||
* | * [[Sega CD 2 / Mega CD 2 - Service Manual]] – full schematics & test points. | ||
* Yasushi Yamaguchi, “Sega CD ASIC Architecture” – Nikkei 1994 conference slides. | * Yasushi Yamaguchi, “Sega CD ASIC Architecture” – Nikkei 1994 conference slides. | ||
* US Patent 5 471 206 – “Home-use CDROM system with rotation & scale processing”. | * US Patent 5 471 206 – “Home-use CDROM system with rotation & scale processing”. | ||
== | == Trivia & Pop-Culture == | ||
* Sega’s marketing touted Model 2 as “'''2 ½ times faster'''” to load due to firmware tweaks, though the drive itself is identical 1 × speed. | * Sega’s marketing touted Model 2 as “'''2 ½ times faster'''” to load due to firmware tweaks, though the drive itself is identical 1 × speed. | ||
* Film prop in ''Hackers'' (1995) – Acid Burn’s bedroom shows a Mega-CD 2 + Genesis 2 stack. | * Film prop in ''Hackers'' (1995) – Acid Burn’s bedroom shows a Mega-CD 2 + Genesis 2 stack. | ||
* The JP manual warns: “Do not place cup noodles on top lid while operating.” | * The JP manual warns: “Do not place cup noodles on top lid while operating.” | ||
== | == See Also == | ||
* [[Sega CD (Model 1)|Sega CD Model 1]] – original front-loader | * [[Sega CD (Model 1)|Sega CD Model 1]] – original front-loader | ||
* [[Sega Mega Drive / Genesis Model 2|Sega Genesis (Model 2)]] – matching base console | * [[Sega Mega Drive / Genesis Model 2|Sega Genesis (Model 2)]] – matching base console | ||