NEC PC Engine & TurboGrafx-16 Hub
Hudson HuC6280, 16-bit HuC6270 VDC & HuC6260 VCE workbench reference — PC Engine Duo SMD capacitor leakage alert, F101 fuse & polarity guide, 69-pin EXT bus plug-and-play RGB tap, HuCard region pin swap, and 8-pin controller pinouts.
PC Engine vs. Duo Power Polarity Reversal & Mandatory PC Engine Duo / TurboExpress SMD Recap!
NEC used opposite DC barrel jack polarities across the PC Engine family: the original White PC Engine, CoreGrafx, CoreGrafx II, SuperGrafx, and US TurboGrafx-16 all require 9V–10.5V DC Centre-NEGATIVE (⊖), whereas the black PC Engine Duo (PI-TG8) and US TurboDuo require 10V–11V DC @ 1.0A+ Centre-POSITIVE (⊕) (6.3×3.0mm barrel) and the white Duo-R / Duo-RX require 9V DC Centre-POSITIVE (⊕) (EIAJ-03)! Even more critical: the original black PC Engine Duo / TurboDuo and handheld TurboExpress / PC Engine GT contain over 55 surface-mount electrolytic capacitors that leak 100% of the time and eat through the CD servo, ADPCM, and 4558 audio op-amp vias!
1 NEC Power Polarity Matrix
| Console Model | Barrel Size | Required Input & Polarity |
|---|---|---|
| White PCE / CoreGrafx I & II / SuperGrafx | 5.5×2.1mm | 9V DC Centre-NEGATIVE (⊖) @ 850mA (Uses Genesis 1 MK-1602!) |
| US TurboGrafx-16 (HES-TGX-01) | 5.5×2.1mm (wide) | 10.5V DC Centre-NEGATIVE (⊖) @ 750mA |
| PC Engine Duo / US TurboDuo | 6.3×3.0mm | 10V–11V DC Centre-POSITIVE (⊕) @ 1.0A–1.5A |
| PC Engine Duo-R / Duo-RX | 4.8×1.7mm EIAJ-03 | 9V DC Centre-POSITIVE (⊕) @ 1.0A |
2 Internal Glass Fuse F101 & 7805
- Completely Dead PC Engine / CoreGrafx / TG-16: Inside every standalone PC Engine and TurboGrafx-16 sits a soldered axial glass or miniature fuse labeled
F101(1.0Aor1.25A) right next to the power jack and bridge/protection diode. - If someone briefly touched a centre-positive plug to the socket, the protection diode clamps the reverse voltage and blows `F101` to save the custom Hudson chips!
3 PC Engine Duo / TurboExpress SMD Alert
- Black PC Engine Duo / TurboDuo: Contains ~58 surface-mount electrolytic cans. Leaking electrolyte around the three
4558dual op-amps (`IC504, IC505, IC506`), Oki `MSM5205` ADPCM chip, and CD laser servo pots causes screeching audio, dead CD spin-up, and corroded vias! - Duo-R & Duo-RX Exception: In 1993, NEC switched the white Duo-R and Duo-RX back to reliable radial through-hole capacitors!
Architectural Summary & HuC6280 / 6270 / 6260 Chipset
How Hudson Soft paired a blazing-fast 7.16MHz 65C02-superset CPU with a true 16-bit Video Display Controller
TII/TDD/TIN), timer & 6-channel 32-byte programmable Wavetable / DDA sample PSG
White PC Engine (HTG-001), CoreGrafx (PI-TG3) & US TurboGrafx-16 1987 – 1990 • 69-Pin Rear EXT Bus
Because the compact PC Engine and larger North American TurboGrafx-16 route the entire HuC6280 CPU bus, stereo audio, Composite Video, and raw Analog Red, Green, Blue, and CSYNC from the HuC6260 VCE directly to the rear 69-pin Expansion Bus, you never have to cut the shell or solder inside the console to get RGB SCART or HDMI — simply plug a modern expansion adapter (dbGrafx Booster, EDF, or SHDS3 Pro / Turbo EverDrive Pro) onto the rear 69-pin bus!
Japanese HuCard vs. US TurboChip 8-Bit Data Bus Reversal & Pin 29
- Why US TurboChips Won't Boot in a Japanese PC Engine (and Vice Versa): NEC physically reversed the order of the 8 data bus pins on the 38-pin HuCard slot between Japan and North America (JP Pins 15–22 are `D7..D0`, whereas US Pins 15–22 are `D0..D7`!), and grounded HuCard Pin 29 on US consoles so American games check region at boot.
- The 4.7 µF Ceramic Jailbar Fix (All PC Engine Models): Soldering two
4.7 µFor10 µFX5R/X7R ceramic capacitors directly between the `VCC` (+5V) and `GND` pins on the underside of the HuC6260 VCE (Pins 24/28/42) and HuC6270 VDC eliminates vertical jailbars in RGB and Composite video!
PC Engine Duo / TurboDuo, Duo-R & Duo-RX 1991 – 1994 • Built-In Super CD-ROM² (256KB) + NEC HOP-M3 Laser
The PC Engine Duo combines the CoreGrafx, Super System Card 3.0 (256KB RAM), and CD-ROM² drive into a single unit using the NEC HOP-M3 optical pickup. Because the Duo omits the rear 69-pin expansion port, getting RGB SCART from a Duo/Duo-R/Duo-RX requires an internal THS7374 RGB amplifier board wired from HuC6260 Pins 38 (G), 39 (B), 40 (R), and 44 (CSYNC) to an upgraded 8-pin DIN socket (or existing 5-pin DIN).
Duo Backup RAM Capacitor (0.047F Supercap) & HOP-M3 Laser
- Saves Disappear After Turning Off for 2 Days: Instead of a lithium coin cell, the PC Engine Duo and Tennokoe 2 / Backup Booster use a
0.047F(or0.1F / 0.22F) 5.5V Double-Layer Supercapacitor to keep the 2KB save SRAM alive. Replace it with a fresh0.22F 5.5Vcoin supercap (or upgrade the SRAM to FRAM). - CD Spins Backwards or Won't Focus on Black Duo: Before touching the `VR101–VR105` laser servo trimpots, recap all 58 SMD capacitors first! 90% of "bad lasers" on a black Duo are actually dried-out `4.7 µF` and `10 µF` SMD caps in the CD focus/tracking servo loop.
PC Engine SuperGrafx & Handheld PC Engine GT / TurboExpress 1989 – 1990 • Dual HuC6270 VDCs & Active-Matrix TFT
The SuperGrafx adds a second `HuC6270 VDC` chip, a `HuC6202` Video Priority Controller, 128KB total VRAM, and 32KB Work RAM for dual-layer parallax scrolling and 128 sprites. Meanwhile, the handheld PC Engine GT / TurboExpress plays full-size HuCards on an active-matrix TFT LCD — and, just like the black Duo, requires a 100% SMD electrolytic capacitor recap to fix silent speakers (`C40` / `C38`) and dim/blank screens.
IFU-30 CD-ROM² Suitcase Middle Gear Replacement
- In the original white `CD-ROM²` unit (docked into the `IFU-30` briefcase), the yellowing translucent plastic middle sled idler gear turns brittle and crumbles into pieces. Always keep a modern Delrin/nylon replacement middle gear on hand when servicing an `IFU-30`!
Diagnostic Flowcharts & Common Fault Decision Trees
Isolating white/grey HuCard boot screens, dead F101 fuses, and Duo CD/ADPCM audio loss
1. Solid White, Grey, or Coloured Screen When Powered On
Diagnostic Decision Tree
- What a Solid Colour Screen Means: Your power supply, `F101` fuse, `7805` regulator, 21.477 MHz clock, and `HuC6260 VCE` video encoder are all alive! The `HuC6280` CPU failed to fetch the reset vector (`$FFFE–$FFFF`) from the HuCard slot.
- Clean the 38-Pin HuCard Contacts & Check for Cracked Slot Solder Joints: Clean the flat gold pads on the HuCard with a white eraser + 99% IPA. Because inserting HuCards pushes horizontally against the 38-pin connector, inspect the 38 through-hole pins on the underside of the PCB for cracked solder joints!
2. PC Engine Duo: HuCard PSG Sound Works, But CD Music or ADPCM Voices Are Dead/Distorted
Diagnostic Decision Tree
- Inspect Op-Amps
IC504,IC505, andIC506(`4558` SOP-8) on the Duo Mainboard: Leaking SMD capacitors (`C515–C530`) pool electrolyte directly underneath the three `4558` dual op-amps that amplify Redbook CD-DA audio and Oki `MSM5205` ADPCM audio. - Desolder Op-Amps, Clean Under-Chip Corrosion & Continuity-Test Vias: Remove the `4558` op-amps, scrub the blackened pads with vinegar + IPA, repair any eaten tiny copper vias around the Oki `MSM5205` chip, and install fresh op-amps + capacitors.
Dedicated NEC PC Engine & TurboGrafx-16 Connector Pinouts
Click below for interactive SVG diagrams, 69-pin EXT bus RGB tap points, and 74HC157 controller protocols
1. PC Engine 5-Pin / 8-Pin DIN A/V Port & 69-Pin EXT Bus RGB Tap →
Complete 5-pin (Composite/Stereo) and 8-pin (RGB) DIN pinout diagram for CoreGrafx/Duo, plus the exact pin assignments (`A23 Red`, `B22 Green`, `C23 Blue`, `A22 CSYNC`) to tap native RGB off the 69-pin Expansion Bus!
Open PC Engine A/V & EXT Pinout →2. PC Engine (Mini-DIN-8) & TurboGrafx-16 (Full DIN-8) Controller Port →
8-pin controller pinout showing how the HuC6280 reads all 8 buttons in two 4-bit nibbles via the gamepad's internal `74HC157` multiplexer (`SEL` Pin 6 & `/CLR` Pin 7) and 5-player Multitap counter.
Open 8-Pin Controller Pinout →PC Engine / TurboGrafx-16 Silicon & Memory Reference
Inspect the 65C02 CPU family and 8KB Work RAM in our IC Pinout Finder
Hudson HuC6280 (WDC 65C02 Superset)
High-speed 7.16 MHz CMOS 65C02 core with 8×8KB Memory Management Unit registers (MPR0–MPR7), block memory move instructions, and 6-channel wavetable PSG.
Inspect W65C02S Lineage → SOP-28 / DIP-28 • Work RAM6264 (8KB CMOS Static RAM)
Serves as the 8KB main CPU Work RAM on the PC Engine, CoreGrafx, and TurboGrafx-16 (expanded to four 8KB SRAMs on the SuperGrafx).
Open 6264 SRAM Pinout →