Nintendo Game Boy, Pocket & Color Hub
Sharp LR35902 handheld workbench reference — DMG-01 +5V/−19V DC-CONV regulator & 6V vs 3V DC jack polarity alert, vertical LCD line ribbon reflow, CGB C38 speaker recap, and 6-pin EXT Link Cable SPI pinouts.
DMG-01 (6V Centre-Negative) vs. Pocket/Color (3V Centre-Positive) & −19V LCD Bias Alert!
Nintendo reversed the DC barrel jack polarity and halved the voltage between the original 1989 Game Boy (DMG-01) and the later Game Boy Pocket (MGB-001) / Game Boy Color (CGB-001)! Even worse, every Game Boy contains an internal switching DC-DC converter board (DC-CONV) that generates both regulated +5.0V DC for the CPU/cartridge AND a high negative/positive LCD bias rail (−19V DC on DMG-01; −18V on Pocket; +13.6V / −15V on Color) — if you install a modern backlit IPS screen on a DMG-01 or Pocket, always verify whether the old DC-DC converter can handle the extra 150mA current on +5V or upgrade to a modern CleanPower / 2A buck-boost regulator!
1 External DC Jack Polarity Matrix
| Handheld Model | Batteries | External DC Jack Spec |
|---|---|---|
| Original DMG-01 (1989) | 4× AA (6.0V) | 6V DC Centre-NEGATIVE (⊖) (3.5×1.35mm) |
| Game Boy Pocket (MGB-001) | 2× AAA (3.0V) | 3V DC Centre-POSITIVE (⊕) (2.35×0.7mm EIAJ-01) |
| Game Boy Color (CGB-001) | 2× AA (3.0V) | 3V DC Centre-POSITIVE (⊕) (2.35×0.7mm EIAJ-01) |
2 DMG-01 4-Pin DC-CONV Pinout
The small daughterboard at the bottom-left of the DMG-01 CPU PCB converts 3.6–6.0V battery input into two regulated rails:
| Pin | Signal | Expected Voltage |
|---|---|---|
| Pin 1 | VIN (Switched Batt+) | +4.5V to +6.0V DC (from power switch) |
| Pin 2 | GND (0V Common) | 0.00V Ground |
| Pin 3 | −19V (LCD Bias) | −18.5V to −19.5V DC (Blank screen if dead!) |
| Pin 4 | +5V (VCC Logic) | +4.95V to +5.10V DC (Powers CPU & Cart) |
3 Game Boy Color C38 / C35 / C32 Recap
- Every Game Boy Color (
CGB-CPU-01to-06) has three surface-mount electrolytic capacitors that fail universally with age: C38(100 µF 4V): Speaker AC coupling capacitor — when dry, the internal speaker becomes whisper-quiet or buzzes while headphones still sound loud!C32(100 µF 6.3V) &C35(22 µF 16V): Smooth the +5V CPU rail and ±15V TFT LCD bias rails; failingC35causes washed-out screen flicker and dark horizontal bars.
Architectural Summary & Handheld Generations
Gunpei Yokoi's Sharp LR35902 (8080/Z80 hybrid) SoC across DMG-01, Pocket, and double-speed Game Boy Color
$FF30–$FF3F), CH4: LFSR Noise — hard-panned L/R in stereo headphones!
Original "Brick" Game Boy (DMG-01) 1989 – 1996 • 4 Modular PCBs
The original DMG-01 splits its electronics across four separate boards: the rear DMG-CPU mainboard (housing the 80-pin QFP Sharp DMG-CPU A/B/C, two 8KB SRAMs for WRAM and VRAM, and the 32-pin cartridge slot), the front DMG-LCD board (housing the reflective olive-green STN glass panel, row/column driver ICs, D-Pad/A/B/Start/Select silicone pads, and LM358 contrast op-amp), the bottom-left DC-CONV power regulator, and the bottom-right DMG-JACK headphone board.
Complete DMG-01 Recap & Interactive Flowchart Links
We have dedicated interactive bench tools specifically for the DMG-01 on Smiggy's World:
- Open Full Game Boy DMG-01 Capacitor List (/repair/game-boy-dmg-01) → Every electrolytic capacitor value, voltage rating, and PCB location across the CPU, LCD, JACK, and DC-CONV boards.
- Open Interactive DMG-01 Diagnostic Flowchart → Step-by-step measurement tree for dead power, missing −19V contrast, and garbled Nintendo boot logos.
Game Boy Pocket (MGB-001) & Game Boy Light (MGL-001) 1996 / 1998 • CPU-MGB Integrated SRAM
The 1996 Game Boy Pocket shrank the CPU and both 8KB WRAM/VRAM memories into a single 80-pin CPU MGB QFP chip and replaced the blurry olive-green DMG screen with a larger, crisp black-and-white FSTN LCD. However, running off just two AAA batteries (3.0V nominal) means the internal DC-DC converter works near its limit — flash cartridges (EverDrive GB) plus an IPS screen on an unmodded Pocket will frequently brown out the +5V rail unless fitted with an auxiliary 5V buck-boost regulator!
Pocket Polarizer Burn & 6-Pin Compact EXT Port
- Circular Dark "Screen Burn" Blob: When the front or rear polarizing film on a DMG or Pocket degrades from UV/heat, the liquid crystal is usually still 100% intact! Carefully peel the front polarizer with a razor blade, clean old adhesive with IPA, and apply a new linear polarizer (for DMG: green tint; for Pocket: FSTN film + retarder film).
Game Boy Color (CGB-001) 1998 • 8.38MHz CPU CGB + 32KB WRAM + IR Port
The Game Boy Color doubles the CPU clock speed to 8.388 MHz, expands Work RAM to 32 KB and Video RAM to 16 KB, adds top-mounted Infrared (IR) communication LEDs, and drives a reflective colour TFT LCD that requires zero contrast wheel adjustment. Its two most common bench faults are a corroded dirty power switch (`SW1`) and a dried-out 100 µF 4V speaker coupling capacitor (C38).
Cartridge Save Battery & MBC3 RTC Crystal
- Pokémon Gold / Silver / Crystal Dry Battery: Because Generation 2 Pokémon cartridges use an
MBC3mapper with a live 32.768 kHz Real-Time Clock crystal, they drain their tabbedCR2025battery in 7–10 years (whereas non-RTCMBC1/MBC5games like Link's Awakening last 25+ years). Always solder in a fresh Panasonic tabbedCR2025orCR2032(never use electrical tape!).
Diagnostic Flowcharts & Common Fault Decision Trees
Reflowing missing vertical LCD columns, fixing black-bar boot loops, and restoring silent speakers
1. Missing Vertical Lines on DMG-01 LCD Screen
Diagnostic Decision Tree
- Peel the Black Foam Strip Below the LCD Glass: Separate the front
DMG-LCDPCB and peel off the thin black rubber adhesive strip sitting directly over the brown kapton ribbon just below the lower glass edge. - Reflow at 260°C–280°C Across the Ribbon: Using a clean chisel soldering iron tip at ~270°C, gently glide side-to-side across the brown ribbon 2mm below the glass edge while the Game Boy is powered on with contrast turned all the way dark.
- Watch Columns Snap Back in Real Time: As the heat reflows the factory conductive adhesive under the kapton ribbon, lift the iron for 2 seconds to let the joint cool and solidify until all 160 columns are solid! (Note: Horizontal lines are on the fragile right-side ribbon and are much harder to reflow.)
2. Solid Black Bar / Garbled "Nintendo®" Logo on Boot
Diagnostic Decision Tree
- How the 256-Byte Internal Boot ROM Works: The Game Boy's internal boot ROM reads the 48-byte Nintendo logo bitmap from the cartridge header at
$0104–$0133twice: once to draw it on screen, and a second time to verify every byte matches the internal ROM copy! - Solid Black Rectangle = No Cartridge Detected: All 8 data lines (`D0–D7`) are reading
0xFF(pulled high) or0x00. Scrub the 32 cartridge pins and console slot with 99% IPA. - Garbled Logo That Changes When Reseated = Dirty Pin: One address (`A0–A15`) or data (`D0–D7`) pin has poor contact. If a specific cartridge always shows the exact same corrupted logo even in a known-good Game Boy, reflow the solder joints on the cartridge's Mask ROM (`U1`) and `MBC` mapper chip (`U2`)!
3. No Sound from Internal Speaker, But Headphones Work
Diagnostic Decision Tree
- Inspect the Mechanical Cutoff Switch Inside the 3.5mm Headphone Jack: Inside the 5-pin headphone socket (`DMG-JACK` or bottom of Pocket/Color), inserting a 3.5mm plug physically pushes a tiny metal leaf contact open to disconnect the internal speaker. When oxidized, that leaf switch stays stuck open even after unplugging headphones!
- Clean Switch Contacts: Slide a thin strip of card soaked in DeoxIT / IPA between the two tiny metal switch contacts at the side of the transparent headphone jack housing.
- On Game Boy Color — Replace Capacitor
C38(100 µF 4V): If the headphone switch has continuity but the speaker is still faint, replace SMD capacitorC38and test the 8Ω 0.2W Mylar speaker coil for continuity (~7.5Ω).
4. Power Chime Plays, Screen is Completely Blank White/Green
Diagnostic Decision Tree
- Measure Pin 3 of the
DC-CONVBoard (−19Von DMG /−18Von Pocket): If Pin 3 reads 0V instead of −19V DC, the negative inverter stage on the DC-DC converter board has failed (or capacitorC9on the LCD board is shorted). - Inspect the Contrast Wheel Potentiometer (
VR230kΩ): Flush the thumbwheel potentiometer with DeoxIT F5 and check the LM358 dual op-amp on the front DMG-LCD board.
Dedicated Game Boy Connector Pinout & Recap Reference
Click below to open the interactive 6-pin Link Port diagram or the board-by-board DMG-01 capacitor table
1. Game Boy / GBC 6-Pin External Link Port (EXT) Pinout →
Complete 6-pin synchronous serial SPI pinout (VDD, SO, SI, SD, SCK, GND), DMG-04 vs MGB-008 plug sizes, SO-to-SI crossover rule, and Arduino Game Boy Printer capture guide.
2. Game Boy DMG-01 Complete 4-Board Recap Reference →
Every electrolytic capacitor on the DMG-CPU, DMG-LCD, DMG-JACK, and DC-CONV boards with factory capacitance, voltage ratings, and failure symptoms.
Game Boy Silicon, SRAM & Op-Amp Reference
Click any chip card to inspect its pinout in our IC Pinout Finder
Sharp LR35902 (8080 / Z80 Hybrid Core)
Combines Intel 8080 registers with Zilog Z80 CB-prefix bit manipulation instructions, hardware tile/sprite PPU, 4-channel wavetable/PSG audio, and SPI link controller.
Compare with Z80 Pinout → SOP-28 • WRAM / VRAM / SavesLH5264 / 6264 (8KB Low-Power SRAM)
Two 8KB 6264-compatible SRAMs sit on the DMG-01 CPU board (Work RAM & Video RAM), and a third sits inside battery-backed MBC1/MBC3/MBC5 cartridges.
Open 6264 SRAM Pinout → SOP-8 • DMG-LCD ContrastLM358 Dual Operational Amplifier
Buffers the contrast thumbwheel voltage on the front DMG-LCD board to regulate the STN liquid crystal bias rails between 0V and −19V.
Open LM358 Pinout →