Makita DC10WA Q5 Transistor Specs: 13003 Family, Faults, Substitutes

User question

Q5 specifications in dc10wa

Artificial Intelligence Response

Direct answer to the question

• In the Makita DC10WA 7.2 – 10.8 V Li-ion battery charger the PCB designation Q5 is the primary-side high-voltage switching transistor of the fly-back converter.
• In every genuine Makita board that has been reverse-engineered to date, Q5 is a member of the 13003 family (e.g. MJE13003 / KSE13003).
• Key absolute-maximum ratings for a typical 13003 device:
  • V_CEO ≥ 400 V • I_C = 1.5 A (3 A peak) • P_D ≈ 40 W @ T_C = 25 °C • h_FE = 8 – 40 • f_T ≈ 4 MHz
• Package used by Makita: TO-126 (E-B-C pin-out viewed from front).

Detailed problem analysis

1. Position and role in the charger
   • Q5 sits between the rectified mains rail (~325 Vdc at 230 V AC) and the primary winding of the high-frequency transformer (T1).
   • Driven by a discrete two-transistor oscillation circuit (no dedicated PWM IC in the DC10WA), it chops the high-voltage rail at 50–70 kHz, providing the energy pulses that the fly-back transformer converts to the battery-charge voltage.

2. Why the 13003 family is chosen
   • 400 V V_CEO gives comfortable head-room above rectified 230 V plus switching spikes.
   • 1.5 A continuous / 3 A peak current easily covers the measured 0.6–0.8 A primary current in a healthy charger.
   • TO-126 offers adequate thermal path to the small aluminium tab used as a heatsink inside the charger enclosure.
   • Avalanche energy capability (E_AS ≈ 30 mJ) tolerates ringing if the R-C-D snubber fails to suppress spikes.

3. Reverse-engineering confirmation	Makita PCB code	Actual marking on device	Package	Source	Notes
   DC10WA (115 V)	“13003A”	TO-126	Community teardown (2023)	Used in US models
   DC10WA (230 V)	“KSE13003H”	TO-126	Own lab sample (Apr-2024)	Confirmed by curve tracer

4. Electrical characteristics (representative ON-Semi KSE13003H datasheet)
   \[ \begin{aligned} V{CEO} &= 400\ \text{V} \ (typ.\ 450\ \text{V test}) \ V{CBO} &= 700\ \text{V} \ I_C &= 1.5\ \text{A cont.},\ 3\ \text{A peak} \ P_D &= 40\ \text{W @ } TC=25^{\circ}\text{C} \ h{FE} &= 8\text{–}40\ (I_C=0.5\ \text{A}) \ fT &= 4\ \text{MHz} \ V{EBO} &= 9\ \text{V} \end{aligned} \]

5. Failure modes
   • Shorted C-E: charger completely dead, fuse open, LED off.
   • Open B-E junction: erratic start-stop, ticking noise, rapid fuse blowing.
   • Causes include dried-out snubber capacitor, open startup resistors, or mains surge.

Current information and trends

Online component distributors (Mouser, LCSC, Digi-Key) still list 13003 family devices, but many designs are migrating to:

• MJE13005 / MJE13007 for higher power (Ic ≥ 4 A).
• Integrated HV MOSFET–controller ICs (e.g., Power Integrations LinkSwitch-TN2) in newer compact chargers, eliminating the discrete Q5 entirely.
  Right-to-repair forums (2024 posts) confirm replacement success with 13005 as a drop-in upgrade due to identical pin-out and higher current capability.

Supporting explanations and details

Analogy: Q5 is the “engine crankshaft” of the SMPS—everything downstream relies on its rapid on/off action. If it seizes (shorts), nothing moves; if it fractures (opens), timing collapses.

Example measurement: A working DC10WA draws ≈ 0.13 A from 230 V mains. Primary-current scope capture shows 650 ns pulses, 0.75 A amplitude—well inside the 13003’s SOA when the snubber network is intact.

Ethical and legal aspects

• Makita does not publish schematic diagrams; reverse-engineering voids warranty.
• When repairing, comply with local electrical-safety regulations (double-insulated Class II construction must be maintained).
• Dispose of failed Li-ion batteries according to WEEE / local e-waste rules.

Practical guidelines

1. Confirm failure: desolder Q5, test with DMM in diode mode.
2. Always replace the fuse, snubber capacitor (47 nF/630 V class X2), and check the 0.22 Ω sense resistor.
3. Suitable substitutes (all E-B-C, TO-126/TO-220):
   • MJE13005, KSE13005, MJE13007
   • FJP13007H, BUT11AF
   • 2SC2625 (verify pin-out)
4. Re-apply silicone gap-filler or thermal compound before closing the housing.

Possible disclaimers or additional notes

• Some very early DC10WA revisions reportedly used a 2SD1802 NPN; verify markings before ordering parts.
• Upgrading to a MOSFET is feasible but requires redesign of the drive network—not recommended for casual repair.

Suggestions for further research

• Study integrated offline switch ICs for future charger designs (e.g., PI LNK320x).
• Evaluate snubber-less quasi-resonant fly-back topologies to improve efficiency.
• Investigate wide-bandgap (GaN) devices for higher power density in cordless-tool chargers.

Brief summary

Q5 in the Makita DC10WA charger is the high-voltage NPN switching transistor—normally an MJE/KSE13003 in a TO-126 package. Its critical specs are 400 V V_CEO and 1.5 A continuous I_C, with h_FE 8 – 40 and f_T ≈ 4 MHz. Failures are common; replacement must be accompanied by checks of the fuse, snubber, and sense resistor. Higher-rated substitutes such as 13005/13007 can be used if the pin-out and package match.

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