Description

1. What the suffix means XAA25302M6 = sixth-generation analog hands-free board, 24 VDC loop power, DTMF dialling, auto-dial on “CALL” push, built-in line supervision, UL 864 recognized.
   Frequency response: 300–3 400 Hz per TIA-470-D.
   THD: < 3 % at 0 dBm.
   Stand-by current: 12 mA; off-hook 45 mA.
   MTBF: 100 kh @ 25 °C.
2. Safety first—lock-out & verify Although the phone is low-current, the same 24 V bus feeds the brake. Lock the controller breaker, hang a lock-out tag and wait 60 s for the rail to fall below 5 V. Keep the new Nanjing Zhuye phone in its anti-static bag until mounting—CMOS audio chips can latch at 25 V static.
3. Mechanical mounting—COP depth matters The PCB snaps onto four 6 mm brass stand-offs behind the COP face-plate. Minimum depth 35 mm; < 30 mm will crush the electret microphone. Torque M3 screws 0.4 N·m—over-tightening warps the board and cracks the carbon keypad. Re-use the original gasket; if compressed > 1 mm replace it (NY-GASK-25302) to maintain IP31.
4. Connector map (print and tape inside COP) J1 – 24 VDC & common (2-way, polarised)
   J2 – Analog line Tip/Ring (2-way, 600 Ω)
   J3 – Hands-free speaker 8 Ω, 1 W (2-way)
   J4 – Electret mic, 2 V bias (2-way)
   J5 – Program header (3-way, service only)
   SW1 – Auto-dial enable (ON = default)
   VR1 – Mic gain, ±6 dB range
   VR2 – Speaker volume, ±10 dB range
5. Wiring & line supervision Tip/Ring: 0.5 mm² twisted pair, max loop resistance 600 Ω, distance < 800 m to PABX.
   24 VDC: 1.5 mm², fuse 250 mA fast-blow in series with J1 pin 1.
   Shield: connect drain at PABX end only; floating shield causes 50 Hz hum.
   Line test: on power-up the phone sends 100 ms 1 kHz tone; if loop current < 18 mA red LED “LINE” stays on—check wiring or PABX port.
6. Auto-dial programming Default number is pre-flashed 1234; change with any DTMF phone: Pick up handset (or short T/R for 2 s), dial * 9 9 #, enter 4-digit code, dial new 12-digit number, press #.
   Success = three beeps; failure = busy tone.
   Nanjing Zhuye ships each unit with a printed quick card inside the box—stick it on the inside of the COP door for future techs.
7. Audio calibration Mic gain: speak at 0.3 m, adjust VR1 until PABX receives –20 dBm (verified on S-meter).
   Speaker: adjust VR2 so sound at 0.5 m is 65 dB(A)—loud enough for a wheelchair user, low enough to avoid feedback.
   If sidetone is weak, add 1 kΩ across Tip/Ring (supplied in hardware kit NY-HW-25302).
8. Environmental & lifetime model Electret mic capsule: –20 °C to +70 °C, 90 % RH non-condensing.
   Capacitor C1 (47 µF, 35 V) is the wear item: 2 000 h @ 105 °C, 64 000 h @ 45 °C (typical COP temperature).
   Keypad carbon pills: 500 000 cycles; at 300 calls/day = 4.5 years. Translate to building traffic: Light traffic (residence, 10 calls/day) – replace ≈ 20 years; inspect every 5 years. Medium traffic (office, 100 calls/day) – inspect every 2 years, replace ≈ 6 years. Heavy traffic (mall/metro, 300 calls/day) – inspect every 12 months, replace ≈ 4 years.
9. Preventive inspection checklist Monthly: press “CALL” for 2 s, verify PABX receives call and two-way audio is clear. Quarterly: measure 24 VDC ripple at J1; > 200 mVpp indicates supply fatigue, not phone fault. Annually: IR scan PCB; hot spot > 20 °C above ambient predicts capacitor failure. Bi-annually: torque check J1/J2 screws; vibration loosens them and creates “line fault” ghost.
10. Rapid swap (downtime < 5 min) a) Power down, tag out, wait 60 s. b) Photograph J1-J4 orientation with phone. c) Remove two COP screws, slide old phone out. d) Insert new Nanjing Zhuye XAA25302M6, torque 0.4 N·m. e) Restore connectors J1→J2→J3→J4. f) Power up, verify green “PWR” LED solid. g) Press “CALL”, verify auto-dial and two-way audio. h) Log serial number and install date; return old unit for recycling.
11. Recycling & sustainability Nanjing Zhuye offers prepaid UPS labels inside every carton. Returned phones are stripped: gold fingers go to certified refinery, ABS housing re-granulated, speaker magnet re-used. One recycled phone saves 0.8 kg CO₂—enough to power the same COP for two weeks.