4N35 — Test SOP

D926 Dent Puller · Swastik Automotive · zero-cross sense circuit
SOP No: SWA-D926-4N35-01 Rev: 1.0 Date: 17-Jul-2026
⚡ SAFETY: Board pe 220V AC LIVE rehta hai. 4N35 nikalna/lagana ho to pehle machine OFF / unplug karo, phir hi socket chhedo. Reading lene ke liye hi wapas ON karo, probes haath se pakadte waqt insulated hisse se pakdo.
🧰 Chahiye: Digital multimeter (AC V aur DC V dono mode) · Board box khula (bina cover)
🔊 YE TEST KAB KARNA HAI
1
Power aur Time
set karo
→
2
Gun se
trigger karo
→
3
Buzzer aur
Pulse LED
dekho-suno
✔ SAHI MACHINE
🔊 💡
Beep + LED sirf utni der
jitna Time set kiya tha
…phir apne aap BAND
✘ 4N35 KHARAB
🔊🔊🔊 💡
Beep + LED rukte hi nahi
LAGATAR chalte rehte hain
…band hi nahi hote
Beep rukta hi nahi = 4N35 gaya hua ho sakta hai → neeche wala test karo
Aisa kyun hota hai: Buzzer aur Pulse LED batate hain ki weld pulse chal raha hai — jitni der SCR fire hota hai utni der dono on rehte hain. 4N35 hi PIC ko batata hai ki AC ki lehar zero se kab guzri (zero-cross). 4N35 mar gaya → PIC ko timing ka koi sahara nahi milta → pulse khatam hi nahi hota → beep aur LED lagatar chalte rehte hain.
📐 Ye naksha PCB ke hisaab se hai. Board pe jaisa laga hai waisa hi — “−” upar, “+” neeche. Zener (D5) ki kaali patti neeche, yaani “+” ki taraf.
1
220V AC — input pe
🔊 Awaz me suno
METER YAHAN LAGAO
100k/2W U12 100k/2W U13 DB207 D1 AC AC − + kaali patti D5 5.1V U9 4N35 2 1 220V(P) 220V(N) 220 AC V V∼ COM VΩmA
AC hai — laal/kaala ulta-seedha koi farak nahi
ASLI PHOTO — meter ki reading
meter 219.6 AC
219.6V ∼ AC
✔ 200–240
SAHI
✘ 0 ya kam
supply nahi aa rahi
Ye sirf itna batata hai ki board tak 220V pahunch raha hai.
2
DB207 ke AC pin pe (resistor ke baad)
🔊 Awaz me suno
⚠ 4N35 NIKAL DO — socket khali hona chahiye
METER YAHAN LAGAO
100k/2W U12 100k/2W U13 DB207 D1 − + D5 5.1V 4N35 NIKLA 220V(P) 220V(N) 6.13 AC V V∼ COM VΩmA
AC hai — laal/kaala ulta-seedha koi farak nahi
ASLI PHOTO — meter ki reading
meter 06.17 AC
6.17V ∼ AC
✔ 6 ke aas-paas
resistor + zener SAHI
✘ 0 = 100k uda hua
✘ bahut zyada = zener kharab
Zener DC ko 5.1V pe kaat-ta hai; bridge ke do diode ~1.4V aur jodte hain → AC side pe ~6.5V. True-RMS meter ne 6.17V dikhaya. Probe DB207 ke AC pin pe hi hai.
3
Zener (D5) ke aar-paar
🔊 Awaz me suno
⚠ 4N35 ABHI BHI NIKLA HUA
METER YAHAN LAGAO
100k/2W 100k/2W DB207 − + kaali patti D5 5.1V 4N35 NIKLA 220V(P) 220V(N) + − 4.99 DC V V⎓ COM VΩmA
DC hai — laal neeche (+), kaala upar (−)
ASLI PHOTO — meter ki reading
meter 4.998 DC
4.998V ⎓ DC
✔ ~5V
zener SAHI
✘ ~0.7V = zener ULTA laga hai
✘ 0 ya bahut zyada = kharab
5.1V ka zener halke load pe ~4.99 dikhata hai — bilkul sahi. Agar 0.7V aaye to zener ulta hai — kaali patti ghuma ke “+” (neeche) ki taraf karo.
4
4N35 ka LED — pin 1 aur 2
🔊 Awaz me suno
✔ AB 4N35 LAGA DO
METER YAHAN LAGAO
100k/2W 100k/2W DB207 − + D5 5.1V U9 4N35 2 1 220V(P) 220V(N) + − 1.088 DC V V⎓ COM VΩmA
DC hai — laal pin 1 pe (neeche), kaala pin 2 pe
ASLI PHOTO — meter ki reading
meter 1.082 DC
1.082V ⎓ DC
✔ ~1V
4N35 ZINDA HAI
✘ 0 ya ~5V
4N35 MARA HUA — badlo
Ye sabse asli test hai. 4N35 ke andar wale LED ka forward voltage ~1V hota hai. ~1V aaya = LED chal raha hai. Agar ~5V aaye — matlab LED conduct hi nahi kar raha, 4N35 mara hua hai (tab zener wapas 5.1V pe aa jata hai).

❌ Ye GALTI mat karna