352 Feedback SMPS Switch Mode Power Supply, Optocoupler & Programmable Voltage Reference

Поділитися
Вставка
  • Опубліковано 28 лип 2024
  • Feedback Role in SMPS Switch Mode Power Supply, Optocoupler & Programmable Voltage Reference
    i have explained in urdu / hindi language the basic function of switching mode power supply using different types of smps switch mode power supplies. smps concept and troubleshooting repairing or understanding repair switching mode power supply basics and working principle. after watching this video you will be able to understand
    1 basic working concept of smps switch mode power supply
    2. how PWM pulse width modulator work
    3. block diagram of #smps switch mode power supply
    4. practical circuit tracing of #smps
    5 how to repair mobile charger
    6 how to repair power supply of digital satellite receiver
    7. how to repair led lcd tv power supplies
    8. different faults in stages of smps
    9. what is filter and protection circuit in SMPS
    10 what is bridge rectifier circuit and how bridge rectifier circuit work
    11 what is PWM pulse width modulator circuit and how to check it
    12 function of FET, MOSFET, BJT, IGBT or switching modules
    13 what is optocoupler or opto-isolator and what is its function in #feedback circuit
    14 what is voltage regulation and how it workks in SMPS
    15 how to find problem if switch mode power supply have no output
    16 what is problem when power supply have fluctuation and output is not regulated
    17 current sense in smps
    18 short circuit protection
    19 how to test troubleshoot and repair smps switch mode power supply and easy test points in fault finding
    and much more
    TL431 Adjustable Zener - How to Use it
    How Does TL431 Work in an Isolated Flyback Supply
    What is TL431 and How to Check it Easily with Multimeter
    TL431 circuit explained as a shunt regulator
    regulator ic 431 working and how to select biasing resistor
    #TL431, #repair, #troubleshooting,
    SMPS practical tutorial • SMPS Switching switch ...
    SMPS tutorial and practical troubleshooting and fault finding • SMPS / PWM basics circ...
    • #207 SMPS Output Fluct...
    LED LCD TV power supply circuit • #219 LG LH T6240 SMPS ...
    17PW26-4 • #223 LED LCD Circuit &...
    • #218 LED LCD Circuit &...
    • #215 LED LCD Circuit &...
    • #183 How to repair swi...
    Repair ATX Computer Power Supply • #209 Repair Computer P...
    • #199 How to increase O...
    • #197 How to bypass Ove...
    • Video
    • #189 How to repair Com...
    Adjust Output of SMPS • #206 How to increase /...
    • Video
    • #206 How to increase /...
    Computer ATX power supply circuit explanation • Video
    • #168 ATX POWER SUPPLY ...
    Adjustable Zener Reference TL431,How to calculate programming resistor,adjust feedback,isolated power supply control loop,isolated bias supply design,tl431,diode,working principle,feedback loop,how to design,switch mode power supply tutorial,basics of switching mode power supply,smps tutorial,basic working of switching mode power supply,smps basics,how to repair smps,how smps work,feedback loop in SMPS,switch mode power supply,troubleshooting,PC817,optocoupler
  • Наука та технологія

КОМЕНТАРІ • 274

  • @QalbiNuuraChannel
    @QalbiNuuraChannel 3 роки тому +4

    Wcs bro thanks for sharing as always 🙏

  • @notreallyme7465
    @notreallyme7465 3 роки тому +7

    Sir I wish to thank you for all you do. I have watched many of your videos. I have learned a lot from you about switching power supplies. I never knew your trick of back feeding to test the feedback circuit. Very smart cookie you are. Thank you for all you have shared with us.

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +2

      You are most welcome
      please accept my best regards for your valuable words for my efforts

  • @megomiftah
    @megomiftah 2 місяці тому

    U are the great knowledgeable teacher rare to meet, thanks alot

  • @LimVuthyVlog
    @LimVuthyVlog 3 роки тому

    Hello my friend ..! 🙏Very nice .. Thank you for sharing ..! like ❤️❤️👍❤️💓🥰

  • @alibabacookingstyle495
    @alibabacookingstyle495 3 роки тому

    Ma sha allah 🌷🌷
    Nice sharing 🌷🌷
    Stay connected🌷
    Good luck👌🏻❤🌷🇮🇹

  • @ARA-HOUSE
    @ARA-HOUSE 3 роки тому

    Lk 9 wonderful upload dear brother ❤

  • @abrish1053
    @abrish1053 Рік тому

    Sir i have great respect for you because your explanation is different from others by many and you use your full of energy doing so Thanks so much may almighty Allah be with you!!!!!

  • @stevemiller5214
    @stevemiller5214 3 роки тому

    Thanks man! I'm now making money in Electronics Repair because of your tutorials thanks🙏

  • @mehranmohamad6924
    @mehranmohamad6924 27 днів тому +1

    actually nice .thank you. تبارک الله🙏🙏🙏🙏

  • @TYGAMatt
    @TYGAMatt Рік тому +1

    Fantastic explination. Finally very clear about how the feedback loop works

  • @carolinediyandvlog
    @carolinediyandvlog 3 роки тому

    Good morning awsome video 😁 be safe big like don full 🙈 see

  • @Elikaee
    @Elikaee Рік тому

    Greetings, Mr. Haseeb hereby I would like to express my gratitude for your sincere efforts to enhace our knowledge of electronics. I watched this video many times and it was incredibly helpful for me. Thank you for making these educational videos. You teach so nicely. Hats off to you

  • @kaupstudio-supportid5956
    @kaupstudio-supportid5956 3 роки тому +1

    MASHA ALLAH beautiful sharing, very technical and informative vlog, a big thumbs up from my side, Imran from KAUP STUDIO

  • @user-kd4ip6dy8c
    @user-kd4ip6dy8c 4 місяці тому +1

    You really a good teacher 👏

  • @Clip7heApex
    @Clip7heApex Рік тому +2

    You have a wonderful way of explaining and making things that are often quite complicated appear easy to understand. Thank you for taking the time to make these videos using your gift for teaching as they are very gratefully received.

  • @desisimplevlogs1
    @desisimplevlogs1 3 роки тому +1

    Masha Allah nice sharing hey brother

  • @mohamedantri9433
    @mohamedantri9433 3 роки тому +1

    بارك الله فيك أخي الكريم حسييب وجعله في ميزان حسناتكم استاذنا المحترم.

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +1

      السلام عليكم و رحمة الله و بركاته
      شكرا جزيلا
      كل عام و انتم بخير ان شاءالله

  • @BajisKitchen
    @BajisKitchen 3 роки тому +1

    Mashallah beautiful explanation as always thanks for sharing 👍

  • @samalamad774
    @samalamad774 9 місяців тому

    You have explained this better than anywhere else online. Subscribed.
    Just a side note: at 7:24 I believe it is best to connect the RLED to the stable post filtered Vout rather than pre filter. This will aid the stability of the LED voltage and gain the benefit of filtering.
    Great video.

  • @khaledibrahim8609
    @khaledibrahim8609 3 роки тому +1

    # 1 teacher 👨‍🏫
    Thank you
    جازاك الله خيرًا

  • @kuchpanktiyajindagiki
    @kuchpanktiyajindagiki 3 роки тому +1

    Thanks for sharing such informative upload

  • @owenpalma2982
    @owenpalma2982 2 роки тому

    I highly appreciate the you teach haseeb keep it up... it helps me a lot in my research about SMPS circuitry .... more power god bless you..

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому

      best regards and special thanks for your valuable comment

  • @TheGyimi
    @TheGyimi 3 роки тому +1

    Very informative. Thank you!

  • @nipunlakshandaluwatte9168
    @nipunlakshandaluwatte9168 2 роки тому

    Thanks, brother.. well explained.

  • @Ahmad-gn1pd
    @Ahmad-gn1pd 2 роки тому

    Jzak Allah khayr ❤️❤️❤️❤️❤️ so much respect and love from Egypt may allah bless you

  • @DIYwithBatteries
    @DIYwithBatteries 3 роки тому +2

    I like your brief explanation Sir (even better than other countries) as always :D

  • @itechfone135
    @itechfone135 Рік тому +1

    Magnifique ce court! Merci

  • @MrJamez32
    @MrJamez32 3 місяці тому +1

    Thank you very much for taking the time to make these videos, i have learned so much from you .

  • @mmohamedfaisal4230
    @mmohamedfaisal4230 5 місяців тому

    ماشاء الله congratulations ❤❤

  • @rashidkhan-pd8cf
    @rashidkhan-pd8cf 3 роки тому +1

    its like a very capable surgeon with scalpel in his hand teaching you anatomy of body.jazakAllah brother and thumbs down seems from people who's brains are pull down to ground rail 'caz of shot capacitor.

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +1

      wow. i am thankful for your valuable words.
      please accept my best regards

  • @user-ut2ii3qi6x
    @user-ut2ii3qi6x 2 роки тому

    I thank you for this good video. You explain very well! Looking forward to your new videos!

  • @rajeshnandgave3105
    @rajeshnandgave3105 2 роки тому

    Excellent explaination Thanks Sir

  • @sagartrueshayar2517
    @sagartrueshayar2517 3 роки тому +2

    w salam bhai
    very useful video

  • @mohamedkikia7338
    @mohamedkikia7338 2 роки тому

    As salaamu alaikum Bhai! This is an excellent explanation of the closed loop feedback circuit using the TL431. Keep up the good work. Your videos are very educational and informative.

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому

      It's my pleasure
      please accept my best regards and special thanks

  • @hassantj5775
    @hassantj5775 2 роки тому

    As usual, very elaborate & informative. Keep it up. Allah bless you. Ameen

  • @qaiserqureshi100
    @qaiserqureshi100 3 роки тому +1

    Masha Allah Ashraf bhai.
    God bless

  • @user-cq7vr1mo3o
    @user-cq7vr1mo3o 3 роки тому +1

    Maasha’allaah very useful please don’t forget to share and stay connected shukran

  • @temyraverdana6421
    @temyraverdana6421 3 роки тому

    Thanks, very clear explanation!

  • @Flyonwaterslow
    @Flyonwaterslow Рік тому +1

    Thank you very much, is the best content i see !!! 👍

  • @venugopalkante4111
    @venugopalkante4111 2 роки тому

    Good experience and expertise explanation, sir I request you to make video on how to use short circuit killer for fault idenfication in smps PCB

  • @MamtakiRasoi
    @MamtakiRasoi 3 роки тому

    Super sharing 👍

  • @ARA-HOUSE
    @ARA-HOUSE 3 роки тому

    Wonderfull LUX Layer ad 😊👍👍👍

  • @SAMROGER-jp5np
    @SAMROGER-jp5np 11 місяців тому

    Waalaikum salam.....
    thank you master......
    Healthy always for you..
    Salam from NUSANTARA

  • @LousyPainter
    @LousyPainter 3 роки тому +1

    You're the best Thanks!

  • @muhammadkamal745
    @muhammadkamal745 Рік тому +1

    Very informative information. Thanks

  • @MohitGupta-qm6ff
    @MohitGupta-qm6ff 2 роки тому

    Best explanation..exactly what i was looking 4

  • @vijayakumarkumar9190
    @vijayakumarkumar9190 3 роки тому +1

    Very good and useful information sir thanks

  • @daikiryoku
    @daikiryoku 2 роки тому +1

    So clear, many thanks.

  • @peymanamiri7560
    @peymanamiri7560 Рік тому +1

    Thank you bro. It was wonderful teaching. I wish all of the best for you.i have learn so much about electronic from you.

  • @haseebabdul7157
    @haseebabdul7157 Рік тому +1

    Really informative

  • @chandanbarik8782
    @chandanbarik8782 2 роки тому

    Very very thanks sir.....from ur explaination I learn so many think

  • @manafsaidusaidu9950
    @manafsaidusaidu9950 3 роки тому

    thanks haseeb sir for the this informative video..

  • @BomJimmy
    @BomJimmy 2 роки тому +1

    Superb analysis

  • @sushilchoudhary5749
    @sushilchoudhary5749 2 роки тому

    Thanks for detailed informative video

  • @tesfayebelay4860
    @tesfayebelay4860 2 місяці тому +1

    god blessed you

  • @ritinarrokomari
    @ritinarrokomari 3 роки тому +1

    I liked the video very much

  • @rashidqasmi8173
    @rashidqasmi8173 Рік тому +1

    Teacher thanks , i am going to enter. In power electronics. And i am likely bigner of age 58 year old i think i have learnt a lot from you

    • @HaseebElectronics
      @HaseebElectronics  Рік тому +1

      Best regards dera sir
      It is my pleasure that my efforts are useful
      Please accept my best regards

  • @melplishka5978
    @melplishka5978 2 роки тому

    Ty. Very well explained.

  • @idealsolution4468
    @idealsolution4468 2 роки тому +1

    Brilliant sir so so so informative Video Sir

  • @manualspellcorrect9073
    @manualspellcorrect9073 2 роки тому

    Best EE channel on SMPS by far.
    BTW, I think you meant "role" in the title.

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому

      best regards
      HAHAHAHAHAHAHA ROLE not ROLL
      loevy thanks for your valuable point

  • @wesameed824
    @wesameed824 3 роки тому +1

    Very clear explanation Thanx

  • @atulnakrani8502
    @atulnakrani8502 3 роки тому +2

    Hello sir, I always like your video.

  • @aldotambozzo9578
    @aldotambozzo9578 11 місяців тому +1

    Very useful video

  • @manilapunjabikitchen8154
    @manilapunjabikitchen8154 3 роки тому +1

    Great sharing

  • @user-pq5tz5pn4g
    @user-pq5tz5pn4g 3 роки тому +1

    السلام عليكم بتوفق دائما 👏👏👍

  • @md.kayesuddin5137
    @md.kayesuddin5137 3 роки тому

    many many tnx......

  • @rajugoud1563
    @rajugoud1563 3 роки тому +1

    Super sir your smps god.

  • @vijayakarekar
    @vijayakarekar 3 роки тому +1

    Thanks sir ji....

  • @kanchankondhare
    @kanchankondhare 3 роки тому +1

    🙏💓🌾pranam sirji very nice valuable lesson teach sirji 🌾💓🙏

  • @IS-77
    @IS-77 Рік тому +1

    Thank you so much brother

  • @msbbadsha1456
    @msbbadsha1456 3 роки тому +1

    awesome video 😱😱

  • @ChrisHalden007
    @ChrisHalden007 Рік тому

    Great video. Thanks. Small question: I have a 19v power supply with the exact circuit your described in your video. R1=80k and R2=12k. I tried to tune it to 12v by changing R1 to 47k (as you described in video 283). It kind of work, but I get a very strange behavior. Roughly 2 times per second it jumps up to 14.7 and slowly (360 ms) goes down to 12v (with no load) ?!?!? When I add a load it varies up and down 2 times per second from 9v to 12.7v. Any clue of what I should do to stabilise the output? Do I need to change Rled, capacity or led bypass resistor?!?!? I am a bit lost and confused. Monitoring the opto led with a oscilloscope i get some kind of square signal so the low side tries to do its job but cannot get rid of the oscillations somehow (( Thanks for your help.

    • @TB-jl9fr
      @TB-jl9fr Рік тому +1

      Your voltage reference is also a PI regulator. So, if your systems works most of the time it seems to me that it is "semi stable". The reason could be, that your feedback capacitor at your reference is to high, so your systems swings up some times, or it is to low, so your feedback is so slow to regulate the voltage fast enough.

  • @ahmedmadkour
    @ahmedmadkour 3 роки тому +1

    Hi beautiful brother 😍 give you super 👍 good luck

  • @FoodFunAndEnt
    @FoodFunAndEnt 3 роки тому +1

    Very informative video

  • @FancyBangles
    @FancyBangles 3 роки тому +2

    ماشاءاللہ ماشاءاللہ بھائی
    ❤️❤️❤️

  • @BricoolinoSenyor
    @BricoolinoSenyor 3 роки тому +2

    اللهم بارك
    وفقك الله أخي

  • @sudheerkumar5966
    @sudheerkumar5966 3 роки тому +1

    Very nice sir

  • @meandbabajan76
    @meandbabajan76 3 роки тому +2

    Good work

  • @Fazlubd
    @Fazlubd 2 роки тому

    brother Haseeb thank you for your tuto i just request you about MPPT solor charger and ups

  • @ezeoluchukwu5104
    @ezeoluchukwu5104 10 місяців тому

    This a nice tutorial and educative. Please can u make tutorial on how to wind smps transformer or if the tutorial is here please the link

  • @user-qh5kb7rv7o
    @user-qh5kb7rv7o 2 роки тому +2

    thank you

  • @aliduadam2761
    @aliduadam2761 2 роки тому

    Salam alaikum ,i now know clearly how this feedback works,I have bee searching for this explanation for long but I have it now mashallah,I want to know the purpose of R BIAS resistor how it work.some smp design u see a resistor at the cathode of the regulator to the 12v main voltage is it the same as R BIAS resistor or it for a different purpose.thank

  • @anlpereira
    @anlpereira Рік тому +1

    I liked the fixed option that you showed in the end of the video. For a 12V output, what Zener voltage should I use? Thank you very much.

    • @HaseebElectronics
      @HaseebElectronics  Рік тому +1

      best regards
      normally for 12 volt output
      12 volt or 11 volt can be used

  • @hkbtharanga1
    @hkbtharanga1 2 роки тому +1

    Good thanks

  • @vuthysuccessmore8551
    @vuthysuccessmore8551 3 роки тому

    Hello, hello friend, I am a new friend, thank you for sharing a good video, I like our friend, we are always good friends, I wish you good health🙏💓👋🤝🤝💓💓🙏👍

  • @AnnaHowa-dz8yv
    @AnnaHowa-dz8yv 5 місяців тому

    Thank u vm sir

  • @songzhengchen451
    @songzhengchen451 2 роки тому +1

    Thanks for sharing. It is quite clear. And sometimes I see there is an RC parallel to the 1 and 3 legs, what is this used for?

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому

      resistor connected across pin 1 & 2 is called bias resistor, it works as protection resistor to the LED, capacitor is used as bypass capacitor for protection from false switching
      as it is isolating device so there is must not be any connection between pin 1 & 3. if you experienced in some un-isolated circuit, i don't know about it. as i never observed it.

    • @songzhengchen451
      @songzhengchen451 2 роки тому

      @@HaseebElectronics Thanks for the reply. After googling, I find the parallel RC network I mean is the application of a Type two compensator.

  • @samueldavies646
    @samueldavies646 Місяць тому

    amazing tutorials thank you! how do I determine the value of the components like Rled, and the capacitor across pin 3 and 1 of tl431?

  • @mumbaiverve2307
    @mumbaiverve2307 2 роки тому

    Does the opto coupler control the duty cycle of the PWM or only enable/disable the PWM IC. Optocouplers are quite non linear devices, i think. TIA.

  • @familydonmiguel2688
    @familydonmiguel2688 3 роки тому +1

    🤗👍🏻

  • @eegayeyet
    @eegayeyet 2 роки тому

    very informative sir..keep on sharing by the way can i replace the opto coupler by a different model sir because the part number is erase

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому +1

      Yes you can
      sometime it becomes difficult due to mismatching of CTR (output current vs input current) so it causes to some trouble in output regulation

  • @Bonalafarmer
    @Bonalafarmer 3 роки тому

    Nice explanation sir.
    Pls clarify one doubt. TNY Switch/PWM switch is the only component failing each time i ON my SMPS. Pls tell how can I rectify it.

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +1

      please check:-
      1. RCD snubber circuit (resistor capacitor & diode connected across the transformer primary winding)
      2. check SMPS transformer (might be it is burnt out)
      3. check the main dc capacitor
      4. check optocoupler (output side connected to control pin of the TNY switch)
      5. check rectifier diode (connected with auxillary winding)

  • @dreamfly555
    @dreamfly555 3 роки тому +1

    So looks like the opto-coupler will output (to the controller) an Over voltage or Under voltage signal, instead of a linear signal. Is it true then the output voltage will oscillate between very slightly over and very slightly under the desired output voltage? This is because at one moment, the voltage is over the desired voltage so the controller will reduce the On time of the switching transistor until the voltage is under in which time the controller will increase the On time of the switching until it's over, i.e. oscillate between over and under. So if we were to measure the output of the opto-coupler in an oscilloscope, we would see a square wave?

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +1

      welcome dear.
      i really appreciate your pinpoint understanding. when we connect load it causes to create sawtooth ramps on capacitor in case of heavy ramps and close to triangular wave at light load or no load.
      i will explain in upcoming video using oscilloscope and multimeter

  • @vijayanathanstephen9308
    @vijayanathanstephen9308 2 роки тому +1

    👍👍👍

  • @rachidakli3555
    @rachidakli3555 2 роки тому +1

    Thanks so much for the explanations. My question is : how would behave the feedback circuit when the output voltage is higher than 12 volts (réf voltage > 2.5 volts).

    • @HaseebElectronics
      @HaseebElectronics  2 роки тому +3

      yes it is controlled by voltage divider network. in voltage divider network we have two resistors. when 2.5 volt will arrive at pin 1 of TL431 (reference pin) at that time the TL431 will conduct only. so the voltage divider network is connected between the output pins, it will sense the 12v out. if less it will decrease the reference pin.
      if the voltage will go above than 12 volts, it will provide more conduction to provide more light in input LED and optocoupler output tranasistor will saturate and it will inform PWM controller
      if output voltage are un-controlled , in the that case the auxiliary winding will provide OLP over load protection (please check video number 525 for aux winding role)

    • @Elikaee
      @Elikaee Рік тому

      Greetings, a few days ago I exactly faced this question and surfed everywhere on the Internet to find the answer; thank God, through this reply I could get the picture of feedback's reaction to the exceeding output voltage. So thank you both.

  • @ankur0077nca
    @ankur0077nca 3 роки тому +1

    Make video on voltage devider network and pull up push down resistor

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +1

      sure i will make a detailed video on pull up and pull down resistor

  • @rajugoud1563
    @rajugoud1563 3 роки тому

    Sir could you please share the video of smps in AC circuit with BIAS voltage working.kindly upload it.

  • @manafsaidusaidu9950
    @manafsaidusaidu9950 3 роки тому

    sir, after receive feed back reference voltage from cold side ( secondary) Octo coupler switching ground to pwm controller is it correct...?

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому

      yes it is correct
      there are 2 method of coupling feed back
      1, error amplifier compensation (ground is coupled to the feedback pin through optocoupler transistor, so this transistor provides the varying voltage to the PWM controller, in this way the emitter is connected to ground and collector to the pWM controller)
      2, VCC coupling (in this method rectified voltage from aux winding are applied to the collector of the optocoupler, emitter provides the vcc voltage to the PWM controller vcc pin or control pin, and it controls the supply voltage level based on the feedback from secondary side)

  • @manhardanmahedu3765
    @manhardanmahedu3765 3 роки тому +1

    Wonderful explanation as always,now I want to know what will be the internal resistance of TL431(between pin 3 and 2) when 2.5 volts applied at pin 1 of TL431?( i.e.when it allows 100mA current to flow from pin 3 to pin 2)

    • @HaseebElectronics
      @HaseebElectronics  3 роки тому +2

      as it is working as a zener regulator, so any zener regulator works in reverse biasing. so its resistance behaves as a zener resistance (same as a zener diode because zener works in reverse voltage region)

    • @manhardanmahedu3765
      @manhardanmahedu3765 3 роки тому

      @@HaseebElectronics yes sir understood, thanks for responding.

    • @marinvidovic763
      @marinvidovic763 8 місяців тому

      @@HaseebElectronics ⁸ udd6 is ooo ii 7j7

    • @marinvidovic763
      @marinvidovic763 8 місяців тому

      @@HaseebElectronicst ooop po po p poop I'll dešava wa try 9we došo s0wsIgghhb vvv a e we t7 see am in ths oo ff2f e2w o see eeď oko ooooooopppp f2f 78hghgffģfy 77is 56T66DYY6F ttþþf in r f66dt cyst rd đpr

  • @suatkaleli5075
    @suatkaleli5075 10 місяців тому

    S.A. My PS is 12 V 20 A output (S-240W-12) it has no optocoupler and TL431 but driver ic is TL494 and there are couple J13009-2 and triple C1815 instead. They the transistors all in good condition but TL494 voltage pins value shows 023 while probes between the legs pin7 (gnd) and pin12 (Vcc) at continuity mode and when 220 applied I hear some noisy voice like parasite at the beginning and at the equipment plug out/turn-off for a while (I think while charging the capacitor and discharging) and low voltage (about 5 volts) at the output. Possible to say some about that-Thanks