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Electronic Repair Questions/Answers And Testimonials Part 8

By Jestine Yong on August 5, 2008

Hi Jestine,

I had read this month repair newsletter and came to know that you bought a new testing smart tweezer, how is it? Good? They mention that it can test SMD components on board and also ESR, So how’s the review? Because my job 80% of the circuit components are using SMD, troubleshoot it maybe abit headache, so may think of investing one of it.

Hi D,
This meter is good if you heavily deal with the smd board. It can’t test the esr, it only the test capacitor value. Note that some of the smd components you got to remove it out from the circuit for accuracy test. You can use this tester to compare the result between two similar components while the components are still on board. Have a good day!

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Hi S,

1-e-venus with vertical raster too big even controlled to low position in OSD.You have to check all the corresponding components in vertical section. Pay more attention on the capacitor and resistor

2-Discovery DMN-3002 and DMN-3006 with no display, EHT ok, but no G2, I changed the FBT but no result.

Check if the G2 circuit would pull down the voltage (directly replace the 103 2kv capacitor and retest it)

3- Relisys TE770 blows HOT. Please visit this blog post https://www.jestineyong.com/?p=403Thank you once again, you advices have been very useful for me.

You are welcome!

Hi Jestine,

Again thanks for the News letter, I think it’s really great. These are things that me and some of my colleagues do over site, and it is really fantastic that you came up with it this month.

Have a nice week, and talk to you later

Kebba

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Hi I,
How are you? Hope you are doing well.
Yes i’m fine -thank you!I guess I am going to need help from you regarding repairing a power supply circuit of a DVD player. The problem with it is that the fuse is blown off, everytime when powered up. While going through your book, I realized that this could be due to a short-circuit and so I tried with replacing the 4 rectifier diodes (1N4007) and the Capacitor (22uF 400V), but still the problem persists. So i decided to check components 1 by one.Then i tried replacing some resistors and capacitors, though the meter readings didn’t tell me that they are bad, but still the problem is there. All the components I replaced are within the primary power section and i did not attempt to check on the secondary side.

Its good to know that you didn’t give up!

There are few componenets that i found a bit difficult to test with my experience, which are,

An optocoupler – when i checked with the meter, it did not give me any readings at all. I am trying to get the exact optocoupler to replace but still couldn’t find it.

Optoisolator should have reading. if no reading at the primary and secondary side even though you set the meter to X10k Ohm then suspect the IC had turned bad.

A Power IC (VIPer22A) – I found out that there’s a very slight burnt mark on the PCB near the 2nd pin of this IC, and i suspect it is something related to this IC as well. It is not easy to find this IC in my country as well, but I am keeping on trying.

You can try remove the power IC and power on. If the fuse didn’t blow then suspect a shorted IC.

A chopper transformer – with my meter readings, it ensured the continuity. Could a short in this chopper cause a problem like this?

A shorted primary winding could cause the fuse to blow. Try remove the transformer and power “On” to see if the fuse blow again or not.

A rectifier silicon diode which is difficult to read the part id; the meter readings does not indicate any short with it, but i could not try replacing it.

If the reading is good then don’t replace it

Just got the replied from him and here is the email:

Hi Jestine,

Thank you very much for the reply and I truly appreciate your response! You know what? I tried the way you told me, starting with the power IC, where I tried by removing the IC and powering up and when I did that, the fuse didn’t blow! Just to make sure that it was the IC, I tried your trick with the 100W bulb and I found that the power IC has reached to a significantly high temperature which no other component has. So I suspected it to be the IC.

Fortunately, I was able to find a similar power board which had the same IC and I just replaced my board with that IC, and guess what? It works fine without a short! So it confimed that the problem was with the IC itself and nowhere else! Thanks to your help, just now I got the DVD player back to life!

Your help and guidance is very much valuable to me and everyone who has the love for electronics. I am sticking to your advice so will never ever give up!

Thank you very much once again, for all the help!

Best regards,
Isuru.

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Hi Jose,

Nice to hear from you and here is your questions and answers:

I may ask your favor again where to buy discounted Smart Tweezer and Ring
Tester?

smart tweezer-http://www.advancedevices.com and

Blue ring tester- http://www.electronicrepairguide.com/blue-ring-tester.html

I recently have several monitors on shop having power and with tube
lighting but no G2 and even G1 voltages. Any tips and hints are greatly
appreciated. Honestly, I suspect the flyback is not working
(primary/secondary windings) but due to no tester that can be used to prove
such said problem it remains a doubt.

There are many causes why G2 and G1 have no voltage. It could be the flyback itself bad, no B+ voltage input and missing horizontal drive waveform to the base of HOT. Somtimes a high voltage shutdown may also cause the problem you had described.

If you can help me recommend sources also where to buy semiconductors and
flyback replacement it is mostly treasured.

Try from these electronic suppliers at https://www.jestineyong.com/?cat=12

Take care and have a good day!

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Hi S,

Problem 1: Computer Monitor(Samsung),Raster monitor tersebut menjadi curved di kedua dua belah kanan dan kiri dalam 2 inci. Saya telah periksa semua komponent di bahagian Horiz dan pin-cushion.didapati semuanya ok,tetapi tidak dapat megesan fault berkenaan,voltage collector adalah 110 vdc,adakah yoke coil problem?

Kadang kala horizontal IC pun boleh menyebabkan display menjadi curve. Pernah saya jumpa eeprom data rosak mengakibatkan display curve di acer 17″ monitor. Ya yoke coil yang separa short juga boleh menyebabkan masalah itu.

Problem 2:Tv.JVC 29′,Horiz transistor selalu short setelah tv berkenaan berfungsi untuk beberapa hari(3-4 hari),transistor tersebut cepat menjadi panas dalam beberapa saat sahaja,collector voltage adalah 120vdc,adakah flyback problem,saya sudah periksa semua komponent di bahagian Horiz atau adakah power supply problem?

Cuba baca blog post saya di

https://www.jestineyong.com/?p=403

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Hi H,

First i wish to thank you most sincerely for your monthly repair articles. I am one of your ERG member from Kenya in Africa and i really enjoy your articles.

Thanks!

I came to know you through an article you have placed maybe i cant remember but was an on line magazine on how to troubleshoot G2 circuit(capacitor) and from that article only i considered you as a very serious Gentleman on what you are doing.

I’m doing my best to write more good articles for the benefits of the ERG members.

May be before i move further let say a Little about myself..am 42yrs old man, married with four kids. I have three boys and one daughter. The first born are twins boys and they are now in there last year in primary school before joining high school next year. The second born is in class 4. while the last born daughter is 3yrs now and joining schooling next God willing. I have told you about my family because i love happy families and i have noted that you too have a passion for happy family…i hope you are enjoying every moment with your family.

Thank God for all of HIS blessing, care and good health given to me and my family. There are time to work and time that need to be spent with family. Nice to hear about your background. I have two kids, one boy and one girl.

I am working in I.T. Department in a cigarette manufacturing company but i have a passion for electronics since i was young. But somehow i lost the vision but now i am getting back there. I have been taking electronics as a hobby and getting some passive income by repairing equipments for my colleagues in office and around my estate , through your advices in your articles i have decided to move out of my comfort zone and venture into more serious projects. For example i have started a small workshop here as from 1.08.08 and now is 5 days old and also hired a young man who also has a passion in electronics and i am training him on the basics.

It’s good to hear that and congrat on your new company.

Your this month article was again very encouraging and it was like God sent to me.

I’m praising him for the wisdom he had granted to me to write good electronic repair articles.

Let my explain how.. the first day i opened the workshop my assistance got an order whereby a lady came in and said that she has a tv which she wanted repaired. So the guy could not go there without me cos he is still learning. Came evening and i armed myself with my tools. The lady was insisting on quick repairing…luckily i happened to have most of the spare parts. I was JVC TV 21″. the power was was not getting in(short?). A few mins in troubleshooting i heard a sound(crack) a resistor connected across the posistor(3 legged on) has committed suicide. Did i note its value No. another problem. Then i removed the posistor from the circuit and the power started flowing well up to the main cap. But measuring the startup voltage pin i found it pulsisting and very low. I removed the vcc pin from the pcb and the voltage went up. With that i concluded the ic was shorted on that line. I replaced the str plus the posistor and the resistor which i figured to be around 150 to 470 orhms. I had a sony circuit diagram and i guessed cause they use 470orhms across that posistor i am safe.

I was getting late and hence i was lazy for use my series lamp to bring up the tv. Man i saw fire…across that resist red hot like that seen on welding machine. Outcome: all the components have replaced dead?.. yes. Remember this was my first assignment since going in the open and so i really felt very bad an i considered quiting…i felt very discouraged and that day i had no sleep. You can imagine how ur article helped me to overcome this… by the way replaced the str yesterday evening and the machine came up very well with the posistor parts. I still concinder not to have done it cos it is when i removed the posistor plus that resistor did the power move through.. the power went off before i replaced the posistor. Now let me ask you for a big favour… have come across such a case in your career? Can you please advice me what could be the problem. I will be very glad to hear your views on this senario. It is : JVC MODEL AV-20NTG24

I have never come across this problem but what you have described, it could be a short circuit in the degaussing coil. I had repaired one unit that the degaussing coil insulated material exposed to the chasis ground and blow the fuse everytime when the switch is “On”. If you have the flyback/coil tester you can actually test whether it is good or bad. Try disconnect the degauss coil and power it “On” again.

I like the way you speak the truth though its bitter sometimes but you put in very wisely. I admire your originality when tackling issues. Keep it up. Finaly i have not done any business with you but i can assure you i will be knocking at you doors with orders whenever need arises. Watch this space.

Thanks for your support!

Jestine

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Dear Jestine Yong

last month i went for my trade test in(electronic equip. mechanics)and
failed it dismally.My problem was that i did not find the relevant
training centre,as we are short of electronics training centre and tutors.
The only thing i passed was theory but practical i did not have a proper
training.I need you to help me with this practical.
(1)use of instrument & wave analysis
oscilloscope & signal,functional generators
(2)PRACTICAL ELECTRONICS
construct a power supply on protoboard,do some calculations & measurements
(3)APPLIED ELECTRONICS
recognise some oscillator circuit boards,wire switches to light up L.E.D’s
(4)ELECTRONICS FAULT TRACING
do some fault tracing on A-STABLE & SCHMITT TRIGGER equipment

Hi M,
Thanks for the email. Those topics are very big subject and i suggest that you look up from google search for many reference in those websites. I could only help out if you have any electronic repair problem in troubleshooting and repairing electronic equipment.

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dear justine i have a portable dvd novatech when i turn it on it comes
just a blue page instead of the normal screen and the dvd does nt even
spin could you pls tell me from where should begin could be the IC or?
any idea thanks

Hi F,
Thanks for the email. I wish to help but since dvd player is so cheap nowadays, i did not my afford to repair such equipment thus i can’t provide any solid solution to you-Sorry.

Jestine

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7 Comments

zed

August 6, 2008 at 12:56 pm

may be viper22a is shorted if the fuse keep blowing. i have encountered this problem.

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admin

August 6, 2008 at 1:32 pm

Hi Zed,
Thanks for the tips!

Jestine

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admin

August 6, 2008 at 1:50 pm

Hi Zed,
He has found the problem and you are right the power IC was the main caused!

Jestine

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azul

October 6, 2008 at 4:53 am

je cherche l'eeprom data pour monitor discovery mode numéro DMN-3002

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admin

October 6, 2008 at 7:37 am

Hi Azul,
Could you write in English? I can't understand your language. Thanks

Jestine

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Justice [South Africa]

February 16, 2011 at 5:09 pm

Hi Jestine your forum really makes my job easier.I wonder how will life be without you.You are a God send life saver,keep it up.You are not selfish and I wish all technician were like you.God bless.

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admin

February 17, 2011 at 7:43 am

Hi Justice,

You are welcome!

Jestine

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