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Electronics Repair Questions/Answers and Testimonials -Part 37

By Jestine Yong on October 27, 2012

Thank you Jestine for your continued support with sending monthly Repair Articles.

You might want to know that as a result of your electronic repair guides, i am now successfully working for a giant mining company in its IT and Communications department. I'm learning new things but it seems others are learning more from me due to your electronic repair articles.

Many thanks and Blessings to you and your family.

John K

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Dear Sir,

I have problem with my lcd monitor "WHITE DISPLAY"

Kindly arrange to send some tips to solve the same.

Looking forward from your kind end.

Thanks with regards,

Bikash

Hi Bikash,
White display could be due to missing supply voltage to lcd panel or the lcd panel itself have problem. If you get supply voltage to the lcd panel controller board ic then the lcd panel have problem. If no supply voltage then you may need to perform some troubleshooting to find out where the supply have gone missing.

Jestine

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Hello Jestine

First of all, thank you for response . I was trying to find a test point for 6.3 V and 300 VDC in CRT Board but I couldn’t find a Label; I’m not familiar with this components, I took some pictures from this monitor.

Is the 6.3 V could be measure at the end board; blue plastic ( CRT neck ) ? I disconnected this round board and it has 7 pins but they don't have label.

Hi Crystobal,

This is a very old monitor. First check if there is red light under dark room. If you get red light means the 6.3 volt is present. The red light could be a small dot in the neck of the tube. Next is the g2 voltage. This g2 voltage is coming from one of the transformer pin passing through a diode and cap and eventually send to the crt board through the thick fat cable. This means either one of the wire in the thick fat cable is the g2 voltage which you really need to trace it.

Jestine

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Hi Jestine
Just want to update you on the power supply.Somebody removed some of the secondary filter caps and i replaced them and the power supply came back to life.My friend gave me three of this lcd panels and all of them came on for 2 seconds with a reddish colour and then shutdown with power led still green. I opened up the panel and removed the backlight tubes and guess what. They have very dark ends some is broken and i think that this is the cause for the reddish colour and shutdown.Now i have to find the backlights somewhere for a good price to try and bring all three back to life.Thanks for all the help and great e books.
Wimpie

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Hi justin sir
i want knw some simple tricks to prepare printed ckt boards in home
pls sjjest me

Hi Siddalingesh,

Try check this link:

http://www.electronicrepairguide.com/how-to-make-pcb.html

Jestine

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sir the color blue is direct to the plug and gray is going to the switch which is 110,120,220,240volts…but when i direct the blue and grey into the plug the transformer vibrate then no reading on secondary..sir how many ohms are there in 220 volts..?

Hi jayron,

It depends on the size of the transformer . For a 300ma transformer the primary winding is about 1 to 2 K Ohm.

Jestine

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Good day,

Does ceramic disc capacitor and multilayer ceramic capacitor same. From the photo, left is 473J 50v (MLCC), and right 473Z 25V (CDC).

Can i replace CDC with MLCC. And where can i get Philips ECG Replacement Guide Book.

Thanks For Help.

Hi Too,

Basically both cap can be used on the same circuit. However in some sensitive circuit where stability is required, MLCC cap is the preferred choice.

ECG is no longer in production and taken over by nteinc.com. You can visit sayal.com to buy the NTE replacement guidebook.

Jestine

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Dear Jestine,

I believe my ASTRO decorder is faulty. Grateful if you could give couple of tips where to & what to check. I already checked but still failed to solve the problem:

2. Problem:- Need to switch on the ASTRO decorder & wait for few hours before pictures appear on the TV screen. Its getting worst now….need to wait for half a day before any pictures appear on the TV screen.

3. Please help & an early reply most appreciated. TQ very much.

Regards,

(Mr.Ting)

Hi Ting,

First make sure the power supplyis supply good and stable output voltages. Next if the mainboard use voltage regulator ics you also need to check if it has good and stable output. If all the voltages are good and stable probably the mainboard main cpu ic could have problem and replacement of board is the only answer.

Jestine

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can u tell me how to repair a lcd tv mainboard if in some parts are burned.pls help

Hi Marius,

If burnt it can't be repaired unless you have the parts and the schematic.

Jestine

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Hi Jastin,

How are you doing? i haven't email you for a long time.

I'm fine thanks.

I am still reading your ebooks, and i am getting more knowledge from them.

Noted-the more you read and practice the better you are.

Now i have 2 questions.first question, if i don't see 5v standby from the power supply, does this mean the standby circuit on the power supply is bad?

Yes you right.

can the main board cause the 5v standby disappear?

Yes it can provided if something shorted along the 5 volt line.

Another question, when i push the power button, the PS-ON is 5v, then after 10 minutes, the PS-ON 5v goes off automatically, but the 5v standby is still there, does this mean the mainboard cpu has problem?

Yes it can be the CPU/EEPROM or related component problem.

Jestine

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TV SONY Problem no power, check output voltage all drop. 130v drop to 90v, 25v drop to 10v, 16v drop to 4v. overall output voltage drop. primary side component already check no finding. what suspected component at secondary side.?

Hi Shamsul,

It can be bad opto ic and related components, bad current resistor or even leaky components in the secondary side. You may have to break the B+ line and connect a light bulb to see if the high voltage section pulling down the voltages or not.

Jestine

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Hi Jestine,

Thanks a lot for all the Technics that I've learned from your books you produce. Today I can already repair some type of appliances at home and in my community. I appreciate this so much. thank you.

joey

phils.

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Hello Jestine,

I'm moved to "blow my cover" today (I refrain from posting anything/anywhere most all of the time because I'm always striving to be as invisible as I can be – bad for business, but I'm not in and seek not to be in business, but I respect greatly those who are and do – to let you know I'm another of those (many, many, I hope) who deeply appreciate what you have done, and continue to do, to help those who would like to be able to FIX electronic thingies of various sorts. Today's (for me) item courtesy of Mr Beh on how a simple mains cord replacement could fix a battery-saver problem made feel so grateful I just had to send this.

God (yours) bless you, Andrew.

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Its long since i communicated but am fine, op you too. thanks for the tpdates. I have a 14" tv that has secondary power problem when i switch it it swiches on but the standby LED goes off but the tv is still on, i have tried to measure voltages on the sec power and found that voltages are low eg 110v give 75 v, 24v gives 18v what might be the problem thanx.

Hi Elahuya,

In your case have you check if the CPU is getting 5 volt supply or not because the power LED signal is coming from the CPU. Your problem could be the standby problem thus no full power output from the power supply.

Jestine

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Hi Justine

I have a 51cm SANSUI TV PCB which is working and a 74cm SANSUI TV board, is it possible for me to use the 51cm on the other TV, and what modifications do i need to do to use it?

William

Hi William,

It is possible if you know all the spec (voltages, current, waveform and etc) at the connectors. It is not easy just to use other board than the original because you need to take eeprom data into consideration. Sorry i don't have info on such modification because it will take so much time to adjust everything back to original.

Jestine

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Hi mr yong i have a 14" crt tv ,after insulating eht cable when i put power on the vertical ic la78040 get shorted after replacing the ic no screen come out .i checked B+ to the flyback was ok but no eht,no g2 current .help

Hi Obert,

Have you check if there is any pulse to the base of horizontal output transistor? In order to produce high voltage and g2 voltage the flyback has to be good, must get B+ voltage and the base of horizontal output transistor must have a square pulse.

Jestine

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Hi mr jestine yong
l appreciate for all articles you send to me, they have increased my repair skills,you are such amazing person may God bless you for sharing your knoledge with us goodday.
Richard

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Dear Sir,

I have on LG monitor (CRT) having no LED indicator glowing but 5v supply at microcontroller is ok but reset pin voltage is 3v. When i press the power switch, then there is no voltage variation at crystal pin. I suspect it is a microcontroller problem. I need your confirmation because it is not easily available and costly too.

Regards

Gopal

Hi Gopal,

Yes it seems the microcontroller have problem because the power LED signal is coming from the microcontroller. The eeprom IC may be the cause of problem too.

Jestine

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Sir Jestine,

I have question regarding to my power supply unit, whenever i shutdown the PSU for about 12hrs the unit is getting hard to start again, but after the unit is ON state for about 30mins it works just Fine, do you experience this type of problem. I check the Power Fet already, looks OK in the meter,

So now im afraid to shutdown the PSU because it will take too much time to work normally, im only facing the problem whenever I turn OFF the power supply for about too long but it works normal whenever it charges the unit,

which section should i focus on troubleshooting.

Tnx & God Bless Sir Jestine

Albert

Hi Albert,

Try direct replace all the filter cap in the primary and secondary side and retest.

Jestine
http://www.JestineYong.com

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Good day Sir Yong !
I have finally solved the ''No Power Problem''. When I uncased the TV set, I noticed that all the components in the primary side of the power where okey and the fuse was intact. After brainstorming on this issue, I decided to carry out a continuity test on the tv power switch.
Afterwards, I realized that the problem was from the power on switch. when I changed it, the tv set was fortunately restored.
Glory be to GOD through Sir Jestine Yong whom He has been using in diverse ways to solve many world problems.

Best Regards
Owoh I.C.

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Hi Jestine To start with many thank for all the newsletters i get from you, all are saved so that i can return to them and enjoy over and over again. All of the tech info you give is very useful and interesting..I do however have a problem with a hanton monitor H 320 WDB This i am told was purchased new as a spare but never used, It looks to me that some resistors and caps are missing and it is now out of guarantee.. My problem is that i can not locate any schematics or circuit diagrams to help me, i have tryed all the ones in your news letters.. Do you have any other sites i could try, your help if you can will be very much appreciated, My very best wishes to you Regards jd brown

Hi JD,

Missing components is one of the toughest to repair. Try check out this link:

http://www.electronicrepairguide.com/schematic-diagram-comparison.html

or you may need to try some free and paid schematic link:

https://www.jestineyong.com/category/schematic-diagrams-website/

Jestine

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Hi Jestine if i purchase Troubleshooting & Repairing Switch Mode Power Supplies E-bookdo I have to purchase a OSCILLOSCOPE to repair SMPS

It is optional but having a scope will make your troubleshooting easier because you do not need to guess ifn a signal is present or not.

I used one 15 years in basic electronic class never master it but if I do need one I will have to learn to use one what MHZ BANDWIDTH SAMPLE RATE DUAL OR SINGLE CHANNEL ANALOG OR DIGITAL
is best to get I trust your opinion thank u

In the market most are the 2 channels. You can buy a digital or analog scope and if possible get one with 100MHZ so that you do not need to upgrade again.

Jestine
http://www.JestineYong.com

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hello Mr Yong thanks for all that you do i enjoy that so much.i need help with IC. is there a difference between srn310r36A and SRN310R36? ONE has an A. i do not have the data sheet.Th question is can i use the one without the A in place of the one with the A? thanks

Hi Corriete,

It is hard to tell because some sensitive circuit will not work even have the extra number behind. You may have to try it. Check out the link below:

https://www.jestineyong.com/is-tea1504-ic-and-tea1504ap-same/

Jestine

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5 Comments

Bradley Brake

October 28, 2012 at 4:32 pm

Lots of good answers to problems that you give service people. Keep up the good work.
Bradley

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- Jestine Yong
  
  October 29, 2012 at 4:21 am
  
  Hi Bradley,
  
  Thanks.
  
  Jestine
  
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dicksy

October 30, 2012 at 10:53 am

hi justin
thanx a lot for sending me news letters and repair articles.i was able to get lot of very important things from them.justin i hope to buy ur e-books in the future.but my question is do i need a scope to repair LCD tvs.bcoz in my country scopes are very expensive.
thanx

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- Jestine Yong
  
  October 30, 2012 at 8:34 pm
  
  Hi Dicksky,
  
  If you have the scope it would be better because you do not need to guess if an IC or circuit producing waveform or not. However, when we do electronic troubleshooting we don't use it everytime. You can try ebay.com to buy the cheap scope.
  
  Jestine
  
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prakash

March 31, 2018 at 7:14 pm

Dear Sir,

I have problem with my TCL Chaina kit vartical ic inserted pin no 4-5 shorted

Kindly arrange to send some tips to solve the same.

Looking forward from your kind end.

Thanks with regards,
prakash

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