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Electronics Repair Questions/Answers and Testimonials -Part 73

By Jestine Yong on February 15, 2011

From Jim,

I just downloaded your Testing Electronic Components E-Book and learned more in one day then I would have reading many books over a month!

Thanks for the support!

My question is which analog and digital meters do you recommend?

For analog meter ,if possible get a Sunwa brand. As for digital meter, the Fluke 175 meter will be good.

http://www.rapidonline.com/netalogue/zoomed/Large/M061470W01.jpg

What features should I look for when buying either type? I currently have a portable Radio Shack digital (wallet sized) and a small digital I bought from Sears here in the states about 5 years ago. I’m not sure if I will go into the electronic repair business but I would like to be able to repair electronic items for myself, friends, and family.

Get analog meter that have the x10k ohm range. For the digital meter, it has to have the DC/AC volt/ammeter and ohm checking. You may buy a used unit from Ebay if you are in tight budget.

Again thank you for putting out this informative E-book!

You are welcome!

Jestine

=============================

Hi Jestine,

just finish downloading your book switch mode power supply repair , and it is really good. And want to take a minute to say that you give good customer service. Had some issues to download a book, and you gave me each time I sent you an email, a fast response. You do not only sell these books, you give a real professional service.

Can’t wait to read your next article or book on electronic. I all ready read your books 2-3 times.

Keep up the good and professional work.

Regards,

Sylvain

=============================

Hi Jestine,
How are you ? I trust you are well, I am sending you
this mail as I have been so satisfied with my purchase of the ‘how to
repair power supplies ‘ book

many regards ADRIAN.

============================

HI Jordan,

Good morning, Jestine How are you,

I’m fine thank you.

I want to ask you, Do you sell the course to fix Plasma TV? I am going to need it.

Sorry i do not have Plasma repair course. The one that you saw was from Mr Kent. He owns that website.

Let me also ask you, .Last night I was fixing one Dell LCD Monitor I do not remember the Model number, but something funny I want to tell you about, after I opened the LCD monitor inside the board trying to see if anything burn or broken, I did not see anything like that what I noticed was a little sound like tick, tick, tick and the led light was blinking in green, It is hard to determine from where the come I know it was coming somewhere the high power I removed the power FET Transistor Smps transformer but, non of them was the problem,then I decided to keep on checking I found one of the c5707 Transistor was shorted from emitter to collector I checked the other components in the area I saw everything OK. There is one of the recommendations in your book to when something like that happen check the beta with the other but I did not do it, I know it was my mistake, after that I turned the display show up after 5 second disappeared but the led now stay solid green light I found out that the same c5707 plus the the one that I did not replaced both of them were shorted in the same way they were used but they were OK. I know the the problem is coming from the inverter area it maybe the high power transformer that those transistors are working as pair with,the vcc pin 9 is 18 volts is a little high I was expecting 12 or 16 volts and the trigger from the main board was around 3 volt to the start circuit, I did not see the 2.5 volts maybe this model doesn’t use the 2.5 volts.If you have any recommendation where will be that problem please let me know about. Jestine how I can get the manual for the LCD MONITORS thanks perez

Sorry i do not have this model manual. In your case, i suggest that you check on dry joints in high voltage transformer. Another thing that you can do is to compare the top and bottom inverter circuit using ohms range. Set your ohmmeter to x 1 ohm and compare the circuits and if there is any different in the ohm reading then you know where you should trace the fault.

Jestine

========================

Dear Jestine Yong

I have got a View Sonic flat monitor( model VS10040). Of recent it developed a fault where by its displaying in black and white(display is greenish). When i try to fidget(twisting) the VGA cable at the system unit VGA port it tries to improve on its display momentarily and soon turns back to its behaviour.

on adittion i have observed that the power button is now colour orange when am using the monitor instead of lighting green.

The unfortunate part is that the VGA cable that plugs into the monitor is in built(can’t just plug it out) and has made it difficult for me to try with another VGA cable.

Am kindly requesting if you have ever got any monitor with that kind of behaviour and the remedy for such a problem.

HI Avec,

From your description it seems that the internal wires in the cable have problem. I suggest that you slowly cut open the cable (at the monitor side) and make a direct connection to the mainboard. You have to be patience in doing this kind of job. You may also refer to this website for the VGA cable information:

http://en.wikipedia.org/wiki/VGA_connector

Jestine

=======================

HI Reuel,

hi jestinei have received the esr meter.

Good to hear that.

and i have question can i use esr meter to smd capacitor?

Yes you can check SMD electrolytic capacitor only

and what the value of smd color yellow capacitor

This you need to use digital capacitance meter to check it. Different manufacturer have different value on the yellow smd capacitor.

and can i use blue ring tester to inductor of motherboard. thanks

If the inductor is big then you can test it but generally for motherboard the inductor is too small for the blue ring tester to register a value.

Jestine

=====================

Dear Jestine

Sir

a monitor LG StduioWork 505G came in tic tic sound condition. on checking HOT J6810 (Q706) and resistor (R809) were shorted and open. resistor was gused as 10ohm 1 watt, replaced. all compunets in b+ path are ok but HOT blown within 5 seconds.

kindly help

regards

Daud,Pakistan

HI Daud,

Try this link:

http://www.electronicrepairguide.com/testing-flyback-transformer.html

Jestine

=============================

HI Nasrul,

i already receive your e-book and i already read it, it interesting.

Thanks!

i need some technical advice regarding my tv problem, panasonic CRT tv monitor. can your refer image from attachment given, my tv have some line above the display, before this have problem with colour and the have horizontal line above display, colour problem i already solve it but horizontal line im still cannot solve it, hope you can help me on this ……

Check the vertical output ic area. Make sure the supply voltage is good. If there is no dry joints and the supply voltage is good then direct replace the vertical output ic and retest. Sometimes you can tune around the small preset in the convergence board located on top of the crt tube neck.

Jestine

==============================

Hi Jestine

I have a very small zener diode I want to replace but the only identification on it is that it is half red and half blue. What can be the type or value of it?

Any help appreciated.

regards

Jeff Haynes

HI Jeff,
If the board marking is ZD then it is a zener diode. It is difficult to tell the value, it could be a 6.2 volt or a 2.6 volt zener diode. 6.2 volt is more likely is the value.

Jestine

================================

Thank you very much for your reply. The answer given by you directed me in a proper direction .
As you suspected the MCU. I was a priety nervous but since you have expeirence this many times I accepted it. Now i started thinking what made the MCU corrupt? I began to search in this direction. Then i checked all the components from powersupply and the mainboard. All of them tested OK.Then i checked the front panel switches with my DMM MECO
these too tested OK.While testing these switches i found that my DMM takes a few seconds to display a reading when the switch is pressed and gradually reduces towards zero. But processors are fast enough. Now when i press the switch it does not have a zero then the processor will not read and finally it will have a wrong input. So i pulled up my Dick Smith ESR meter which has a fast display to test the switches.I found that the switch showed 40 Ohms initially and then it reduced to 8 Ohms and after quite a long time it came to zero.I checked all the switches along the PCB and found all of them behaving more or less in the same manner,So i replaced it one by one all 6 microswitches .Now i tested again with my ESR meter at the switch terminals and found to be showing 0.01..0.02 instantaneously as soon as the switch knob is pressed.Now I traced back at the connectors and checked the resistance,it was 0.08…0.09 etc.
Then I turned ON the monitor and received a nice display.Then I pressed
the OSD button it works fine till now . I made few changes to see back
if the setting remain as is .Its working absolutely fine.
That means the suspect EEprom by me was not correct.The corrupt Data fed due to contaminated switches has led to this problem.
Thanks for guiding me in the right direction.

Best Regards

Anand P

=============================

Hi Mr Yong
I know you are very busy so I shall be brief:

smoke is coming out of a component on a functioning CRT (attached photo)
I would appreciate to know:
1. what is this component
2. can it be repaired and how.

I would be grateful for your advice and help
Regards
Raza

Hi Raza,

It is a variable coil and i believe the coil won’t burnt by itself. I suggest that you clean the area with Thinner and then retest. If still sparking, the best is to replace it.

Jestine

===================================

hi jestine, i have 15 inch crt monitor acer brand, the problem is,, dim when i first open it in the morning
but after several ours it went to normal brigthness.

i already change the FBT bcoz the capacitor in FBT is change value…
cant u plz help me or give me some idea where the problem lies…

thnk u very much and more power

HI Gary,

Check that the heater voltage have 6.3 volt and G2 (screen voltage) have 250 to 300vdc.

Jestine

====================================

Hi Jestine!
I have a small smps for repair! Inside the unit on the secondary side, there is a small led going on and off( power blinking symptom).
I have checked opto-isolator, all secondary diodes, all resistors, esr. Blue ring tester shows 5 led’s. I also checked TL431- fine! My question is this: can a faulty controller chip cause this? There is also a 5 pin voltage regulator on the secondary output( even if I remove this, still blinking).
Thanx for all the help! What would we mere mortals do without you? 🙂
Riaan

Hi Rian,

Yes the small controller ic could cause such problem if you have completely check all the surrounding components. Sometimes this kind of symptom could be cause by component that break down when under load. That means you need to replace the component (usually semiconductor) and retest the set.

Jestine

================================

Problem dia sekarang nie B+ voltage drop, apakah selalunya punca B+ voltage drop.??

Hi,

Ia boleh disebabkan oleh kapasitor rosak di laluan litar B+ ataupun flybaCK, HOT dan crt yoke coil shorted. Kamu kena guna link di bawah untuk pastikan masalah di mana ie bhgn flyback (high voltage area) ataupun bhgn power supply.

http://www.scribd.com/doc/2957819/TT204-Identifying-television-SMPS-problems

Jestine

==============================

Dear Sir,

Good day to you. I would like to ask you something regarding this bridge rectifier. Can i replace the Bridge rectifier number KBP206G (600V 2Amp.) with the bridge rectifier number D3SBA60 (600V 4Amp). because in our place there’s no available KBP206G.

Looking for your reply. thanks and God bless.

Sincerely,

Randy

HI Randy,

Yes you can try that. A higher amp with the same volt is acceptable.

Jestine

=================================

THANKS FOR THE MAIL.PLEASE I WANT YOU TO HELP ME OUT.
I DISCOVER TWO POWER CAPACITOR IN THE PRIMARY STAGE OF SMPS POWER PACK BURSTED,AFTER I CHANGED IT WITH NEW ONE AND SAME RATING (200V BY 470uf ) IT STILL BURST.PLEASE WHAT CAN I DO TO SOLVED THE PROBLEM

HI Larry,
Either the line voltage to the capacitor is too high due to bad components in the related circuit or you got a bad quality capacitor. I came across bad quality capacitor before, that have blown the new cap. After replacement with other brand of cap, the equipment worked perfectly good.

Jestine

=============================

Sir,

A monitor LG505G came with PURITY and CONVERGENCE problem. it was happened by an unexperienced technician. kindly guide to fix the problem.

Regards

Daud,Pakistan

HI DAUD,

It can be caused by bad posistor or picture tube. If the demagnetizer can’t remove it then replace the tube.

Jestine

============================

Thank you Jestine for the update. A clearly understandable repair with good photos.
I had some repairs for audio equipment come my way a few years back.

One was a Shure Diversity wireless dual channel microphone system.
It had a burned up resistor on the main board. The fault was found to be an electrolytic capacitor in series with that reistor which was totally shorted. It cause excess current to flow through the reistor and burned it up. I replaced the capacitor and resistor. NO more problems.

My second project was a Peavy bass guitar amplifier. It was running with distortion on one half of a signal waveform. No problems with any of the components except when I looked at the output of the DC power supply going into the two filter caps with a scope it was distorted. What I found to be the problem was a bad capacitor across the AC input to the main bridge rectifier following the main power transformer. Just a small pF value cap was shorting out at times. I removed that small cap and installed a new one and everthing came up fine. Sounded totally clear.

Another Bass amp came to me with a different distortion problem.
A wanna-be-technician was working in this amp but couldn’t figure out what the problem was. The sound was distorted in certain stages of the amp. When I got it to my shop I plugged the amp into a variable supply transformer to bring the voltage up slowly. What I found by doing this was the amp would run fine until the voltage reached 100 VAC. It is a 120VAC system normally. After the AC voltage was past 100 volts then it would go into heavy distortion suddenly. I looked at what the earlier technician did and found he installed a wrong zener diode in one preamp circuit. He put in a 13 volt zener where there should have been a 15 volt. The diode was breaking down in operation but just barely which made the distortion happen in parts of the preamp circuit. I changed out that single zener with the correct one and had no more distortion at a full 120VAC. Problems gone.

Mark

========================

Thank you very much,what I did is,I read one of your aticle on
:understanding High Voltage in CRT monitors.
So the whole story was a Hold-down capacitor which was now loosing its
capacitance.So I changed capacitor and the problem was solved.
Thanks so much,have a good day,bye.

Happy

==========================

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15 Comments

Underfloor Heating

February 18, 2011 at 1:23 am

I know some marketers provide fake testimonials to sell their product. I'm never going to do that. I have a product to promote, but I want to obtain honest testimonials, from REAL people. Where and how can I get testimonials online? Thanks....

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admin

February 18, 2011 at 8:52 am

Hi,

I suggest that you send some sample to customer and get their feedback or you can charge them cheap in return of testimonial.

Jestine

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Amir Mukhtar

February 24, 2011 at 5:30 pm

Sir Jestine,
From yours permission, iam going to express solutions of SVGA Monitor cable faults and its diaganostics.

TIPS TO SOLVE THE SVGA CABLE FAULT PROBLEM:

Symptoms:
1. Colors hide from screen or Colors becomes change with respect to
images and picture.
2. NO Display on Screen, OR NO Data appear On Screen
3. Data Intermittently vanish when monitor touch to settings.
4. Picture Flickering.

ADVISE:

Some problems appears like above might be possible from inside monitor circuit. Therefore, need to be checked con-firmly, problems and its fault's locations.

SOLUTIONS:

In english technical empire one thing must be followed, Such as rules, Standards, and wires color coding. which are doing easy repairing and its solutions.
As SVGA connector fault is concerned, SVGA connector having 15 pin
D-type shape and pins numbers shows in it from right to Left side sequentially in standard connections.
In addition, Color coding will help you in order to soldering wires perfectly Or make data from old connector anatomy. The standards are mentioned below for your kind attention:

RED Data : Pin 1 Red wire
Green Data : Pin 2 Green wire
Blue Data : Pin 3 Blue Wire
Ground : Pin 5 Black / Shield ground
Red Gnd : Pin 6 Red Ground
Green Gnd : Pin 7 Green Ground
Blue Gnd : Pin 8 Blue Ground
Ground : Pin 10 Shorted to Pin5
ID bit1 : Pin 12
H-Synch : Pin 13 Yellow Wire
V-Synch : Pin 14 White Wire
ID bit3 : Pin 15

Also, to be noted that SVGA Connections is same in every monitor. So there is no need to be tackle hardly.

Thanks you
Regards
Amir Mukhtar

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hasan

February 25, 2011 at 1:35 pm

hi justine today i replace new universal tv circuit at gld tv but the problem is their is a gap at the top and bottom about one inch what do i do to fix this problem. THANKS FOR THE MONTHLY NEWSLATTER

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admin

February 26, 2011 at 10:58 am

HI Hasan,

You mean the problem is small vertical height?

Jestine

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Amir Mukhtar

February 26, 2011 at 3:53 pm

Sir Jestine from your permission, iam going to share my experience on Vertical height problem in TV.

Symptom:
1. Vertical height reduced from top and bottom side.
2. Vertical Line
3. Vertical height reduce from Top or Bottom(one side only).

Advise:

First of all need to be checked loose connections and Leakages of lower value capacitors in vertical section.

FOR SYMPTOM 1:

Check vertical size Variable, Capacitors lower value / leakages.

FOR SYMPTOM 2:

Check loose connections, vertical size Variable, Capacitors, open resistors in up-to 3 watts, and vertical IC.

FOR SYMPTOM 3:

Check vertical balance VRs, Vertical IC.

Thanks you
regards
Amir mukhtar

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oscar guzman

March 8, 2011 at 2:22 pm

i have a dell lcd monitor 2007 FPb,were i can find this bord 4H L2H08 A02 OR E157925,I TRY TO FIX ,but no luck.thanks

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admin

March 8, 2011 at 10:50 pm

Hi Oscar,

Try email Luca at info(at)lavinci.it

Jestine

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tariq pervez

June 5, 2011 at 9:22 am

Dear SIR.
I vist your quatin answer plat foram realy it is very knowledgable foram,sir i hav LG 505G STUDIOWORKS monitor .could you please help me .the problem in sceen where the screen pinch in vertcial ,i search on pcb board but i could foind any damage component .can please tell where is the problem and how i resolve this problem
i am waitng your prompt reply.
i hope you will reply me
thanks and best regards
tariq

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admin

June 5, 2011 at 8:02 pm

HI Tariq,

Make sure the B+ voltage is good otherwise it will have a squeeze display vertically. Check also for dry joints in the horizontal yoke coil section and make sure the yoke coil is not shorted.

Jestine

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tariq pervez

June 6, 2011 at 3:10 am

Dear jestine.
Really very very thanks for your kind prompt reply about my case.i will check acourding to your suggition.
Again thanks
Best regards
tariq

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nomee

June 13, 2011 at 3:08 am

Hi jestine,
jestine i am facing the problem in monitor HP S7500 MODLE NO.PE1163T .Actually when i open/press button for power the GREEN LED going on .after LED on rellay ativate for switching but disply not appearing .later green LED chnage in to orange but sceern disply not appeared.could you please help me for solving this problem i will be thank full to you.
BEST REAGRTS

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admin

June 13, 2011 at 8:05 am

HI Nomee,

Try use the lik below to isolate the problem:

http://www.scribd.com/doc/2957819/TT204-Identifying-television-SMPS-problems

Jestine

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tariq

July 3, 2011 at 9:10 am

Hi justine,
Sir i have a vast knowledge about electronics analoge and digital parst its working checking and testing means i have theorticaly knowledge but i dont have experience
prectically work and knowledge .Sir i want to myself how to read circuits ,how to desige circuit its working its trubleshooting.and how can i incease and improve my prectical ability of electronic circuit.like soldring,pcb circuit and so on .Sir i also want to study of industrial elecronics.could you please tell me how can i do this.I hope you will solve my case above mentiion points.hope you will replly me promptlly
Best reagrds
tariq

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admin

July 4, 2011 at 6:51 pm

HI Tariq,

I suggest that you check out the website below:

http://www.repairfaq.org/REPAIR/

visit Youtube.com to see how they do the soldering work and get books on how to read schematic from amazon.com

Remember also to visit electronics forum.

Jestine

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