Electronic Repair Questions/Answers and Testimonials- Part 29
Hi Jestine,
I wanted to let you know how much I’ve enjoyed your Books and reports. They have inspired me to go into new areas of my repair business in computers, instead of having others do the electronic repairs for me as they have in the past. Being an American, I have struggled with my morals in this business for years because of high competition. I have to tell you, I really thought I would never come across another person that had the same philosophy as I did on sharing their knowledge and skills with others and answering questions freely. I once did this and was a very happy person. Now you have reaffirmed my commitment to living a good life once again and helping others. You are totally right about this, and its extremely important to being happy with your life. You are halfway around the world from me, but I feel as though I have known you as one of my best friends. You have changed my life Jestine, and I hope one day I can come to your country and meet you and your family.
Best Regards,
Dr. R.M
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Hi Justine
Just to mention that I have put your ebook to good use and succeeded in repairing my first LCD Monitor! I acquired a Blue ESR kit and built the meter and used that meter to find some ‘duff’ electrolytic Capacitors on the power board. I ordered the new capacitor replacements of the same rating and soldered them in place and reassembled everything and the monitor worked fine!
Thanks
J.H –
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My name is Martin, I’ve recently started learning how to repair computers, monitors, tvs, integrated circuit boards, etc… I’ve bought several of your online downloadable pdf files, which have been very instructional, helpful and insightful.
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hi jestine, you are wounderful, even though i haven`t read all your books, i most confess here that you are a great teacher the way you explaine your point even a non tv repairer can read and start troubleshooting the next minutes.do you know i never knew what was call flybacktransformer?.it was after i read and saw the picture of a flybacktransformer. i thank god i have found a master like you to guide me as far as troubleshooting is concern and being the most difficult task in electronic repair.
T.D.E
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Sir gud day I have a question about the Samsung
monitor sir..i hav a problem with the display,its sems ther is no problem
wen I turn on but thers no display..wen I off and trun on again it wel
display and missing again.
C.S.V
When the display missing again, does the high voltage still there (24kvdc). If no then i guess you have to make sure the B+ voltage is good. if the b+ voltage too high it will cause the monitor to shutdown when power on. If the voltage is still there then i suggest you measure the g2 and the heater voltage. Without these voltages there will be no display. Hope this helps!
Jestine
http://www.JestineYong.com
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Respected J YOUNG
Its brillant for beginers.Sir is there any stuff about motherboard troubleshooting & repairing, if yes please forward me.
Thank You
M.S
Hi M.S,
Try this link:
https://www.jestineyong.com/?cat=43
Jestine
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Hi,
My name is David and i did order your book(s) about 1.5yrs ago. They have served me really well.
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Yong,
Electronics is becoming simpler through your advice. I thank you for your help and timely updates on new challenges in the electronics world.
Keep it up and I will always keep in touch with you and thanks for the newsletter
Ishmael
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I have a laptop that has power to it as the lights come on and the fan works but after aboat 20 seconds it shuts off, i know i could just change the harddrive into another but i like a challenge so could you please give me some advise on how you would go aboat testing the resisters/caps/diodes etc all surfacemount and is there away of checking the ics any help would be greatly appreciated thankyou
If it is shutting down this could mean the problem in the power module. To check the smd components you have to use the smart tweezers and as for checking the ic you need a scope to test the output voltage from the output pin of the power ic. First the IC has to have supply voltage. From your description i suggest that you check all the filter cap in the power module first. Hope this helps!
Jestine
http://www.JestineYong.com
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I assume that this message below you just sent me was generated do to me signing up to your news letters on your website. Which is no problem whatsoever. Because I already bought your Ebook and emailed you on a question about some testing equipment I need to purchase.And I hope you don’t mind me taking a few minutes more of your time but I have to tell you.
No problem and thanks for the support!
I can’t believe the details in your story and how they compare to me. Just today at work I told my co-workers what I had been doing for some 3 weeks layoff. I said to them that I always LOVED electronics even as a little kid but the times I tried to take courses on the subject I was overwhelmed with theory and details. I told them that the one study book I worked out of not only explained the purpose and markings of resistors and capacitors, but also went onto the construction of them and how they work at the atomic level LOL 🙂 I was more than halfway through this lengthy book and all I could measure was resistance in a circuit. (whoopee) I was very intimidated and discouraged,and thought that I would never learn why something like my computer power supply stopped working and how to test the components to see if it was worth fixing.
So I went on to tell my friends that I had come across an Ebook online, I told them it was just something I downloaded to my laptop to sit and read with my time off, I said that finally I have started to learn and have some confidence in actually testing and fixing electronics. I said to them that instead of all the boring details like before that this book “cuts right to the chase” and describes with pictures what all the components are and how to test them. I’m in my 40’s now and have needed your teaching approach all my life, as they say better late than never! Thank you very much for taking your time to help others.
You are right better late than never! In fact i got couple of emails too that they need to find some sort of income after they got retrenched from their workplace and they too stumbled upon my ebook and glad to had it. John if you have any electronic repair questions just email me and i will make sure you can become a professional electronic repairer in the shortest time. Feel free to visit my blog as it contains lots of repair tips that you need to absorb at this moment. Have a good day!
Jestine
http://www.JestineYong.com
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I have problem, perhaps you can help me with it:
We service laser levels for surveying. These units transmit a low power (<5mW) laser from a laser diode. Sometimes the diode power circuit becomes faulty and destroys the diode (replacement diodes are v. expensive from the manufacturer).
How can we test the diode power circuit without using a replacement laser diode? How can we test the laser diode without putting it into the power circuit?
That would be difficult to test without the power diode. I suggest that you use the laser power meter at https://www.jestineyong.com/?p=153 to confirm that the laser diode was not the cause and then you concentrate on checking the components in the power circuit. If all of the components are smd type then i suggest that you get this meter smart tweezers to simplify your job.
Have a good day!
Best regards,
Jestine
http://www.JestineYong.com
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Hi Jestine,
Going thru. your electronics repair kit these days I am able to successfully solve quite a few debug faults on the GPS navigation system.
Thanks for your guidance.
Regds
Bharath
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I have a ViewSonic lcd panel monitor, 15 inches, Model VG150. On the sign in page for Windows XP, the monitor is fuzzy with black lines. I have tried to adjust the fine tuning and auto adjust controls. It works fine after about 20 minutes of adjustments escept the fuzzy and shaky images begin to appear again but not enough to be unreadable. When I turn on the computer later, the same thing happens again. I also have a fluorescent lamp near the computer. Any help you can offer will be greatly appreciated. Thank you.
Hi Peg,
It seems like your lcd have electronic problems. It could be bad electrolytic capacitors or even dry joints in the board. Guess you have to remove the cover to inspect the fault.
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OK thanks, I’ll try that.
Now, I have a real challenge (for me)!
I replaced all the inflated caps in a computer 400W SMPS, and all output voltages look good, when measured on a voltmeter – 12V, 5V, 3.3V, etc The motherboard even boots up OK, but not for long. Then the MB freezes.
(If I connect another PS, then the MB works just fine for as long as I want) I can hear a high-pitched squeal – I presume it is from the Mosfets, which are oscillating, but not sufficient load maybe.
What could be the cause for this apparent good voltage, but not good enough?
If it can work and producing good voltages and suddenly freeze, this could indicates dry joints in the board. Try gently knock on the board and see how it goes. Check also the small e-caps in the primary side area with esr meters.
Jestine
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Happy Chinese New Year to you. I am glad to hear you again after the holidays.
Same to you Happy Chinese New Year!
After rechecking the GTC monitor, the tictic sound was caused by the HOT had not been resoldered, I just put it back and forgot to resolder it, and it caused one of the IRF 630 to break down.
Now after resoldering the HOT and replacing the bad mosfet, the monitor is back to the condition where the led power indicator can stay green while there is video signal, but there is no picture at all ( completely dark ).
Make sure the B+ VOLTAGE is going to the flyback and the h driver signal present at the base of HOT.
My sister had brought me high voltage probe now, and when I want to use it, I wonder where to put the black alligator clip.
Because now I notice there are 3 kinds of ground on the monitor: one is the hot ground, one is the chassis or cold ground, and still another one is the peel-off cable running on the back surface of the CRT; all the grounds are isolated from each other. When I read your article about “Using High Voltage Meter or Probe to Repair Equipment Problems Fast”, I could see that you are using the peel-off cable. At first I thought this would be the same with the cold / chassis ground, but after checking with multimeter, the needle doesn’t move at all which means they are isolated from each other. So, I was confused about which ground should I attach the alligator clip of the HV probe.
Clip it on any cold ground preferably the ground at the picture tube.
And because the picture in your article showing you were attaching on the peel-off cable, then I follow your method, but unfortunately when I insert the probe tip to the anode cap there are some sparks on the tip. I am wondering why this happens, is it because I was connecting to the wrong ground or I should not drag the HV probe tip to the anode cap while the monitor is on, because the dragging action will leave scratch on the red circle beneath the anode cap
I suspect the cold ground from the CRT tube did not reach to the ground (spring) that attached to the picture tube. By right it should be connected and the ground at the picture tube is the same as the ground in the CRT or the mainboard.
Could you explain in more details how should I make the measurement of the FBT anode? It really makes me scared.
Do I need to ground-short the FBT anode first each time before I remove the anode cap, because each time when I do this, I add more scratch on the red circle beneath the anode cap ( I use screw driver to do it ). What tool should I use to short the FBT anode so that it won’t leave any scratch?
Actually it is a simple process. First place the probe to the anode and the clip to cold ground. Now switch on the Monitor and read from the scale. Your spark problem could be the missing ground connection. Infact during my early days in monitor repair i had been sparked before and the feeling was pain in the hand for couple of minutes and after that it was okay.
To my surprise after some sparks happen when using the HV probe, the display now appears, but the picture is flickering and not stable, sometimes disappears again and comes again shortly. Could you explain it to me why the display now suddenly appears? Next, how to solve the flickering display?
Check the ground and it could have loose connection.
I want to measure the heater voltage, but don’t know where to do it, is it on the socket of the CRT? Is it DC or AC voltage?
Yes you can measure the heater voltage at the socket or from the secondary side of power supply and is in DC voltage (6.3 volt)
But just now I read the Q&A in your blog saying “For your information our meter canʼt measure the high pulse of the heater voltage.” So how should I measure the heater voltage, does it need special meter?
That answer was for TV because TV heater was derived from flyback and flyback produces very high frequency that our meter can’t read it unless you have a special meter. Without special meter we also can check it by looking at the glow in the picture tube. Without the glow (orange light) means there is no heater voltage.
When I pull out the VGA cable, sometimes the greed led power indicator keeps lighting; doesn’t it have to go amber at once?
It depends on the deisgn of the Monitor but generally newer Monitor would blink or turn to red LED.
Jestine
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What is the use of the red circle beneath the anode cap at the back-top of the CRT surface? Does it have opposite polarity to its surrounding?
It is isolated from the aquadag ground (the black paint at the picture tube). if you use your meter set to x10 k ohm and measure the black paint it should show some reading.
What is the highest normal temperature of any components on a monitor’s main board? I’m asking this because I have an Extech DMM 470 which has IR thermometer feature which can scan the components onboard, and this should help me in finding any bad components.
I have not tested the maximum temperature before because normally i will use my finger to test the temperature of the components. I suggest that you test it and keep the record for future reference.
Jestine
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Thanks for your quick reply. Sorry I didn’t mention, but it shuts down even with the backlights disconnected.
For your information, a good lcd monitor will shutdown if you pull out the back light.
I have narrowed down that the problem is in the screen itself and not the power supply, main board, inverter or backlights. I’m not sure how to explain this properly, but say I have 2 different LCD panels, and one power supply and main board. I can hook up one screen and it will work perfect, but if I hook up the other screen, then it shuts down. I have seen one where it will blow the fuse at the screen connector when it’s plugged in, but I replace the screen and it works perfect.
I can then take the bad screen and hook it up in other perfectly working monitors, and it will shut them down as well. When it shuts them down, the secondary voltage drops low as if there’s a major short in the screen. If I use other screens in the monitor that the bad screen came out of, they will work perfectly. The only conclusion that I am able to come up with is that the screen itself, or at least the controller mounted on the screen itself is completely shorted.
From your test it is confirm that the lcd panel have problem. Just before you confirm that the lcd controller ic in the panel was the cause why not test out the smd capacitor for short circuit as this tiny shorted cap could pull down the secondary voltage.
Jestine
http://www.JestineYong.com
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Hi Mr. Yong, i really enjoying read your book!
M.M
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I am wondering how your books will work for me. I just got the capanalizer 88 and a
Leakseeker 82b and do not know how to use either. My goal is to learn how to use these items with a digital multimeter. How will your books do this?The key for me is learning with The capanalizer 88 and the leakseeker.
My book does not cover on how to use leakseeker 82 b. The function of this meter is to locate short circuit in a motherboard that have lots of components. I believe the manual have some good explanation how to use the meter. As for the Cap 88b, it is a ESR meter and i recommend that all electronic repair technicians should have one. I owns the cap 88b, dick smith esr meter and the Blue ESR meter too. The ebook contents mostly deal with how you can use many different types of meters to accurately test electronic components.
Best regards,
Jestine
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I have a problem with my dell E173fbp monitor. the problem is a little different from what you have explained in your article on repairing a faulty e173fbp as explained by Jestine Yong.
When i switch on the monitor, it operates quite fine for the first 20 minutes. and when the back of the monitore gets hotter, the display goes off…not the whole power. when i disconnect the VGA connector, the standby display shows for few seconds and goes off. reconnecting the VGA, the dispaly comes back but for few seconds it goes off again. If i switch off completely and on again, it shows for for some minutes and goes off again. if i take a fan and place place it behing the monitor, it does not go off.
Hi Ishmael,
From your description it seems like more on dry joints problem. Try gently knock on the monitor with your hand while it is running. If it shutdown then you know it is a dry joints problem.
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Good day to you, Mr Yong,
After battling for 8 months obtaining parts for my BenQ LCD monitor, and with your precious assistance, I managed to fix my monitor at last!
I worked for a day, logged off like any other day. Last night, however, when I switched on my pc, my monitor had a RED screen. I have checked, but cannot find any fault.
Have you experienced this before?
Love to hear from you..
Hi G,
If you could not see any character and only red screen then most probably the lcd panel have problem. Make sure also the flex cable between the mainboard and the lcd panel is not loosen.
Jestine
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Mr. Jestin Yong good afternoon my name José in
P-CHANNEL POWER MOSFET 2SJ598 NEC Q751 IN SHORT In C. Rica are not Tell me how can achieve this transistor is the monitor for personal use and the cost per unit C5707 transistor and thank you very much and God vendiga together with his family.
Hi Jose,
Try order the parts from http://www.bluestar-online.com
Jestine
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Thanx loads for your note on the ESR meter – forgot about this aspect of
e-cap operation! Did some investigating on this online after I got your email (incl.
your OWN explanations), may build my own from plans (esp. the Spanish site),
have any good suggestions on a d.i.y. meter (does it have to be a 50 ua meter, etc.)?
Since the esr meter use microcontroller ic i suggest that you buy a kitset than building it yourself because we can’t get the ic from any local electronic shop. I’m not sure about the analog meter (50 ua), what is the range it can check?
I still, however, need data on the diode FMLM02S, because it may be blown (from some Sanken parts that look like it, it appears to be an ultra fast recovery (dual?) diode). As I said, it has 3 pins, and measures 0 ohms (diode function test
on DMM) between pins 1 & 2, normal diode test between pins 2 & 3. This part IS in the power supply section. Could it be that a failing e-cap caused this? If you can provide me with details of this part (I can’t find a service manual/schematic for the
unit ANYWHERE), sure would appreciate it. Haven’t checked anywhere else outside the power supply circuits yet on this unit. If you know of any other good, solid links where I can get data on this part, etc., please let me know.
Sorry Chris, no information on this part. The part can fail by itself or cause by a failing e-cap too. This diode is call as Schottky diode.
Jestine
http://www.JestineYong.com
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Hi Jestine Need yr help Problem Pincushion and horinzontal size cannot be adjusted monitor brand Samsung Sync Master 753DFX check all parts Okay need some tips TQ and God Bless
Hi Lim,
Have you change the h/v oscillator? Have you check the modulation diode and its corresponding circuitry? What voltage did you get at the collector pin of the pincushion transistor? It should have some voltage there and if you get zero voltage the pincushion problem will arise.
Jestine
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Dear sir,
Warm greetings!
I am an electronic enthusiast but I am really familiar with LCD, that is why I’ve purchase your LCD Repair Monitor. I have a Samsung Syncmaster 940N that has a problem. When I turn it on, it turns off after 1 second, press the power button and turn on again but truns off again after 1 second. If you can provide me the circuit diagram for this, I would appreciate it. If you can tell me the exact problem of this, I will post a 100% satisfaction on your website.
Thank you for your help.
Regards,
Hi Gary,
When the power is off (power LED doesn’t lit) may i know do you still get output voltages from the power supply. If you still get the voltages then chances is high the Mainboard may have problem. Make sure all the respective voltages are reaching the Mainboard before you conclude the Mainboard have problem. I have came across few with Mainboard problem.
Jestine
http://www.JestineYong.com
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Hi Jestine,
I want to ask you one question, what is the differant between plasma TV and LCD TV can you give me the info in detail?
Thanks
Hi Nd,
Try this link;
http://hometheater.about.com/od/lcdtvfaqs/f/lcdfaq2.htm
Jestine
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Hello jestine….i have a grundig 28wka 28wf100 flat screen tv,when it is switched on all that happens is the green light flickers very fast and no picture.any ideas what could be wrong with it.
Malcolm
Hi Malcolm,
If it flicker very fast it could be something had shorted inside. But before that do you get a steady supply voltage to the Mainboard/MCU IC? If yes then most probably the problem is in the mainboard. If not then check on the filter cap of smps with esr meter. Hope this helps!
Jestine
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Have a good day. Im now four years in servicing of any types of electornics devices but then i am very thankful for your always giving and sending me a tips in electronic repairs. Once again thank you so much and keep up the good work.
God Bless You…
S.B.E
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Hello mr. yong
I have a hp f2105 lcd monitor that the lamps turn off after a few seconds at power up.
power up again aand the same thing happens.changed the inverter board and the same thing happens. on one of the web forums a user stated he changed inverter, power supply and main board and still has the same problem. any ideas how to fix this problem.
Hi Thomas,
Check on the backlight as bad backlight could cause the lamp to turn off after few seconds.
Jestine
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Hi Jestine,
I know I read an article somewhere about a universal remote control that is capable of being programmed or used to control any TV and is great especially when the original remote control is lost. I read the ad somewhere and clipped it out, but I cannot locate it when I need it. So, I am hoping perhaps you may have one of these universal remote controls or know where I can purchase one. As always, I appreciate your help and support.
Thank you for sending me the article regarding testing the photo isolators because I need a way of quickly checking them in the field rather than by replacement.
Have a great weekend!
Thank you for your help and support!
Best regards!!
Bob
Hi Bob,
Try this link:
http://shopping.yahoo.com/s:Remote%20Controls:4168-Brand=Universal%20Remote%20Control
and
http://www.ehow.com/video_2280331_where-buy-universal-remote-control.html
Have a good day!
Jestine
http://www.JestineYong.com
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Hi ! Jestine
I need some help from you. I am just back from the
Thank you
Regards & Best Wishes
Martin
HI Martin,
Yes you can replace the transformer but you must know the secondary output voltages and the ampere too. I suggest that you get a stepdown transformer as most of the equipment can support 50/60 hz which is not a problem.
Jestine
http://www.JestineYong.com
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Hello sir
I’m so greatful to you for your effort to upgrade my ideas on electronics.I’m so fortunate that this month news letter coincide with my present problem i’m undertaking on one 21″ CRT monitor which has to do with no rasta or colour on the screen but the screen light up and when you regulate the flyback’s screen and focus the screen bright and dims but no colour and the remote not activated,
I need your help sir,
thanks.
Gibril.
HI Gibril,
If the problem is no character then you have to check the supply voltage to the video pre-amp ic. if possible use a scope to trace from the vga line to video preamp to vidoe driver ic and then to the RGB pins of the CRT board.
Jestine
http://www.JestineYong.com
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Good day! my friend gave me your e-mail add. I just want to ask some help on how I will repair my computer monitor? The display of the monitor is not clear or blurred, the color of the monitor is red and the signal or the display is not stable.
It could be the fault of a bad flyback, pctube and also bad parts in the crt area (red circuit) or even in the red signal line.
And there are times when the display is not stable the display window is in the upper most part of the monitor where you can’t see the display clearly just blue screen on the center and bottom part. How can I fix this?
From you description it seems that there are dry joints in the vertical section. You need to apply fresh solder into the ic pins.
I have another computer monitor which do not have power. Is there damaged component on this or just lose contact?
This you have to check it out because it could be bad components and also dry joints.
Best Regards,
Jestine
http://www.JestineYong.com
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hi
gud day a head lately iam confuse about the monitor i fix! i thought i can managed it already but i admitted my knowledge is not enough! the monitor i fix the display it has a horizontal line on display din i open the monitor i notice their are some break diode! but then i test it by using the multitester by testing the resistance of the diode pointer of the tester is moving! then i search for the diode on electronics shop but their no available! can i use the old one in junk monitor? hope you can give me a much effective way to resolve my problem! more power on you! hoping for your reply!
Hi nazer,
Yes you can use old diode from junk monitor but make sure it has the same part number or the spec is higher than the original one. Check fro dry joints in the vertical ic and if possible try replace the vertical ic and retest again. Hope this helps!
Jestine
http://www.JestineYong.com
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Which components to test if the t v is damaged by lightning?
There are many components that you have to check like fuse, bridge rectifier, power ic, power fet, circuit track (broken track) and etc.
Jestine
http://www.JestineYong.com
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Hi,
Thank you so much for your info on Electronic repair guide. I have questions about digital frame picture, it is Smartparts sp1100w. The problem is when turned on the power and the picture show very dim and only white screen shown. I have included a picture which shown in side it. What could cause the problem like that? Do you have any suggestions
or ideas please let me know. I would appreciate your input. Here is the link for that Digital Picture Frame.
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3829496&Sku=W222-1026
Thanks,
Hung
Hi Hung,
Normally a white display suggest that there is a problem with the cable connection between the mainboard and the lcd controller board but most of the time it was the lcd panel fault. If you could see some dim picture this suggest that the problem is in the back light. Hope this helps!
Jestine
http://www.JestineYong.com
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My name is Martin, I’ve recently started learning how to repair computers, monitors, tvs, integrated circuit boards, etc… I’ve bought several of your online downloadable pdf files, which have been very instructional, helpful and insightful.
Thanks for the support!
My question to you is, I’m looking into buying a Oscilloscope, but there are so many out there. Some are for repairing vehicles, hospital equipment and so on. Is there a specific make and model of Oscilloscope you would recommend for what I’m trying to do,
In fact you can ask the seller for the scope use in repairing purposes. It has many brands in the market like goldstar, textronix, hp, kenwood and etc. get one that has 100 mhz analog scope. If you have the budget you can try a digital scope too. The best description is to search for scope in ebay so that you will have more knowledge about oscilloscope.
and is there any additional tools that you think might be helpful in this new trade I’m trying to learn. Any tips you could give me, would be greatly appreciated.
Additional tools for your field are ESR meter and Blue Ring Tester. If you have some extra you may have to get a high voltage probe too.
Hope this helps!
Jestine
http://www.JestineYong.com
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Modulation Diode UF5408 they don’t have will IN5408 be use as substistute?
TQ Good-night and God bless.
Hi L,
UF5408 is a ultra fast recovery diode that have the speed about 75ns. 1N5408 is a general purpose diode and not suitable as substitute.
Jestine
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hi there, i know this may be a long shot but here we go. ive got a 19″ flat screen hewlett packard monitor (2004) its recently became faulty. ive stripped the unit down to find the faulty part. its a foxconn board- the only numbers i can see are 19.1823.01 rev:6 the top of the board it has sk in a circle then 76voa 94v-0. on the back of the board it has a sticker with a bar code then t151011.00 1425642-05
the faulty part on this board is a 3 legged transister with the code c5706 4f printed on it . any help n tracking this part down would be muchly appreciated. thanx paul
Hi Paul,
Try this link:
http://www.bluestar-online.com/SearchResults.asp?Search=c5706&Search.x=0&Search.y=0
Jestine
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How are you?
I’m fine thank you.
We have a problem with a 2 dimensional car dvd player which has a white screen. We have tested all the fuses, and all the connections, and everything came out good. We have also tested the capacitors and they seem ok. The car dvd has an av out, and when connected to an external monitor it works fine.
Basically, we have tried all the solutions for the white screen problem except for solution number 2 (in the ebook)
because we do not have the right tools for solution number 2. What else can be the problem?
And also, there are three PCB’s. One where the power supply comes into, the second is connected to the power supply and also connects to the dvd reader and the screen, and there is also a PCB behind the screen itself, IN which one of these should the problem be?
If all of the connections are good, voltages are good then suspect is the lcd panel fault. Make sure there is voltage at the lcd panel otherwise there would be white screen. This white screen problem are quite common in lcd monitor and the cause was a bad lcd panel.
Best regards,
Jestine
http://www.JestineYong.com
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I have a HP L1955 monitor i need a lil help with not sure if it is the inverter/power supply or the back lights when its plugged in green light is on and if i use a flash light and push the menu button i can see the menu options
It could be inverter problem that shutdown the display or it could be a bad backlight that shutdown the lcd monitor.Make sure the backlight connector is producing high ac voltage. If no high ac voltage the display will shutdown.
Jestine
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Dear Jestine Yong,
I am very pleased to receive you e-mail. I have a problem that my Laptop LCD Screeen is Half Black and Half visible.
What happened i don’t know. Please tell me its solution.What is its technical fault.
Very Thanks
Hi K,
It could be the lcd panel fault.
Jestine
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hi gud day as you read this! tnx a lot for information you give at me! can ask one more question! can you show me the vertical ic image! pls more power on you! it help me a lot in my work! hope you reply soon !
tnx!
Hi nazer,
Vertical ic usually have 7 to 10 over pins and is standing and attach to a heatsink. You can write down the part number and then find the data from the internet to confirm whether it is a vertical ic or not.
Jestine
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hi many thanks for all the information given i love working with these things but some time things just keep going wrong may this time and with you information things may change .I am trying to fix a tft monitor which was thrown away modle benq Q7c3 i could do with some halpe the problem is no power plag ok 240v ok rectifier ok that is as fur as i got for now becoues i spand alot of time working .I look for word to hear from you many many thanks fpr evry .
Hi G,
First check if the power ic is receiving dc voltage or not. If yes then check to see if there is voltage at the secondary side or not. If no voltage then suspect either the power ic is bad or its corresponding components have problem. Hope this helps!
Jestine
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I have search else where for UF5408, by the way Jestine i just a dell 17″ monitor Model D77i with problem : start up flickering sound then picture shaking then black out. Next start up Ozone smell from flyback no picture just black screen, tested capacitor in FBTover 90nf could it be the FLYBACK failure? If it is do U do the furnishing the FBT and how much is the cost? TQ God Bless.
Yes it could be the flyback problem because the value should not go up high till 90nf. Try use analog meter set to X10 Kohm to check again. The pointer os the meter should not show any shorted reading. I have stopped refurbishing for customers due to that at the moment i do not have the stock for the internal capacitor.
jestine
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Hi Bailing,
Here are the photos describing the other two probe tips, bought from
I guess is for convenience purposes when you want to poke into the anode cap.
Another monitor which I now am working on too is LG Studioworks 520Si. Actually I had asked you about this monitor when I first saw your website in March last year, but at that time I had no other tools, I’d only got analogue multimeter at that time, so I postpone diagnosing the problem.
This CRT monitor has problem of intermittent tick tick sound, when there is a tick sound coming up, the display also disappears for a short period. In your reply, you recommends to measure the internal capacitance of the FBT. Today I took the measurement and I only got 63pF, then I desolder it out and took it to ask other repairman where I could get the spare. The repairman that I know says that it’s not worth it to buy it, because firstly it is now hard to find, and secondly the price is too expensive to charge the customer. When I desolder the FBT out, I also desolder out the brown cable from the mainboard ( designated as S+ and S-) because this cable has two turns at the core of the FBT. I forgot to make a mark which point is the S+ and which is the S-.
After soldering the FBT back into its place, and solder some bad joints on the CRT board, and assembling the monitor back, when I power it on, there was no display at all. I could only see the power led on the right and the function leds on the left, lit like a flip flop ( it take turns / alternating ). I had done the assembling back very cautiously, but this seems like I am doing big mistake. Do you know what was causing it? Could it be caused by me soldering the wrong place between S+ and S-. What is the use of this brown cable?
I guess you have to double check again. Another name for the brown cable is sync cable. The function is to synchronize the smps because the flyback and the smps have to run in the same frequency. If you connected the brown cable other way round it won’t cause no display except that the display will wavy. From your description, yes the internal capacitor of the flyback have problem.
Jestine
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Hello Mr Yong,
Thank you for the free info on SMPS I am a service technician working for an LG Electronics service agency in
I have an N6 in Electrical Engineering, im 26 yrs old and have been a technician for 6 and half yrs. I totally related to your letter on having alot of theoretical knoweldge, but little experience in practical. My biggest problem is that I’ve been repairing Hi-fi, DVD, Projector and Amplifier for +6yrs and no TV.LCD, CRT. My boss wants me to move to TV, BUT I don’t have the confidence, can your material help me to become well equipped and become a successful TV technician?
Mark.
Hi Mark,
Thanks for your email and nice to know about your background in electronic repair. My material covers only the testing electronic components and LCD Monitor repair thus it will not suit you in the tv repair field. I suggest you to buy books from amazon and look for the author Homer L Davidson “Troubleshooting and Repairing Solid State TVs”
Best regards,
jestine
http://www.JestineYong.com
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Please help me to locate the best tutorials on the following.
tv compartments / sections on circuit board.
primery and secondary.
horizontal and verticle.
Get the tv repair book from amazon by Homer L Davidson “Troubleshooting and repairing solid state TVs”
please let me know what component is this (bridge rectifier )
STR
F6656
This is a power IC and not bridge rectifier.
Jestine
http://www.TestingElectronicComponents.com
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The GTC monitor while connected to computer A, the display color is normal; but when connected to other computer, the display has rainbow color. Do you know why this happens?
Did you shift the Monitor or the cpu? If it still has the same problem try check the posistor/degaussing area for dry joints.
If any FBT has arcing problem, could we see the trace/mark on the surface of the FBT, especially if the FBT’s color is white? Just to make sure the arcing has happened.
Yes you can see the tiny crack and the mark too.
Below the belly of the picture tube of GTC monitor I see a transistor coded as KAY 1705, but I couldn’t find the datasheet on the net, do you the exact part number?
Sorry some manufacturer have their own code which we would not know unless the manufacturer release out the information. You have to test it out and see if it is a fet, scr, npn, pnp or etc
On the neck of the picture tube I see the magnet rings are fixed with some kind of silicone grease which is still “wet” now after years of usage. Do you think this is normal?
It is abnormal.
Also, beneath the yoke assembly I see a blue resin coated capacitor with a red and a black cable which are already cut out. Do you know what is the original use of the cable?
Could you take the photo? Do you mean that the Monitor is working even with the cable cut?
What does the deflection yoke consist of, besides of course the coil turns? Does it have a board inside to put all the components?
Inside the yoke coil only the coil turns and ferrite core/magnet.
Jestine
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10 Comments
Leave a Reply
ko myat moe,Myanmar
February 16, 2009 at 10:19 am
Which transistor can be replace K2843 at 15 volt power supply 1.5Ampere
admin
February 16, 2009 at 6:01 pm
Hi Ko,
According to my data book the K2843 can be replace with K2645. Hope this helps!
Jestine
John Perry
March 29, 2009 at 11:23 am
Jestine,
HP f1903 LCD Monitor. I am referring to the post by Paul about the Foxconn 19.1823.01 Back Light board on an HP f1903 LCD monitor. My monitor went all black last night. I found a cold solder joint on the rectangular shaped capacitor between the two C57076 transistors, re-soldered it back to the board. Put the monitor back together and when I cycled the power to the monitor I was able to view the desktop screen only for a moment before it went back to black again. Upon reading the post by Paul on your web site I bent back a transistor and then noticed leakage from one C5706, looks like the loose capacitor took out that transistor. The Foxconn board appears to have twin power supplies and it will not operate with one damaged. I went to bluestar-online.com to order 4 but it was over $22.00 after minimum order price and shipping, so, I found them on eBay for $1.00 each and $4.98 shipping, used Buy It Now, THANK YOU for the information on your web site, it saved me from having to buy another monitor.
John Perry in California
admin
March 30, 2009 at 11:12 pm
Hi John,
You are welcome and thanks for sharing out your success. Have a blessed day!
Jestine
Joseph
January 2, 2010 at 5:47 am
Hi jestine and happy new year. what is the problem of a tv that has no rasta on the screen please ?
admin
January 4, 2010 at 10:22 am
HI Joseph,
Happy New Year! No raster could be cause by no high voltage or even no G2 voltage. The flyback must produce high voltage in order to generate the G2 voltage of about 250 to 300 VDC.
Jestine
Lee S.Lanois
February 3, 2011 at 2:01 pm
Mr Yong, I have (2) Smart Parts SP1100W digital picture frames with failed back light. Card assembly CPWBX0043TPZZ. May be European made. Turns up on Google search as used in Panasonic 11.5" PN-119D. Panasonic says not their product. Need to know sustitute/replacement component for repair
Thanks Lee
admin
February 3, 2011 at 9:53 pm
HI Lee,
I have no repair any of this equipment before thus i do not know what is the exact spec of the backlight. I suggest that you visit the website below to ask for more information:
https://www.jestineyong.com/?p=2543
Jestine
hardwareman25
September 24, 2011 at 3:32 pm
I urgently need support and troubleshooting guide on HP F2105 21'inch monitor which switches itself automatically to sleep mode in 2 minutes. It wont show anything again until you turn it off and on again.
admin
September 26, 2011 at 2:21 am
Hi,
Check to see if the B+ voltage is too high causing it to shutdown. It could be flyback problem:
http://www.electronicrepairguide.com/testing-flyback-transformer.html
Jestine