Electronics Repair Questions/Answers and Testimonials- Part 47
I have found one DELL laptop where there is no display, but while connect to external monitor, display is ok. I have never worked with LCD/TFT monitor, but theoretically i know almost every details. One repair shop has rejected and told lcd screen is defective and it will cost Rs.4000 to repair. Should i take risk of that and how to start diagnosing.
It can be the problem of bad lcd panel or the inverter board. If there is totally no display even though you have used a high power torch light to shine on the screen then chances is very high the screen is the problem.
One ACER LCD monitor, which is also rejected, the problem is when start light is normal but after 5 to 10 minutes brightness is gradually increased too much. what may be the fault in this case.
First make sure the output voltages from the voltage regulators ics in the mainboard are good and stable. If the voltages are good then most probably the programs in the eeprom/flash rom could have been corrupted.
Hope this e-mail find you well.
I have a westpoint TV set that has a black picture with a one horizontal line (as shown in pic)
I am suspecting the problem is from the horizontal IC or a surrounding component.
What is your opinion? Thanks in advance for your time and help.
The problem is in the vertical output ic area. It can be dry joints, missing supply voltage, bad vertical output ic or even the vertical yoke coil already open circuit.
hi, Jestine how r u ; hope ur fine
dear sir my friend buy sony l.c.d klv -v40 a10. after few year lcd start probelum. sometime only colour thin vertical line on the screen and sometime it working fine and sometime full screen white. when it work fine i use remort controal to increase volume . Volume up but there is no sign of volume bar and no channal disply on the screen. kindly help me what,s the probelum and how i can fix it.and also tell me where the probelum come from. it come from Logic board or system board.
I’m fine thanks. Try check the LVDS cable between the T-con board and the mainboard. It could have been corroded. Check also the connection between the t-con board and the lcd panel.
I get a SAMSUNG 510 n 15 ” tft monitor.It has typical problem.The monitor restart in 1 sec .Already try to detach the LCD panel data cable .The inverter lamp on then off on then off automatically….I can understand the picture comming kok in the monitor.But
it is not stay it restart again and again….
It could be the MCU problem sending an on/off signal to the inverter ic. This model is famous for MCU program fault. Before that make sure the output voltages from the power supply are good and stable.
I have replaced the vertical output ic, and the TV was broguht back to life !
How are you I am fine and I am always pray for you please help me for solving this problem
I have a Philips 17″ Monitor problem is “No Input Video” & goes to Sleep mode” I will try my best
but not working and I am fade up. Please tell me what is the main reason.
I am waiting for your help.
Hi S Munawar,
Try check if the horizontal/vertical wire inside the cable got break or not. If ok then possibly the MCU or eeprom ic could have problem.
With regards to this blue ring tester their is “Misc Parts” place inside a small plastic pack what shall i do with it?
This is for you to wind the coil so that you can use the blue ring to test if your meter is working or not.
With regards to this blue esr/low ohms meter tester their is “for alignment and test” i think its a 2 pcs. resistor place inside a small plastic pack what shall i do with it?
This is for alignment purpose. Since you already bought the fully assembled kitset thus I have calibrated for you. You no longer have to use it at the moment. After few years in service and if you think the result from the meter is not accurate you can you these resistors to help recablibrate.
through your explanations, I had fixed several monitor,
I’m very grateful for your help and knowledge.
Have you seen this problem before? (Magnavox, but made by JVC).
The 12V output for the Drum motor is pulsating – you can hear the Drum speed up and down constanly. The voltage is pulsing between 11-7 and 11.3V, never stable.
The picture is there, but the color vibrates constantly. It cannot get in sync.
If I disconnect the drum motor flat cable, then the 11.7V is stable, but of course, the VCR shuts down.
I have replaced all the PSU capacitors – all of them were bad I replaced the Z15 diode, and the 3 rectifiers in parallel with it, off the transformer.
I have tried everything I know on the PSU circuit, but nothing gets it up to 12.3V, like I know on other models with the same circuit.
All other diodes, resistors, etc check out OK
The drum/motor is fine – Iput it in another JVC VCR, and it played fine.
Perhaps the transformer is bad?
Try direct replace the two opto ic as it could break down when under load. Check/replace IC5301 and check the resistor in the “NF” pin that leads to the opto PC5101.Keep me update on this.
Hi Jestine, i have a problem with logic CRT 54cm TV, the line voltage is too high, 130v instead of 110v, i am getting 10v from 6.2v zener diode connected through eeprom, eeprom changed but nothing happens. The TV uses 50q65rt ic in power supply, thank you sir.
Check the resistors around the secondary side of optoisolator ic. An increase in resistance value in resistor could cause such problem.
Dear Mr Yong
I had a printer that was not picking up paper, each time it pick up the
paper from its tray, it cause printer error led on. However It has no
problem printing one by one inserted into the front . Do you have came a
cross this problem before?
Try activate the paper sensor then do a test print without the universal tray. From there you can see if the pick up roller is rotating or not. If not then you have to check the solenoid. make sure no melted rubber sticks to the arms. By the way what printer and model is that?
also i am working on a crt tv with vertical problems where i replace the ictda9302h and also some capacitors but still have the same problem.i don’t know how to test all the 7 pins for voltage.need help thanks
download the schematic and check which pin is the supply voltage. Place your black probe to the chasis ground and the red probe to the supply pin (vcc). Missing supply voltage could cause one horizontal line.
oh thanx.the Lord.justine let me ask what causes vertical and
horizontal lines in lcd tv and monitors.and how can i solve this.give
technic please .thank.MAKALOS ELECTRONICS.MWANZA TANZANIA
It can be lcd panel or bad t-con board. Sometimes bad lvds cable from mainboard to t-con board also could cause such symptom. If the problem affected the OSD menu then the lcd panel is the problem.
We all give God praise. It is you we owe thanks for your selfless effort to humanity.
i have been achieving result with the blue esr meter on my laptop motherboard repairs since the last time you gave me clue on how to interpret the result. I have come to the conclusion that anyone who is doing repair work in electronics without esr meter has not yet started.
I know one can replace a lower voltage electrolyte capacitors with a higher voltage one
However I have a burnt polyester cap of 105K 250HT ( 1 MF 250v @ 10%) and cannot find replacement. Can I replace it with 154K 400JS. (0.15 MF 400 v @ 10%)
Will the capacitance affect circuit which is 0.15 MF.
It is for computer power supply
You can try. It all depends on the circuit.If the ciruit is too sensitive then the only answer is to get the same replacement otherwise you can use higher cap value and voltage.
I had my 14″ JVC crt tv 110Volts,and it appears like having color problem and sometimes the power is irregular…it will off/on .What particular electronic component do I need to replace? The normal standby color should be blue…but their is color green at bottom portion of screen.
Check for dry joints in the power side. Check for bad e-caps too.
Again ,thank you for the report you have shared because I have learned the basic electronic components…But there are some electronic parts that should be learned like for example IC . How to test IC using my Multimeter tester…
For ic the best is to use scope. Mutltimeter oly could check on the supply voltage. But then again it depends on what type of ic you want to test.
Transformer—how to test Transformers that were soldered in the circuit board…if I am going to desoldered it from the board and supply a power on it…where to place the line 1 and line 2 of 220volts power supply…There are 4 or 6 legs to choose assuming there’s no sign of INPUT or OUTPUT….some example you are desplaying is very common resistor (the color coded )
You need a blue ring tester to test transformer. Test on the primary winding. The filter cap positive pin and the power fet drain pin is the transformer primary winding.
How about those resistor like in the form of box with 4 legs or 6 legs…
Do you mean network resistors?
How about the ceramic color blue, black, green and red .what are these component and it seems not familiar in any books of electronic..?
Those are ceramic or dipped resin capacitor and you can test it using digital capacitor meter or insulation tester.
Hello, Mr. Yong. Thanks for your information about your new blog. I hope this will usefull for me.
By the way I have a problem with a “SONY” CRT old tv. The brightness of it can’t be adjust. so only blur I can see. When I opened the cover, I checked the flyback and other equipments. And then I want to adjust the screen under focus on the flyback. But likely there is no cable connected to the screen, so where is the screen control on the fly back really moved to?
Please, reply soon, Thank you
Blur or dim can be caused by low heater and g2 voltage or even bad picture tube. If the flyback does not have the control this means they are using software to control it through a circuit. You need to trace backward from the CRT board G2 pin and see where it goes.
Basically, what is the difference between ordinary CRT and Trinitron that makes it difficult to do such replacement of PCBs?
I found that the Trinitron tube internal design is different from the common tube thus making the overall design of the PCB board also different. It is not easy to repair Trinitron CRT Monitor as they have compact and complicated design and components.
I am facing one problem in samsung model no.740 lcd that display dull without contrast i have conform the problem the lcd pannel is faulty what will be the problem i suspect main ic on the lcd pannel.
please give guide line
with best regards
It could be the programs in the eeprom ic, the main lcd controller ic or surrounding components have problem mainly the small smd caps.
Is this correct or not :
On screen display is locked. Fix it by:
The OSD can be enabled or disabled by pressing and holding the Menu button on the front panel for 10 seconds. If the OSD is locked, the warning message OSD Lock displays for ten seconds.
* If the OSD is locked, press and hold the Menu button for 10 seconds to unlock the OSD.
* If the OSD is unlocked, press and hold the Menu button for 10 seconds to lock the OSD.
Yes but not applicable to all model. Samsung model you can press the menu.
HI; Jestine I would like to ask you, how i can identify the primary pins on the transformer.
Trace from the positive side of the big filter capacitor for the first pin and the other pin is from the center pin of power FET. These two pins are the primary winding.
Good day sir. Thanks to the lord you’re back. Sir jestine can you please help me solve the SMPS high b+ problem. The tv ISONIC blown the filter ecap 160v, 25v,& 35v when I check the b+ it is 150v and also the vertical IC is deffected. When I check the vcc of vertical ic is 35.58v. So I think I have a problem in SMPS high output voltage.
Yes the output voltages too high killing all the components. Does your tv use optoisolator ic? If yes then check for any resistors that had change the value in the secondary section of the opto ic.
Thanks for your news.
Your article was very helpful to me.
I wonder that the FET with different pin connection has been produced.
It is incredible. But it is necessary to admit the reality.
Waiting for your next news.
If it can happen to the Bipolar transistor then it can happen to FET too. Nowadays there are so many manufacturers and they don’t follow according to international standard anymore. If not because I have knowledge on electronics circuit (the base should not connect to the negative side) I guess until old age I still not be able to locate the fault due the different in pin configuration.
I dont understand G2 and G1 voltage sir please explain me i also check but i think some voltages are not stable
It is located at the CRT board. Some crt board have the marking on it. If it does not have the marking then you may need to test. G2 should have about 250 to 300vdc and G1 should have – 10 to – 100volt. and these voltages should be consistent and will not vary.
I need a little advice.I repaired a TV set which had STRW6553A for switching.I tried to look for its cross-reference on the internet and its datasheet,but could not find any.Since I don’t have databook, I used STRW6554 and it worked,but I am not for how long it wil last.
Sorry I do not have the datasheet. Since it is working now, then let it run longer. This replacement number is the same family number which means the spec of the STRW6554 higher than the STRW6553.
Hi Jestine,what kind of parts is in the picture?is it optoisolator?there’s 4 pin in the other side and 3 pin in tho other side,The resisto was also open,is there possibility theres more parts was affected?i found that in my Insignia TV.I open it because smokes came out when i switch on my TV..Hope you can help me..Thanks More power sir.. God bless always..
It is a power ic. Since the power ic already blown this means you need to check all the surrounding components and make sure they are good before you fix in the replacement parts. Replace the resistor as well.
I just did an interesting repair. I was given an LG 42LB1DR-UA; the owner said that it had not worked right since it was new (in 2007) and had been in for repair several times. He had decided to buy a new TV rather than spend more money on it and thought I would like it for the parts.
First thing I did was replace the bulging capacitors on the power supply board but that didn’t fix it. Since the relay clicked on and off in less than 2 seconds, I decided to check the inverter board (thanks to your book on LCD TV repair). It was a bit of work to get to, as it was located between the front screen and a back shield that held the power supply, main and input boards. Once I gained access, I found the connector to the inverter board was partially unplugged. Once plugged in, it came on and almost worked…it lit up okay but no video. I found that one of the flexi-circuit “cables” that linked the input board to the main board was intermittent. I repaired it with a pair of scissors, by trimming the end off of the contact strip.
It’s been working for about 3 weeks with no issues… This was a major score…it does HD, has a QAM tuner, several inputs, has a great picture and cost over $2000 when it was new! The only downside is that it weighs about 83 lbs (38 kg)…. I told the previous owner that I had found the problem and he wished me well and to enjoy the TV.
Thanks for the great book and your newsletter!
My dear Jestine,
Your new letters are so good that I have no express to say a word. They are really unmach & fantastic.
Your recent letter I found & was shocked by knowing that “A same part number for transistor could have different pins configuration” on DVD player 301K model. Is it true? I have some doubt on it, please clarify how it is possible.
Since only component’s number we are marked not manufacturer or brand name. It is also not possible to get same
component’s number match with (or found in local market ) the same brand name.
With regards & Love,
This is true as you have seen in the newsletter. Nowadays there are many manufacturers and they do not follow according to standard transistor marking anymore.
good day sir… i have new hot air station 850 c smd rework station. my problem is i have no idea in using the station. like the control the heat and air…please help. thanks ..God bless you.
It depends on the nozzle you are using and what type of components that you want to remove. For airflow only you can set to 450 c with 4 to 5 wind speed. To remove SMD ic you need to set to 450c with 6 to 7 windspeed. I suggest that you test on several junk board to familiar with this machine. You may also try search from YOUTUBE on how to use it.
The laptop not boot up once press power ON, but after 20-40 minit the laptop only boot and display the windows.
i already try connect to external monitor once power on, but the monitor can’t detect the signal.once the laptop boot and display window, then the external monitor just got the signal.
It may be the laptop or the power pack problem. First need to isolate the problem-is the power pack output supply good? How many voltage did you get from the power pack? If the power pack is good then the problem most likely in the Graphic chip where the ball joints underneath have dry joints.
Hello sir . Plz i have one MATSUI TV 1436XA . If i on this tv it have no raster only flybar line with high brit.
Check if the G1 or the G2 voltage is abnormal. Visit this link too:
Then i have one sharp tv 14G1-SMK2 i discover that HOT of this tv was shorted , then i remove it and i check the collector voltage it was 113V , i put another HOT their and i on it . It work but before 10 seconds it came over HEAT and it shorted again . I was change the flyback transf , booster cap. And does the same things . Plz help me out
Please visit this link:
good evening..I was always encountered a vertical line in a t.v set when repairing. I was checked all components in vertical section but the line still appeared. Is it on the chroma?
Vertical line problem you need to check on the horizontal circuit. Check from the horizontal yoke coil and the related area. It could be dry joint, bad horizontal coil or bad components.
I’m working on Samsung 15″ LCD Monitor 153V.
One second shut down problem, as you described at your LCD monitor ebook.
I found some bad caps and an open inductor coil (used blue ring tester) on the power supply.
But there is no part number of inductor coil.
How can I find same coil or Where can I buy same coil?
I attached a picture of coil that took out from power supply.
I don’t thnk the coil is bad. Have you checked it with ohm meter? The blue ring tester is for checking big coils and not small coils. Checking small coils will not produce any light in the tester. The shutdown problem can be caused by one of the backlights or the high voltage transformer have problem.
Hello My name is Nicolas i am from Cyprus . I am a domestic appliances technician. The past few years almost all the appliances are fully electronic .ofcourse this means that every each devise has one or more (ac/dc) electronic circuit board. Most of the time is the a problem on a device is the electronic board fault . What i want to is to be able to troubleshoot , diagnose , a printed electronic circuit board check the electronic part of it and if there is a problem to be able to repair it change a part if is needed and make it work as it used to be. i donr have experience on repairing electronics,with your books i will be Troubleshoot diagnose and repair any printed circuit board on any decice such as domeatic appliances.?
thank you.regards Nicolas
Yes you can but I cannot guarantee 100% because sometimes it depends on the individual itself, parts availability and etc. Having an electronics repair knowledge will be an added advantage to you. You can start to repair other electronic equipment beside the appliances. I suggest that you get the Testing Electronic Components ebook first. Once you are good in testing electronic components you can start to perform the electronics repair work. If you have other question please do email me again.
Im Fixing a monitor,
SYLVANIA 17″ Multi-scan color monitor,
and the problem is that a resistance has burned, and lost the color
code, and i have no way to know the value of this resistance.
In the circuit is the number R754.
This resistance have a value of 46 ohm, when measured with multimeter,
but i think this is wrong.
I need your help because right now have no internet access and have no
way to search the required information for this monitor
Can you send me the correct value of this resistance?
I address you, because you have been very kind and helpfull
Sorry I do not carry any schematic diagram thus I do not have the value. Try search from eserviceinfo.com. Sometimes it is hard to find the schematic because too many OEM brands in the market. You can also the compare the resistor with the other color circuit. If the red resistor value out you can compare the green or blue resistor value. RGB have the same color circuit.