Came across no power problem in this Samsung 510Bn LCD Monitor. Found only one of the secondary diode shorted with the part number of SB5H100. This diode is a high voltage schottky diode and have a rating of 5 ampere with 100 Volt. Since i could not get this diode from my local electronic supplier, i try out another replacement number just to test it out. The part number was UF5404 with a rating of 3A ampere 400 Volt 50 ns and i use this part number in many CRT Monitor repair and found it to be very reliable. I knew the specification is lower then the original one but it worth the time to just test it out.
After the replacement and many days of burn-in test i conclude that this ultra fast recovery diode UF5404 can be use to substitute for SB5H100 and i believe it could also be use in any other 15″ LCD Monitor. If you could get the original part (SB5H100) please let me know by posting at the comment below. For those of you who want the datasheet for SB5H100 and SB5H90 then please click here for more information.
Last week both of my students attended the Basic Monitor repair course and these three days they have completed the Advanced Monitor repair course. Starting tomorrow onward i will be putting them into my technical department to repair customer Monitors with the guidance from my technical staff. With the actual faults they would be trained on how to use the best way to solve a particular problem. Generally i would let them try on their own first before any help given to them so that they will be independent and this is all i want from them.
What if after the training and they start to repair at their own place and i’m not there by his side to guide him? Meaning one has to know what they are doing, how to diagnose the fault and how to provide a solution after the training. Once they grasp hold of the repairing techniques during the training in the technical department, it would be easy for them in the future even if I’m not around by his side. Both of them will be taking the LCD Monitor repair course in two to three months time to complete all the repair courses offered by Noahtech. Here are the photos and videos taken during the 3 days Advanced Monitor repairing course :
Ever wander what is the type of oil leaked from the electrolyte capacitor? After few years in service some cheap electrolytic capacitor begin to bulge and some have the electrolyte leaked from bottom and this electrolyte could destroy the corresponding circuit or components. Even in some branded electrolytic capacitor that have a rating of 105 degree celcius could also give problem especially in the environment that have less or no ventilation in many older HP laser jet printers. The power supply of the HP laser jet was totally covered and these e-caps problem were mainly electrolyte leaked . Many times, replacing and cleaning the power board after repair solved the no power problem in laser jet switch mode power supplies.
Here is a definition of electrolyte:
The electrolyte is usually boric acid or sodium borate in aqueous solution together with various sugars or ethylene glycol which are added to retard evaporation. Getting a suitable balance between chemical stability and low internal electrical resistance is very tricky and in fact, the exact composition of high-performance electrolyte is a closely guarded trade secret. It took many years of painstaking research before reliable devices were developed.
Electrolytes may be toxic or corrosive. Working with the electrolyte requires safe working practice and appropriate protective equipment such as gloves and safety glasses. Some very old tantalum electrolytics, often called “Wet-slug”, contain corrosive sulfuric acid, however most of these are no longer in service due to corrosion.
Recently one of my friend who work in the maintenance field sent me a switch mode power supply board for repair. This SMPS board comes with a control board for controlling display. The complain was no power and the fuse blown into a very dark color. There must be some components that had developed a direct short circuit that could have cause the fuse to turn into black and by replacing the fuse only will not solve the problem. My next step was actually to use a series light bulb trick but have decided to just scan from above to see if there is any visual indication of components blown. Scanning from above i could see the varistor have some problem. After taken out the part and check with ohmmeter and found that it was totally shorted.
As usual one have to check for any corresponding parts first before you put back a new component and power On it. I have tested the bridge rectifier, power fet and check the big filter capacitor and components in the EMI filter circuit and found all of the components to be good. Conclusion, this switch mode power supply problem was caused by only a shorted varistor and a blown fuse. The indicators (LED’s) in the controller board lit proof that the power supply was working fine upon power On.
If you have read my previous post about getting the TIP3055 as substitution, i guess you have to put on hold for this replacement. Read from this member feedback about using the TIP3055 as substitution for C5707 transistor
“The TIP3055 is not a safe subsitute for the 2sc5707. It will work, but runs extremely hot, and will eventually catch fire unless adequately cooled in the vast majority of CCFL inverter circuits that it will operate in. There’s a reason why cheap general purpose transistors don’t wind up being used in place of specialised models, and it’s reasonable to say that “fire hazard” is one of them!”
Since he already tested on this transistor, i guess the best for you is still to get the original part number. If you would like to order online for this C5707 transistor then please visit Bluestar Online dot com.
I got lots of emails asked about the substitution part number for C5707 transistor that were used in many LCD Monitors. I normally asked them to buy online as original part number is still the best part for replacement as it is not easy to get a replacement for this transistor. For your information if you have the C5706 transistors you can replace it with C5707 and i have tested it and the LCD Monitor worked perfectly okay. To some that can’t order the parts online and can’t get it from local electronic suppliers, in fact you can try this part number as replacement.
Try use TIP3055 transistor as recently i came across a website that says that it can be use for replacement for C5707. The TIP3055 is bigger in size compare to C5707 but with some adjustment you could easily fit into the board. However i haven’t try it before because i could get the C5707 from the local market. Try it and please let me know about the result. By the way you can download the C5707 transistor data or specification from this website-please click HERE.
If you love electronic repair whether you are in full time or part time repair then you must keep some spare parts to speed up your repair work. Sometimes it might only takes you a very short time to locate the fault but it may take you hours to get the spare parts from the electronic supplier shop. It is not economical every time when you found a bad component and you need to go to the center of town just to buy that component. If it is a common component then i suggest that you keep some for future use. Keep some fuses, resistors, capacitors, transistors and diodes could save up some of your time in electronic repair. Another thing that you have to keep is junk electronic board.
Sometimes there are certain components that we can’t get from electronic suppliers. If you are in the Monitor repair you would know that many local electronic suppliers does not sell CRT tube, SMPS transformer, flyback transformer, B+ coil, some power IC or even latest color IC and H/V oscillator IC. The best is to salvage from the used boards. Although there were times we could not get the main parts that we want from the used boards at least it could help in getting some of the secondary parts like capacitors, diodes, transistors and etc. If you have some extra do keep some common parts as with this way it would speed up and complete your repair job fast.
The Cameron Highlands trip was good and we have enjoyed every moment there. The last time i went there was two and a half years ago. The temperature at the hill there was about 18 to 20 degree celcius and the place is famous for its plantations (fruits and vegetables) and Singapore import lots of fruits and vegetables from there too. It took us about 3 hours and 45 minutes to reach Cameron Highlands from KL. During the few days in Cameron Highlands we went to many farms like the cactus farm, butterfly farm, Strawberry farm, Bee farm, Kea Farm (bought some fruits and vegetables to make juices) and lastly the Bahrat Tea Plantation at Cameron Valley. We ate durians, enjoyed steamboat dinner and western food too and went to night market and bought lots of fresh vegetables and brought it home.
In the middle of the night of course me and my friend watched the Olympic Games too while the kids played Game boy. I saw how Usain Bolt from Jamaica ran like lightning and broke the 4 X 100 Meters world record! He broke the 100 and the 200 meters world record before that. It was superb fast! Overall, my family and my friend’s family were truly enjoyed about this fantastic trip. By the way please give me sometimes to respond to your emails as i got lots of them in my in box. Here are the photos and video shots taken during the three days at Cameron Highlands.
Tomorrow morning my family will be going to Cameron Highlands for holidays. We will be going with my friend’s family. This friend of mine and his family were the one that joined me and my family during the Langkawi trip back in early June this year. This week in fact is a school holiday and is about the time to bring my kids and wife to enjoy the nature at Cameron Highlands. I could relax too after given so many repair courses for the past many weeks. Recharge the body and mind so that i could continue to give the best to my company. I hope i could find some internet cafe there so that i can continue to check my emails and provide support to my members. If I’m late in responding your email, please forgive me and once I’m back i will reply to you as soon as possible. As usual, after the trip i will show you some of the photos and videos for you to enjoy.
By the way, just completed the three days repair course for a participant from Petronas. He was kind of a unique student and performed very well during the course. He asked lots of repair questions and he really write down all the answers. He seems to be different from others in term of communication and thinking and I’m very impressed by the way he shared some of his plans to me. He even carefully redraw all the diagrams that I’ve given him so that with this way he could ask me questions whenever he come across any circuits that he doesn’t understand. He even brought along his Fluke 189 True RMS MultiMeter for testing purposes and you could see it from the photo below.
I have used that meter for some testing and very satisfied with the performance. By giving courses, i could have the opportunity to meet up many peoples from different races and its good to hear some sharing (whether in electronics or some other topics) from fellow participants too. Next week there will be another class for the Advanced Monitor Repairing course and thank God for all His wonderful blessing towards me, my family and my company. All glory be unto Him!
