The DELL E151FP LCD came in with no power symptom and upon opening up the cover I saw few components that were burnt. R623 (4.7 ohm) burnt at the side and you could still recognized the resistor colour code. The current sense resistance (0.68 ohm) outer layer part had came off and slightly burnt and also the filter capacitance C605 (68uf 400v) one in every of the pins had became rusted and came off after I tried to desolder the pin.
This is not a brand new model and that i believe various intimate techs had solved the matter. But for those who haven’t come across this problem, you may use the procedure to troubleshoot and repair any other type of LCD with power problem.
I will 1st take away the facility electrical device and make certain it rings okay with dick smith flyback tester. I try this 1st as a result of I don’t need to waste my time checking alternative parts and later solely seen that the facility electrical device is that the caused of the power problem.
Once it rings okay i’ll live all the secondary diode. For your information most LCD power supply widely used the dual schottky type diodes and the specification usually in the 10 to 20 amp with about 40 volts. However I do bump into some designed square measure still uses the immoderate quick recovery sort diodes within the secondary section. Make sure you recognize a way to check a traditional diode and a schottky diode.
Once I confirmed that the secondary aspect parts square measure all tested okay, i’d then proceed to get rid of all the parts within the primary aspect. Some parts within the primary aspect you’ll be able to check on board just like the bridge rectifier and fuse.
If you are new in LCD repair lg tv repair london would suggest you to check all components off board (with a lead removed from board). With this way you will be sure that all components that you have scanned through are okay. These square measure the parts that I found defective; fuse-2A, R615-0.68 ohm, R613- 1K, R612-47 ohm, R623-4.7ohm, D604-1N4148, Q601- SSS6N60A, C605-68UF 400V and IC601-UC3842B.
Total was 9 parts and it took American state but twenty minutes to ascertain all the parts in primary aspect. Now is the time to search for spare parts. After disbursement regarding five minutes within the component compartment I managed to seek out all parts except the facility junction transistor SSS6N60A.
Though this half variety is generally employed in switch mode power offer, my electronic supplier does not have this in stock. I would then browse through the semiconductor data book to search for equivalent part number.
After all the new components have put into their original place or location and of course with the power transformer soldered, I don’t immediately switch on the power supply. I would 1st use a 100watt light-weight bulb connected asynchronous with the live line.
The best place to place the sunshine bulb is that the fuse holder space. Remove one in every of the fuse lead and connect the sunshine bulb across it. Power it on and start to look at the bulb.
If it brightly lit and stays that way for couples of minutes then there is still problem in the power supply. However, if the bulb doesn’t light-weight in any respect then this can be a decent sign that the facility offer is also operating.
Use a multimeter (analogue or digital meter) to place the red probe at the centre pin of the Schottky diode (and black probe to cold ground) and switch “On” the power. If you get some correct voltage reading from the outputs and also the bulb doesn’t light-weight in any respect, then this confirmed that the power supply is working.
Switch off the facility offer and connect back the fuse and switch the LCD “On” once more. I’m very sure the LCD will now work. Assuming the output Schottky diodes are stand alone type (normal ultra fast recovery diode) then you need to place your red probe to the cathode and black probe to cold ground.
Whether you are troubleshooting the DELL E151FP LCD or other brands, you can always use the procedure given above to repair the power supply problem.
This technique are often even use to repair alternative varieties of power offer too. No matter what varieties of power offer you’re troubleshooting, simply make certain you recognize a way to check and check the fundamental electronic parts.
If you ever missed one, sad to say you would not be able to solve the problem or it might just take you many of your precious hours to complete the job. Happy hunting!