Within the above case, after the cover was removed, the initial thing I check was your vcc (supply voltage) to the inverter IC. This model is using the famous TL1451ACN Pulse width modulation (PWM) IC-some preferred to call it as inverter IC. Pin 9 is the VCC supply input and it should have about 12 Volts when the ability is “on”. Measuring the pin with my faithful digital multimeter, it scans only about 3 volts which indicates there’s a problem in the supply line. It could be components that are faulty that dragged down the line or it could be the change mode power supply itself that don’t produce enough power.
In order to find the answer as which section is offering problem, the first clue was that the strength DIRECTED indicator lit and also this show that the IC is supplying enough power to the circuit. Another idea is that the meter is registering about 16 volts at the input of the 2A fuse. Because of these clear solutions, we can conclude that the switch mode strength supply is working fine. You can also use a 12 volt light bulb to confirm it. You may read my other post on samsung tv repair merstham articles which discusses using 12 volt bulb for troubleshooting purposes.
I kept on asking myself, why the volt quality drop to three volts after the fuse. Prior to the merge it reads about sixteen volt but after the fuse it reads only 3 volts! I didn’t believe the fuse, because the fuse can only either yes or no and no in between. The first circuit that I examined was the start signal but all components checked out to be okay. I even desoldered the pin 9 of TL1451ACN inverter IC just to be sure it is not this IC that pulled throughout the volt quality.
This problem really challenges my troubleshooting and mending skill, because almost all suspected components already checked out to be working. Even the start circuit transistors (C945 & A733) We direct replaced, afraid they would breakdown when under load. The only part that I didn’t check was your fuse! By using my meter positioned across the fuse, rather than getting low ohms or no ohm reading I got one. 012 Kilo ohms! We have got a surprised and don’t think that a blend can actually go into high ohms rather than open circuit. I usually thought that a fuse will either be near or open circuit. A fuse with zero ohms turned into high ohm thus the 16 volts dropped to 3 v! I’ve came across lots of this type of blend but this is the very first time a fuse transformed into high resistance.
Changing the fuse only put the DELL E152Fpb LCD Monitor back to life. The lesson learned from here is the fact that don’t assume that a component is definitely in a good working condition. You have to confirm it with your meter and if you still suspect the component is giving problem, simply replace it with a known good one and retest the equipment. Semiconductors can breakdown when under full operating voltage.