Got this one in today, there is no power light.
No caps with bulging top. The 5V is fluctuating around 4.5~4.7V, the 12v reads steady at around 13V.
So the 5V is unstable and not good enough for the logic board to run. The 12v is showing steady due to no load, but if I put 1A load on it, then it fluctuates also.
Heat up the whole board with hair dryer, I use hair dryer to troubleshoot the board when I do not see any caps with bulging tops, while monitoring the 5V, after a few minutes of heat, the 5V become stable at 5V and now the monitor will power up and works OK again.
Then I use cold spray the startup cap in the primary side, the unit shut down and the 5v becomes unstable again, replace that cap. The cap has ESR of around 3 Ohms when cold, drops down to about 1/2 Ohm after heat up.
I also recap the board.
No caps with bulging top. The 5V is fluctuating around 4.5~4.7V, the 12v reads steady at around 13V.
So the 5V is unstable and not good enough for the logic board to run. The 12v is showing steady due to no load, but if I put 1A load on it, then it fluctuates also.
Heat up the whole board with hair dryer, I use hair dryer to troubleshoot the board when I do not see any caps with bulging tops, while monitoring the 5V, after a few minutes of heat, the 5V become stable at 5V and now the monitor will power up and works OK again.
Then I use cold spray the startup cap in the primary side, the unit shut down and the 5v becomes unstable again, replace that cap. The cap has ESR of around 3 Ohms when cold, drops down to about 1/2 Ohm after heat up.
I also recap the board.
Attached Files