Is it my monitor or my power brick that's broken?
June 11, 2009 1:18 AM Subscribe
Is it my monitor or my power brick that's broken?
Recently my Fujitsu Siemens S20-1W started acting up. When powering up the PC the monitor stopped detecting that it was supposed to switch on - I would have to power it off and on again from the front panel. After a week or so of this behaviour, it simply stopped powering on at all.
We noticed that the light on the power brick was out, so I disconnected the brick from the monitor, and swapped the kettle lead for a different one. While the brick was not connected to the screen, the light was on. As soon as we reconnected it, the light on the brick went out, and still the monitor would not turn on. We tried this with two other kettle leads (we have like a million lying around) and it would be the same each time: plug the kettle lead into the brick and it would light up, but it would stop working as soon as we connected the brick to the screen, and would never work with that kettle lead again.
Fujitsu-Siemens' support line won't help: it's out of warranty; they recommend I get it repaired locally. If I can't fix it myself, I'd like to have a fair idea of where the problem lies if I do have to take it to a professional. I'm reluctant to just go to Maplin and buy a new power brick in case the monitor kills it.
(The problem coincided with my planning to buy a larger screen, so I don't need it fixed immediately, but it's a very nice screen and it would be nice to pass it on to my partner.)
Recently my Fujitsu Siemens S20-1W started acting up. When powering up the PC the monitor stopped detecting that it was supposed to switch on - I would have to power it off and on again from the front panel. After a week or so of this behaviour, it simply stopped powering on at all.
We noticed that the light on the power brick was out, so I disconnected the brick from the monitor, and swapped the kettle lead for a different one. While the brick was not connected to the screen, the light was on. As soon as we reconnected it, the light on the brick went out, and still the monitor would not turn on. We tried this with two other kettle leads (we have like a million lying around) and it would be the same each time: plug the kettle lead into the brick and it would light up, but it would stop working as soon as we connected the brick to the screen, and would never work with that kettle lead again.
Fujitsu-Siemens' support line won't help: it's out of warranty; they recommend I get it repaired locally. If I can't fix it myself, I'd like to have a fair idea of where the problem lies if I do have to take it to a professional. I'm reluctant to just go to Maplin and buy a new power brick in case the monitor kills it.
(The problem coincided with my planning to buy a larger screen, so I don't need it fixed immediately, but it's a very nice screen and it would be nice to pass it on to my partner.)
Response by poster: Disconnecting the brick from the monitor, and turning it off and on again at the mains brings the light on the brick back. But reconnecting the brick to the monitor causes the light to go out again.
posted by ArmyOfKittens at 1:39 AM on June 11, 2009
posted by ArmyOfKittens at 1:39 AM on June 11, 2009
Best answer: Ok, sounds like there's a short circuit inside the monitor. When power bricks are overloaded like that, they are often designed to go into a sort of emergency shutdown. This prevents more serious consequences like fire. When you disconnect the brick from the mains, you reset its shutdown circuitry.
Your problem is inside the monitor itself. Inside, there is a second power supply. It takes power from the power brick and generates several different voltages for the LCD controller, the LCD panel, and the backlight. This internal power supply is likely the source of your trouble. Probably one of the large switching transistors has failed or something.
posted by ryanrs at 2:03 AM on June 11, 2009 [1 favorite]
Your problem is inside the monitor itself. Inside, there is a second power supply. It takes power from the power brick and generates several different voltages for the LCD controller, the LCD panel, and the backlight. This internal power supply is likely the source of your trouble. Probably one of the large switching transistors has failed or something.
posted by ryanrs at 2:03 AM on June 11, 2009 [1 favorite]
Response by poster: That's great -- well, not great, but I know what it's likely to be now. Thanks :)
posted by ArmyOfKittens at 2:47 AM on June 11, 2009
posted by ArmyOfKittens at 2:47 AM on June 11, 2009
This thread is closed to new comments.
In any case, since swapping power bricks didn't fix the problem, something's wrong with the display itself. Probably the internal power supply that feeds the backlight or something.
posted by ryanrs at 1:33 AM on June 11, 2009