PCB Blog

Dell E173fpb Lcd Monitor Overheating & Shutting Off.?

Just looking at what is likely to be going wrong.
These monitors seem to have a common fault - blowing the 4 power transistors that drive the backlights.
I’ve replaced those, and the PCB fuse, but the problem persists.
It will be fine for hours - then the screen goes black. Green power button light stays on.
Turning off, then on will restore operation for the same ammount of time that it is turned off for, !0 seconds off - then on will allow it to stay on for around 10 seconds - so seems to be heat related.
All Connections around the transformers have been checked and ok - they all are. All Elec Capacitors look ok.
Two areas look hot. These are around the large power transistors (TO220 cases) on heatsinks. The board is a little brown under one of them.
As these are a bit expencive, I thought I would ask here before swapping them.
Could they be handling more current than they should - or being driven too hard ?
Any way to safely check ?
Any Ideas ?

4 Responses to “Dell E173fpb Lcd Monitor Overheating & Shutting Off.?”

1. ' slimRazor ' Says:
   November 10th, 2009 at 1:14 pm

   The protection circuit on Dell Lcd’s is generally a way of protecting the actual fluorescent tube from getting overdriven (too much current going through them). So when this protection circuit kicks off, it generally means there is either a short in the tube or a short in one of the components near / on the inverter. unless the LCD is quite old, its usually a short somewhere in the inverter circuits.

2. Joshua Says:
   November 10th, 2009 at 3:42 pm

   It could be a faulty wire somewhere. if a wire is loose or damaged it could still show light for a while and at a certain heat it acts as if - touches + and turns off stuff for it, such as a light. feel for broken wires/cables, don’t be afraid to bend a little just not too much, if it bends very easily somewhere then its a faulty wire. best of luck for your issue

3. nexvecte Says:
   November 10th, 2009 at 10:20 pm

   check your power levels on your entire mother board.check it against the spects.before you began to swap things .tou will save time and money

4. belladon Says:
   November 11th, 2009 at 2:22 am

   few….when it rains it pours!you might as well be asking me to fix the space shuttle….but here we go.do you have a warranty on this dell.an if you don’t, you seem to have a great knowledge of these things,you should be able to handle it.I do know that when I worked at an electronic plant,anything heating up on the bottom was bad an had to be replaced to pass inspection…that’s about all I know….but I send blessings of intervention to help you achieve your woes…Blessed be…!

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