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Re: hp l1955 mosfet traces lift, need diagram
I seriously doubt that HP made that monitor, it came from either a contract house or a major manufacturer. I suspect HP doesn't even have service manuals for that product either.
Maybe, maybe, you can ferret out the true maker via the FCC number which it may or may not have; I've noticed that there are a flood of various consumer and industrial items sold without the once mandatory FCC approval and consequently, no number either.
FCC ID site
Even if you can find the maker's name, they may consider the content to be proprietary; during my active years of service work, I have been turned down dozens of times when trying to buy service literature.
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The SMPS is not triggering and driving the MOSFET and so this makes the +B voltage build up on the main capacitor to HOLD on without drain as there is no switch frequency to drive the MOSFET.
Please try and trace the feedback to the MOSFET, can be the SM transformer, the feedback circuit or also a short on the secondary side.
Inverter boards usually are replaced in full - even in a repair shop. There's little demand for board schematics. Next to this the CCFL tube could be broken instead, with the inverter board still working.
Inverter boards can be tested with an oscilloscope - just holding the leads near the board will show a 58 Khz sine wave.
Its either going to be the power board or the main board, My assumption would be the power board since those are the more lilely culprits to go out on those monitors.
Since neither one is readly available, check the fuses on the power board and then also see if there are puffy caps. If there is then replace them with ones that are the same UF rating and same or highter voltage.
The MOSFET that blew up will more likely to have the switch mode driver IC that went out with it also, you need to verify that the IC is good otherwise you will blow up the new MOSFET, you may be better off buying a new board from here: http://www.discount-merchant.com/ProductDetails.asp?ProductCode=1160140&Click=54985
By the time you order the new MOSFET and other parts it may end up more han $35, just a suggestion.
There usually screws hidden behind stick-on plastic covers on the front and or edges of the screen. Use a sharp point to lift off these covers to reveal the screws.
The bezel will also have plastic catches/clips that secures the bezel to the lid as well as double sided tape. Slip a thin blade between the glass screen and bezel and gently lift the bezel free. Start at a corner and gradually work along each side.
Be careful not the apply too much pressure on the glass (it is easily cracked) and be careful not to scratch the screen.
I was looking for the same part and discovered that it is an AP2761I
(capital i not one at the end). Documentation on it can be found at
I haven't yet found a supplier as, in this Dell E153FPf 15" LCD
monitor, neighbouring components R856, C856 and R861 are so burnt out
that I don't know what values to replace them with. If in return you could tell
me the values of components near your AP2761i-A, I would appreciate it.