How To Repair Dell E172Fbp Display
Here are the instructions, and photos, how I did fix my DELL display E172Fbp LCD with a "flashing power light". This repair also works for model E171Fbp and E173Fbp. It may solve the "black screen" problem. An $8.00 USD repair. (5/12/2007)
Appears DELL LCD display (and similar models) have a common problem with the inverter circuit. Transistors goes bad and needs to be replaced.
This display have a nice screen, high definition and a pure-white light, but after a few months of use, the display just goes black sometimes until, finally, it doesn't power on anymore. The green power light just flashes.
As I had the bad luck to own one, I decided to fix it by myself and save $$$. First, I did a research on Internet and I found this problem is a common failure on DELL displays. Some websites indicates the transistors on the inverter goes bad.
*** WARNING: *** All displays have hi-voltage and can be lethal. Kids, don't try this at home. Read the disclaimer at the main page.
I removed 4 screws on the back of the display. It allows me to remove the base of the display.
I had to use a flat screw and remove the [back] plastic cover. Some damage was left on the plastic.
I did remove some foil and pry the latch to remove the cover to access the hi-voltage connector.
I had to pry 4 plastics pieces (two on each side of the display) and disconnect the hi-voltage connector. Usually, pink and white cables are CCFT hi-voltage wires.
I had to remove four screws on each side of the display before removing the metal cover.
Now, the hi-voltage wires should be unplugged, the control panel cable (the right one) needs to be removed and the foil needs to be opened to be able to unplug the TFT connector.
This is a tricky part: You should not remove the metal cover after the TFT is unplugged. There is a latch or fastener that holds the wires, so the wires needs to be free before trying to remove the metal cover.
Finally the circuit board is exposed. There are some screws that needs to be removed.
Screws on the 15DB VGA connector needs to be removed also.
Finally, the circuit board is exposed. On the red circle are the 4 transistors (driver) for the inverter. Those transistors needs to be replaced. The little black part is a fuse, I had to replace it also as, somehow, it went bad because a short circuit during testing. - My bad -
Here are the four bad transistors. This little semiconductor parts can handle up to 80V and 8 Amps. I do believe there is a defect on the design, I can't believe how those parts goes bad easily.
Yeap, those transistors have a short circuit. I had to replace all of them. I was looking forward to buy the original ones but the 2C5707 is really expensive. I found it on ebay but the seller wants to be a millionarie selling it.
The purchase price for EACH ONE is "only 0.99 USD", but the shipping and handling is $5.99 USD, plus $1.99 USD additional item, so... 0.99 x 4 = 3.96 + ( 1.99 x 3 ) = (3.96 + 5.97) + 5.99 = something like $16.00 USD.
I decided not to throw away my money.
I did a research, I found the NPN 2C5707 Handles about 80V and 8 Amps. The TIP3055 handles about 70V and 10 Amps and is an NPN, so I decided to purchase four 2N3055 TO220. So, let's see what happen.
Here is the TIP3055 compared with the C5707. Basically, those transistors are "compatible" and works fine. The only problem is the size. Not a big deal, there is plenty of room on the display. (I hope so)
I did solder the TIP3055 transistors and cut the tips.
I also had to remove the capacitors labeled as ".15J100" to make some room for the TO220 transistors.
Here are the transistors installed. I had to put the parts on that position because the metal cover have an angle and there is not enough room. I may be able to cut the metal to fit it better.
I did cut a business card to isolate the metal and avoid any contact between the transistors and the ground. Just in case.
After replacing the transistors, I had to assemble the display. To put it everything together, I just had to see the pictures.
Is alive! IT IS ALIVEEEEEEEE !
Just as I expected, it is working fine. The TIP3055 have a temperature limit of 300 oF and the display was working for a while and those parts only reached a temperature of 160 oF. I do believe it will work fine for a while. Not too bad for an inexpensive repair.
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