Dell E172FPb LCD Monitor Fix

Intro: Dell E172FPb LCD Monitor Fix

Problem: The monitor turns on for about 2 to 3 sec, is very dim and than goes blank but yet the power button is still green on the monitor.

Solution: Examine, diagnose and fix a Dell monitor with only a few tools and a repair kit bought of off ebay that consist of four (4) transistors and a fuse. Oh and all the hardware will run 5 bucks with shipping, instead 100$ for a new monitor.  

Tools: 
- Philips screw driver
- Flathead screw driver
- Multimeter
- Soldering tools

Hardware:
- Transistors x4
- Fuse 

STEP 1: Dismantle Monitor

Dismantling the actual monitor takes no longer than 10 min with very few components to worry about. 

Steps: 
1. Unscrew the four (4) screws that attach the base from the monitor and remove the base stand.
2. Along the bottom of the monitor case use a flat screw driver (preferably a panel popper so not to damage the case) and pry apart the housing. Continue all along the monitors sides. 
3. Once the back monitor panel is removed detach the power button cable. 
4. Remove the front panel by prying the four (4) clips along the sides of the panel. 
5. Slide the protective metal housing off the case.
6. Unplug the high voltage monitor plugs.
7. Unscrew the four (4) screws from the sides of the housing (two (2) on each side)
8. Slowly lift the housing and unplug the monitor cable.
9. On the outside of the housing, remove the two screws near the VGA input and remove the metal plate there. 
10. Pop out the plastic support above the power cable input. 
11. unscrew the seven (6) screws from the circuit board and one (1) screw for the ground cable.
12. Apply pressure from underneath the circuit board and squeeze the clips to remove the two (2) clips on the circuit board. 
13. Remove circuit board. 

STEP 2: Locate and Test Transistor and Fuse

Here we need to locate and test the four (4) c5707 Transistors. Unfortunately due to how the transistors work, we will need to unsolder them and test them outside the circuit via multimeter. 

Steps:
1. Locate c5707 transistors
2. Unsolder the transistors and tests them using the multimeter
3. replace the necessary transistor. I bought an actual repair kit off of Ebay for like 5$ or something like that. 
4. Locate and test fuse (replace if need be)

STEP 3: Replace Hardware

Pretty much follow step 1 to reassemble your Monitor.  Then hook up the monitor and pray that this worked. I'm now wizz on this stuff so if it didn't work I'm all out of ideas. Good Luck!

Comments

[pro2xy]

How do you check those transformers? and what should the pico fuse read when testing?

[vernon.bosshard]

Check voltage at the large power cap, first with power disconnected, short the leads of the cap to drain it, use your meter test lead and just cross both leads touching them. Then power up, if you have DC voltage at that cap your transformer and PS are probably ok. Not sure what the voltage is supposed to be. To directly check the Xformer you would need to power up and check the voltages in the secondary, but again not knowing what they are, its a guess.

[ketorolac]

may I ask, where is the fuse I should replace? Thanks

[vernon.bosshard]

Fuse on this one is near the power plug, its a white cylindrical tube with silver ends, you would need to unsolder one end, Check with ohm meter, should be near zero ohms.

[vernon.bosshard]

Do you know the gain on those transistors? Also I found 2 power caps with bulging tops, I went ahead and put new ones in, I had some on hand. Those electrolytic caps often fail with age. Then we pulled all those transistors, my meter said they were PNP????? Weird!! So I used the diode check on the meter, indeed found one that was farked. The others checked ok but I'm going to replace all 4. Will reply back after they are in, BTW we did this on a nice LG monitor, we found a link about that one and did the repair, works great. I have a degree in electronics but not much experience, I need things like this for practice. If you have a good DVOM and LCR meter, and a soldering iron you can do pretty well. If anyone has a question I might can help. vboss5764 at yahoo

[eneagud]

The same symptoms appear if one of the 4 neons embedded in the LCD top and bottom frame are dead. The circuit shuts down after a few seconds. I found that this is the most encountered fault in monitors older than 3 years. The process of replacing , soldering neon lamp terminals and put all back together is very hard but not impossible. One should try to disconnect the neons one by one and connect an external good one to see if the symptoms disappear, and the replace the faulty one.

[sahat]

Nice one, hope you also make sure re-solder all the small transformer leads otherwise the transistor might fail again.

Regards

[Polndsprin]

Thank you, Thanks for the heads up. Looks like I'm taking it apart again tomorrow to do that.