Dell E172fpb

[drdavidge]

Re: Dell E172fpb

Damn, spoke too soon. It has been working for 3-4 days now, but now the green light just blinks. Here is what has happened so far: Monitor died and would only turn on for a second or two before going black. Green light would stay on. I replaced those 4 transistors, put it back together and it worked fine for a few days. Woke up this morning and turned it on and the green light is blinking with no picture on the screen. What is the next step I should take?

I took it all apart again and found that Q760 and Q759 were dead, again. These were new ones I just installed a few days ago. Any idea why they keep getting damaged?

[jumba]

Re: Dell E172fpb

If it is one pair always failing then it's likely a shorted turn. This causes the transitors drawing higher than normal current. If one measures the current consumption in both ccts; the faulty cct will be higher. Solution find a replacement tranny or rewind it.

[9Shenandoah]

My new board works but causes the White Backlight to be on ALWAYS when its "OFF"!!!

I ordered a new Power Board from Norris in Texas.
My new board works but causes the White Backlight to be on ALWAYS when its "OFF"!!! The monitor works fine, otherwise.

I mean when Power off is pushed to "OFF" the screen shows "CHALK WHITE"
I switched my Pink and Blue Transformer Connectors ( the four pair on the left side) but it makes no difference)

I really feel BUMMED. Is their a workaround? I checked every single connection, everything is fine. PLEASE HELP!

[drdavidge]

Re: Dell E172fpb

Anyone looking to get rid of their dead board? I could really use the parts since we cant seem to identify the model number of the faulty transformers. Please let me know - thanks!

[9Shenandoah]

Re: Dell E172fpb

Anyone looking to get rid of their dead board? I could really use the parts since we cant seem to identify the model number of the faulty transformers. Please let me know - thanks!

can have mine

[sysconnx]

Re: Dell E172fpb

I know this topic has been around for awhile now but I thought I'll add a bit to it. Over 6 months ago I came in contact with a dell with the same symptooms described (flassing on for afew seconds and then off). I followed the fix described on the forum, replacing a pair of trsnsistors with teh ones avaliable from jay car (MJE3055) and it has been happy ever since ( 6 months or so). The other day, I managed to get another one of these dud lcd's so thought I'll post alittle something on how to do the fix.... (the first one I didnt hack the case off but the 2nd one i thought it would be good for a try, def think if theres a 3rd time around then I would keep the case in tact/

http://syscon.wordpress.com/2007/07/...klight-repair/

Looking at other results, this might or might not be the soloution, however Its better to have a try then to have a lcd thrown in the bin. If it helps anyone new to this problem then all good.

Best of Luck to everyone.

[jumba]

Re: Dell E172fpb

Thanx kmkbeni for ure dead board. Can confirm it has the same fault as mine did. Replacing both transistor pairs Q159,Q160 & Q139,Q140 before working out transformer parameters

[casper]

Re: Dell E172fpb


Now that I got your attention LOL

Is there anyone who can tell me the power output of pins 1-10 of the BENQ DS-1107A from the Dell E172fpb? Or maybe how I can power the 48.L9201.A11 AD Board/Logic Board from an outside power source such as a PC power supply.



PLZ TY

[kc8adu]

Re: Dell E172fpb

just rebuilt a big pile of these.
1.
replace all 4 2sc5707
2
resolder the whole inverter section.
3.
replace all the 470@35 with panasonic fc
the 1000@16 and 1000@10 i replaced with 1200@10 nc nrsz.
these are on +5.
of 18 of these units i reworked all have been running fine 48hrs and the 5707's are warm but not too hot to touch.
maybe i am just lucky i didnt get any bad trannies.
they all ring the same so i figure i am ok to sell these.
edit.
i added a 470@35 in a spot in the inverter where the design originally had one but was left blank by the beancounters.
cant hurt to have it built as designed.

[davmax]

Re: Dell E172fpb

It does appear that something causes the 2SC5707 transistors to fail. Has anybody a clue why?

If you see my postings about the Benq monitor I found that the overload protection circuit was worthless and have implemented one that does work. So far this has been proof of principle protecting after about 100uS delay. Shortly I will target a 10uS delay that will more positively protect the transistors if a short fault current occurs.

kc8adu I seee you have been ringing testing trannies. What tester did you use?

[gonzo0815]

Re: Dell E172fpb

Seems that KC8 success supports my assumption, that the bad caps and the attributed higher noise & ripple could be the root cause of these problems.

Especially, if the protection circuits are bad designed and the safety margin left from the designer had been removed by the bean counters.

[Krankshaft]

Re: Dell E172fpb

kc8adu I seee you have been ringing testing trannies. What tester did you use?

I always wanted a ringing tester I see alot of people using the Dick Smith tester online unfortunately they don't make them anymore .

[wongdabko]

Re: Dell E172fpb

This has been an incredibly valuable exercise and the solutions are about to be embarked upon for my Dell e173fpb monitor. The monitor came with a Dell Dimension 8300. At about 3 years old the monitor started the blinking light routine. The monitor worked fine when plugged into a laptop as second monitor. So my guess was a problem in computer (proably video card/drivers). Followed the 'reload video drivers' solution which did not help.

On inspection of the computer I found 4 blown caps on the Nvidia video card. These were replaced. The system worked well for three days. Then back to blinking. Tested the monitor on laptop again - no problems. So back to the computer case. Opened the case and found two blown caps on the motherboard. Replaced these, monitor worked fine for 1 week. Monitor went to blinking mode again. So I connected to laptop. Bloody monitor would not stop blinking! Now it is the monitor that's gone bad.

I am now going to replace all four 2sc5707 transitors (on order).

I wonder whether the blown caps on the video card may have been a precursor/cause of the monitor problems.

I am also looking at replacing the large diodes D751, D761. They are marked SB360 diodes. Specification on the web are 3 Amp, reverse Voltage 60V. Is anyone aware of problems if I replace them with 1N5822 which is 3 Amp and 40V or do I need exact replacement specifications. I am a real noobie but willing to learn.

Wongdabko

[gonzo0815]

Re: Dell E172fpb

As there is probably no voltage >40v i think it should be fine. Not sure about thermal resistance, but AFAIK the 1N5822 has an lower forward voltage and thus lower power dissipation.

Regarding the root cause of the bad monitor, i am inclined to deny any possible impact from the bad caps at your vid card and the board.

I would rather blame the caps, the general poor design of this particular monitor.

[wongdabko]

Re: Dell E172fpb

Thanks for that Gonzo, will post back when my repairs are done.

Wongdabko

[mypc2007]

Re: Dell E172fpb

Hello

I have Dell E173Fpc which open CCFL transformer. Does anybody know where i can buy the transformer?

Thanks
Rick

[davmax]

Re: Dell E172fpb

I had the same problem so knocked one up. See details here: https://www.badcaps.net/forum/showth...38538#poststop

I always wanted a ringing tester I see alot of people using the Dick Smith tester online unfortunately they don't make them anymore .

[davmax]

Re: Dell E172fpb

Looking at the inverter PCB in this thread it looks very similar to the Benq board, I suspect it is a Benq build. The transformers are the same as are the inverter components. In Australia we can get these transformers from Benq service agent (in stock) see: https://www.badcaps.net/forum/showth...38532#poststop

See also the Benq Q7T3 thread for a failure mechanism discovery and various solutions and results.

[Monitor Doctor]

Re: Dell E172FPb E173FPb The real cure!

Hello all,

I have repaired tons of the DELL E172FPb and E173FPb and I have NEVER seen a bad cap or a bad inverter transformer and I have NEVER had a unit fail after a repair. Everyone is dogging these DELL/BENQ units but they are EASY to repair if you know what you are doing. Here are two sources for the repair parts and they both provide needed info. for a successful repair:

http://search.ebay.com/search/search...ak1234&=search

http://www.lcdrepairparts.com

[Harvey]

Re: Dell E172fpb

^^^ Nice advert.


Or spam, as most people call it.