4 dell E172FPB

[370forlife]

So I got all four of these and they have a couple of different problems.

One dosen't even power on, or do anything when plugged in. One turns on the power light, dosen't blink, and two that blink the power button like they should, but when they do the screen lights up for a second, then turns off.

[Demix]

Re: 4 dell E172FPB

Well first of all check Q759, Q760, Q740 and Q739 to see if they are the problem, also the Pico fuse - PF751 (check that on the two boards which light up for a sec then go out as its a likely culprit) also make sure all the solder joints are good, re-solder them if you have to. Im a newbie at this but i recently came into possession of one of these and thats what i came up with after researching on these forums =]

[PlainBill]

Re: 4 dell E172FPB

Well first of all check Q759, Q760, Q740 and Q739 to see if they are the problem, also the Pico fuse - PF751 (check that on the two boards which light up for a sec then go out as its a likely culprit) also make sure all the solder joints are good, re-solder them if you have to. Im a newbie at this but i recently came into possession of one of these and thats what i came up with after researching on these forums =]

Correction: A pico fuse is nothing more than a fuse in a miniature package. The power for the entire backlight system goes through the pico fuse. If it were bad, the backlights wouldn't even flash.

Your suggestion to check Q759, Q760, Q740 and Q739 is correct, but incomplete. Q743 and Q751 should also be checked. And all transformers in the inverter section (T751, T752, T753, T754) should be resoldered.

A LOT of information is in this thread.

PlainBill

[370forlife]

Re: 4 dell E172FPB

Any particular way to go about checking them? I've never done a monitor before.

[PlainBill]

Re: 4 dell E172FPB

Any particular way to go about checking them? I've never done a monitor before.

Ohmmeter, VOM, or DVM. My personal preference is a DMM with diode test function. On the E172FPb I have two of the C5707 transistors are shorted (show less than .05V in circuit).

Here's the situation. The C5707s will overheat and short due to a bad solder junction on the transformer (each pair drives one transformer). Each pair of C5707s get their power through a FU9024N, and the FU9024Ns get power through the pico fuse. The cycle runs like this: The monitor is plugged in. The power supply comes up and the logic board does it's self test and turns on the inverter. With one pair of C5707's shorted it will overload the power supply and the supply will shut down. The power supply resets and powers up again, and the process repeats. Each cycle stresses the associated FU9042N. At some point it will short, particularly if the monitor was cycling for several hours. Before that happens, it may be damaged.

It's possible the FU9024N was not damaged, but it's pretty much impossible to determine that without a $500 transistor curve tracer. Do a search of E172FPb on eBay, you will find a guy who is selling a kit of 6 transistors and a picofuse for $4.99. So you might as well say 'WTF' and replace all three. I have a single monitor that is bad, I'm going to order a kit.

Or you can order the C5707's in quantity 20 for $8.99 and the FU9024N in quantity 10 for $7.99 delivered and be able to repair 5 monitors.

PlainBill

[EGuevarae]

Re: 4 dell E172FPB

Ohmmeter, VOM, or DVM. My personal preference is a DMM with diode test function. On the E172FPb I have two of the C5707 transistors are shorted (show less than .05V in circuit).

Here's the situation. The C5707s will overheat and short due to a bad solder junction on the transformer (each pair drives one transformer). Each pair of C5707s get their power through a FU9024N, and the FU9024Ns get power through the pico fuse. The cycle runs like this: The monitor is plugged in. The power supply comes up and the logic board does it's self test and turns on the inverter. With one pair of C5707's shorted it will overload the power supply and the supply will shut down. The power supply resets and powers up again, and the process repeats. Each cycle stresses the associated FU9042N. At some point it will short, particularly if the monitor was cycling for several hours. Before that happens, it may be damaged.

It's possible the FU9024N was not damaged, but it's pretty much impossible to determine that without a $500 transistor curve tracer. Do a search of E172FPb on eBay, you will find a guy who is selling a kit of 6 transistors and a picofuse for $4.99. So you might as well say 'WTF' and replace all three. I have a single monitor that is bad, I'm going to order a kit.

Or you can order the C5707's in quantity 20 for $8.99 and the FU9024N in quantity 10 for $7.99 delivered and be able to repair 5 monitors.

PlainBill

I just received 6 units of those. Resoldered the T's, and got 3 working out of the 6 received and two I already had with that PS/Inv board. I will order the remaining three kits from eBay. I gues the most important thing here is to resolder the T's and anything that looks suspicious or else it will happen again. Obviously, replace any bad cap or even "good" ones in the known bad list. That's what I did.

[Demix]

Re: 4 dell E172FPB

thanks to this i just fixed my one, as i was resoldering two of the 4 transformers i heard a small pop and the solder spat at me ( i had safety goggles on) but this happened because there was a small air bubble below the solder which may have been part of the problem =] all i need to do now is fix up one of the 4 transistors as when i was replacing it one of the small little metal rings that the solder sticks to came off and i lost it >_< so i have to find a way to bridge the gap between the transistors leg and the circuit it needs to get to hehe =p should be okay though ^^