Dell E152/153fpc

[daniel84]

Hello all,

I was hoping I could get some tips on replacing a bad cap or two on the inverter board for the afformentioned LCD. As mentioned in a couple other places on the forum this board has two HER-MEI caps rated at 1000 micro Farads, 16V and 105 C.

I looked up the caps on the Hermei website and it appears they have been upgraded or replaced. However, the caps I have appear to be of an older model HERMEI LE line. Since I am brand new to recapping I don't want to replace the current caps with ones that don't do the intended job. If anyone that is familiar with this particular recapping or LCD repair in general cared to give some tips on what kind of caps to use (exactly) it would be greatly appreciated. Thanks in advance!

[Krankshaft]

Re: Dell E152/153fpc

First off Hermei is a known crap cap brand and you should replace all of the caps on the secondary side of the supply. Since they in time will go too.

The proper type of caps to use on the inverter area are known as Low ESR or Low Impedance caps.

Panasonic FC series is a good one for inverters.

Also any low ESR cap from Panasonic, Nippon Chemi-con, Nichicon, Rubycon, or Samxon will do fine as well.

These are high quality capacitor manufacturers.

[daniel84]

Re: Dell E152/153fpc

Thanks for the reply krankshaft. I also noticed what appears to be discoloration of the board around the area of the affected cap. Is this normal or should I be concerned about damage elsewhere on the board?

[Krankshaft]

Re: Dell E152/153fpc

Discoloration on the board (assuming that area isn't near a high temp part like a heatsink, high voltage transformer, or switching transformer which in that case would be normal) having it around a cap signifies that the cap was overheating which is a sign that the cap is toast.

You didn't mention in your post whats wrong with the monitor?

Does it not power up or does it power up and shut down?

[daniel84]

Re: Dell E152/153fpc

We have about 10 (6 are already dead) of these monitors throughout the locations my company operates. Of the 6 that are "dead" I know 3 are exhibiting the following symptoms.

Black screen after about 1-3 seconds after being powered on. The power indicator remains green. Shinning a flashlight on the screen has revealed the picture is still there. After doing some research I found that a very common problem related to these symptoms was a bad cap at C922. An identical cap is located at C923. The inverter board part number is 715L1074-H and a good picture of it can be found here

http://www.lcdrepair.us/e152-e153fpc...ter-power.html

[daniel84]

Re: Dell E152/153fpc

I should probably specify that these are refered to as filter capacitors in a repair guide I found for my exact problem.

http://www.electronicrepairguide.com...or-repair.html

[Krankshaft]

Re: Dell E152/153fpc

That pretty much confirms my diagnosis.

Filter capacitors aren't a special type of capacitor filter describes the type of circuit that the cap is in.

A filter cap is located after a rectifier (which converts AC to DC) the caps job is to smooth out the ripple current the diode creates.

The cap passes the residual AC signal to ground while the DC continues on its way to power the circuit. It also acts as a energy storage tank if you will.

This is necessary since on switching power supplies energy only passes from the primary to the secondary of the power transformer when the switching transistor is off.

Conversely when the switching transistor is on no energy is flowing to the secondary however the filter cap still has energy from the PSUs last off cycle which allows power still to be supplied to the monitor during this "starvation period".

However since most switchers operate in the KHZ range (that is the switching transistor switches on an off thousands of times a second) this starvation period is very, very short.

[Krankshaft]

Re: Dell E152/153fpc

Oh yes and also check the 2 tiny through hole C5707 transistors on them.

If any of the monitors don't power on at all then they are your problem in that respect.

They are located (according to the picture at the site) right under the yellow power transformer and right above the high voltage transformer right on the left and right side of that blue capacitor.

A very common failure on Dells.

Anyhow to save yourself the annoyance on the intermittant units that are powering down you're better off replaceing all of the secondary caps.

Since the others you don't replace can go in short order. Caps are cheap and easy to replace.

[Krankshaft]

Re: Dell E152/153fpc

Ugh 10 minute post edit I hate you.

As for the board number you may be misreading it there is no real standard on where they are printed top, bottom, left, or right of the component.

You may be reading the board number for another part (I have done this many times). If the component is the same uf and voltage then thats your part.

[daniel84]

Re: Dell E152/153fpc

the transistors you refer to on this board are C5706... if that matters at all. I got the board number initially off the afformentioned website (lcdrepair.us) There is another number, F1074-H on the back of the board I had suspected to be the actual board number.

Since I am new to recapping I think I'll stick to replacing as few things as possible so as to eliminate as much "user error" as I can. I was planning on buying the caps from Topcat, what does he have that would be appropriate for my repair?

[Krankshaft]

Re: Dell E152/153fpc

Topcat only carries high quality brand name caps from my knowledge he sells Rubycons and Samxons just let him know that you need low ESR caps for your monitor and give the values and size and you'll be set.

[daniel84]

Re: Dell E152/153fpc

thanks again krankshaft... just waiting to hear back from topcat now.

[Machelle]

Re: Dell E152/153fpc

Did you get your capacitors ordered? Can you direct me toward which ones to order to replace mine on these exact same monitors?

[PCBONEZ]

Re: Dell E152/153fpc

Machelle
Where are you?