Dell E172fpb

[Monitor Doctor]

Re: Dell E172fpb

So posting a source for a repair part that actually provides all the neccessary details for a successful repair to those stabbing around in the dark is spam? When i was enlightned with this info. i thought it a blessing.

[davmax]

Re: Dell E172fpb

A useful input. I cannot speak for all Benq LCD monitors but there is no doubt in my mind that the FP737s has several design problems that can allow the inverter transistors to be stressed to the point of failure, there is no adequate protection for overcurrent and overcurrent can occur on the rare occasions when a computer post removes video and then rapidly reapplies before the soft start circuit can reset. I have witnessed this problem in action and protected several monitors.
I am not sure if you have read my thread on this monitor.

[Sam]

Re: Dell E172fpb

This may help you guy's cutting up your case. Mount the mje3055 on the back side, just form the leads and solder in and it lay flat on the board has plenty
of clearance.

[charlesrg]

Re: Dell E172fpb

What is the solution for the Transistor to not burn again that the ebay people are selling ?

[Krankshaft]

Re: Dell E172fpb

They claim that resoldering the HV transformer leads and the joints around it prevent a recurring failure.

Read Davmaxs' post above for the real explanation.

[charlesrg]

Re: Dell E172fpb

I just got some TIP3055 (MJE3055T) over radioshack and the monitor is working with no problems, I don't know yet on the long term but right now it's okay.
Yes I did had to cut the metal to accommodate the huge tranny.
Wish you guys good luck and merry Christmas.

[charlesrg]

Re: Dell E172fpb

It's still working good. No problems at all. No smoke either.

[davmax]

Re: Dell E172fpb

I just got some TIP3055 (MJE3055T) over radioshack and the monitor is working with no problems, I don't know yet on the long term but right now it's okay.
Yes I did had to cut the metal to accommodate the huge tranny.
Wish you guys good luck and merry Christmas.

Interesting that you are doing so well with TIP3055. Not an ideal replacement, large and slow switcher. I guess you replaced a pair. Do they get hot?

Have a great Christmas.

[jay1000000]

Re: Dell E172fpb

Hi there, i've just come across an e172fpb. When i plug it in the backlights light up, the power button is solid green but thats it. No images, no floating logo or flashing power buttons. Im assumeing its the logic board, but pressing the power button will turn the monitor on and off so there appears to be life in the logic?. Any ideas.

[Krankshaft]

Re: Dell E172fpb

I had a Samsung that had a similar problem.

I ended up junking it since the logic board was $80.00 and the monitor only had an analog VGA input anyways.

If the power led lights up then the logic board is getting power and all the backlights come on then the problem most likely lies in the video logic.

As a last resort open the montior up and check for any bulging caps since that could cause all kinds of odd problems. If the caps are ok.

You will need a new logic board or junk the monitor for parts.

[HOODLAM]

Re: Dell E172fpb

I own a HP L1955 LCD which also has a problem with the Inverter/Power board. After Opening the back panel, I discovered it has a BenQ Inverter and Controller Boards. Many of the components are the same as what is mentioned in this forum. Thanks for all the useful info guys!

[Krankshaft]

Re: Dell E172fpb

I own a HP L1955 LCD which also has a problem with the Inverter/Power board. After Opening the back panel, I discovered it has a BenQ Inverter and Controller Boards. Many of the components are the same as what is mentioned in this forum. Thanks for all the useful info guys!

Cool I repaired the exact same monitor and have been using it as my primary monitor ever since. Check out my posts and pics in the Benq thread about this monitor.

https://www.badcaps.net/forum/showth...4&page=3&pp=20

After replacing the inverter driver transistors the monitor worked however when I hit the power off switch only one set of backlights would shut down and the picture slowly faded off of the screen due to the always on backlight.

It turned out that one of the inverter SMT 8 Pin switching FETs (that shut down the backlights during power off there is one for each set of 2 backlights) was shorted as well check out my pics of their location if the monitors backlight won't turn off after the repair.

The SMT FET in question had a nice bubble on the package which is never good a diode check from source to drain revealed a dead short. I even provided a link to the parts.

Only one was shorted but I replaced both just to be safe.

I was impressed with this monitor and I couldn't beat the free price .

[HOODLAM]

Re: Dell E172fpb

Thanks For The Info. I Opened You Attachment And Notice You Board Is Slightly Different To My Board But The Basic Pricipal And Layout Is The Same. I Find The Picture Quality And Overall Screen On The L1955 Is Better Than The Samsung 203b I Bought. I Have Attached A Pic Of My Board For You To See. I Am Of To Our Local Supply Store To See What Parts They Got!!!

[davmax]

Re: Dell E172fpb

From your picture this board has been repaired before. The inverter to the right has mismatched transistors, not a good idea at all (replace in pairs). Best to get 2SC5707 parts from eBay. Also the original MOSFET on the same inverter has also been replaced was originally like the one at centre of board (for the other inverter). This MOSFET change should not matter if well chosen. Have you measured and found any short circuited transistors? This is likely in the right inverter.

[Krankshaft]

Re: Dell E172fpb

It seems that they eliminated one of the heatsinks that my monitor had with the two rectifiers on it.

On the original board they probably wired lower value parts together to get a higher value on your board they probably used higher value parts thus eliminating the extra rectifiers and the extra heatsink.

I guess the bean counters found a way to save a few cents.

Davmax you beat me to it I was thinking that transistor isn't right .

Measure the 4 output transistors they are right above and below those gray capacitors. On my board they convienently labeled collector, base, and emitter for me.

Set your meter to Diode Check and measure from base to collector if you get nothing one way reverse the probes. Do the same from base to emitter you will probably measure a short on one of them (0.00).

Due to the way they are wired it may seem that two are blown when testing in circuit so once you find the set that shows a short remove them both and test them out of circuit.

To be safe its best to replace both in the set its even better to replace all four.

Also as Davmax said replace any of the substitutes with genuine Sanyo C5707s.

They can be purchased off E-bay cheaply.

http://cgi.ebay.com/2SC5707-C5707-Tr...QQcmdZViewItem

One guy who posted in the Benq thread installed counterfeit components on his board they got really hot and didn't work.

Installing a substitute without careful consideration on these monitors can cause them to not work or fail prematurely.

[Krankshaft]

Re: Dell E172fpb

Oh yeah and also don't forget to measure from source to drain with the diode check on your SMT fets on the other side of the board.

If you get a voltage drop in one direction they are fine if you read a short you will need to replace those as well.

On my monitor I had to make a second parts run online because I didn't check them.

[davmax]

Re: Dell E172fpb

It seems that they eliminated one of the heatsinks that my monitor had with the two rectifiers on it.

On the original board they probably wired lower value parts together to get a higher value on your board they probably used higher value parts thus eliminating the extra rectifiers and the extra heatsink.

I guess the bean counters found a way to save a few cents.

Davmax you beat me to it I was thinking that transistor isn't right .

Measure the 4 output transistors they are right above and below those gray capacitors. On my board they convienently labeled collector, base, and emitter for me.

Set your meter to Diode Check and measure from base to collector if you get nothing one way reverse the probes. Do the same from base to emitter you will probably measure a short on one of them (0.00).

Due to the way they are wired it may seem that two are blown when testing in circuit so once you find the set that shows a short remove them both and test them out of circuit.

To be safe its best to replace both in the set its even better to replace all four.

Also as Davmax said replace any of the substitutes with genuine Sanyo C5707s.

They can be purchased off E-bay cheaply.

http://cgi.ebay.com/2SC5707-C5707-Tr...QQcmdZViewItem

One guy who posted in the Benq thread installed counterfeit components on his board they got really hot and didn't work.

Installing a substitute without careful consideration on these monitors can cause them to not work or fail prematurely.

I have had no problems from this source of 2SC5707

http://cgi.ebay.com.au/2SC5707-C5707...sid=p1638.m122

It is likely that the 3Amp fast fuse (PF701) needs replacing, do not use anything other than this or the transformers may flame.

[HOODLAM]

Re: Dell E172fpb

O Well , Cant Seem To Find Any Trannies Locally!! Ebay Doesn't Ship To South Africa. Third World Country With First World Technology!! Will Have To Try From Another Source On The Net. The Board Has Not Been Worked On At All. Bought The Screen New From An Authorized Hp Dealer (came In A Seal Box!) Maybe They Found A Problem And Tried To Rectify In The Facorty Or Poor Design Issues!!

[HOODLAM]

Re: Dell E172fpb

The one transistor(c3117) is different to the other 3(2sc5707). Very strange!!!!! I at least managed to get all the caps! I am going to replace all the trasistors and caps on the inverter side just to be on the safe side. found a site http://www.bluestar-online.com which sell and ship components @ reseanoble prices. If spend say $40 on repairs compaired to replacing the screen, it worth it. EG- components price converted to Rands - R300-00 . New Hp L1955- +-R3500-R4800!!

[davmax]

Re: Dell E172fpb

1.The caps are not usually any problem. They do not make transistors in these inverters fail. Are use replacing with the correct Low ESR capacitors? More problems if not.
2. Why do you need trannies? Rarely these are a problem.
3. The link I posted for 2SC5707 will ship to South Africa.
4. Very strange that you bought this monitor supposedly new. I find it very hard to believe that this is a monitor patched by someone using odd parts before sale.
5. Have you checked the (701)fuse to see if it is blown. An open circuit when tested with a multimeter set for Ohms or continuity testing.