Viewsonic VE710b Power on black screen

[Guti904]

Re: Viewsonic VE710b Power on black screen

The vga cable have a ground connector to a screw of the mainboard (not connected right now). Could be this important?

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

The vga cable have a ground connector to a screw of the mainboard (not connected right now). Could be this important?

When we are doing remote troubleshooting, I have no idea what you are looking at. Thus, clear focused pictures are always a good idea.

[Guti904]

Re: Viewsonic VE710b Power on black screen

I'm taking about the connector from the mainboard that ends in a DB9 blue connector (VGA). The connector has a ground cable. More pics.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Check and reseat all your connectors whether you touched them or not. Always plug in a source (i.e. computer display your favourite wallpaper).

I put back all the connectors and everything looks worse now including the right side of the screen...

[killian6pk]

Re: Viewsonic VE710b Power on black screen

Hi guys, after search a lot, I found the C5707 transistor, I´ve replaced the two transistors 2 minutes ago, and I tested the power board with the mainboard and the panel board. I power on and the green power led turns on, then the backlights power on about one second and power off and after that power led change from green to ambar and remains in that status. My question is, without the screen connected, it's a normal behaviour or the backlights must be always on and the power led must remain green?
The reading of both C5707 between leg 1 and 2 is almost 8V when the backlights is on and falls to 0 when turns off.

If I remember correctly with this type of power board (BenQ design) there is also a small black fuse labeled: BEL 3A 125V http://www.digikey.com/product-detai...1017-ND/614969 I have actually seen a board with two of these fuses and a Transistor Labeled FU9024N http://www.digikey.com/product-detai...024N-ND/358230 I think there are two of these on that board also. I understand that all of these need to be replaced if you are replacing the C5705s. Hope this helps.

[Guti904]

Re: Viewsonic VE710b Power on black screen

If I remember correctly with this type of power board (BenQ design) there is also a small black fuse labeled: BEL 3A 125V http://www.digikey.com/product-detai...1017-ND/614969 I have actually seen a board with two of these fuses and a Transistor Labeled FU9024N http://www.digikey.com/product-detai...024N-ND/358230 I think there are two of these on that board also. I understand that all of these need to be replaced if you are replacing the C5705s. Hope this helps.

I think inverter is working ok with the replacing of the two c5707 (with the source connected now the image appears). The half screen image may be caused by a faulty t-con (mainboard) or a faulty screen (COF). I'm right?

[etecnics]

Re: Viewsonic VE710b Power on black screen

it happend on back lamp driver circuit issu replace the ccfl driver transformer ocilator trancistor i think its a c5707 x 4 and .22uf 200v x2 replace this parts and try 100%

[etecnics]

Re: Viewsonic VE710b Power on black screen

replace ur lcd display,100%

[Guti904]

Re: Viewsonic VE710b Power on black screen

replace ur lcd display,100%

I replaced 2 of the 4 c5706 transistors. Now backlights are working but i've half screen. So, I must to try something new, or the lcd must be damaged, maybe when the power board failed it damage the lcd cof (chip-on-film)? I must stop trying to fix this, and the solution is to replace the entire lcd screen?

[killian6pk]

Re: Viewsonic VE710b Power on black screen

I replaced 2 of the 4 c5706 transistors. Now backlights are working but i've half screen. So, I must to try something new, or the lcd must be damaged, maybe when the power board failed it damage the lcd cof (chip-on-film)? I must stop trying to fix this, and the solution is to replace the entire lcd screen?

Why didn't you replace all 4 of the C5707s? Usually when one or more go bad they all go bad or will go bad just after you replace one or two and then power back up again. You need to replace the two that you did not replace the first time.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Ok, but i'm still wonder if half screen behavior can be due to inverter problem...

[Guti904]

Re: Viewsonic VE710b Power on black screen

The two resistances near the c5707s are shorted also...so I think I must to change everything to leave the power board ok, but I'm concerned about the half screen image...

[killian6pk]

Re: Viewsonic VE710b Power on black screen

The two resistances near the c5707s are shorted also...so I think I must to change everything to leave the power board ok, but I'm concerned about the half screen image...

Get the components replaced, resistors, remaining 2 C5707s and then if you are still having that problem it will be easier tracing it down knowing those problems have been fixed. Also did you look to see if your board has the FU9024N Transistors. I have repaired 2 Dells, A Viewsonic like yours and I believe it was a Gateway that all had the same parts. When I was repairing the Dells the thinking at that time was to replace all of those components. I don't know if that has changed, but I will bet the same advice is still good. Oh and one other I repaired with this board was a BenQ. Still replaced all those transistors.

[killian6pk]

Re: Viewsonic VE710b Power on black screen

One other thing when you are changing the C5707s are you paying attention to how the old ones came out. I am not sure it matters, but the orientation might be important. I would make a note on each one that you remove whether it faced in or out with respect to the capacitor.

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

I am not sure it matters, but the orientation might be important.

It matters!!

[Guti904]

Re: Viewsonic VE710b Power on black screen

I read another post in the forum and say it can be a problem with the cable going to the t-con or that it's damaged. If backlights are working ok right now, I must not leave out the PSU and look elsewhere?

[Guti904]

Re: Viewsonic VE710b Power on black screen

Any idea?

[Rtech]

Re: Viewsonic VE710b Power on black screen

The resisitors you mention are probably not short, resistors of this type do not go short, and no doubt, you are reading them in circuit, which is causing the anomaly.The fault now that you finally changed the transistors, is more than likely to be the LCD panel itself.