Wiewsonic VE710b black screen Flashing

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello,

I test L2 and L3. All are 3 ohms.

I test D4 and D12. It's ok for the 4.

D108 is à high voltage power rectifier. It's impossible to verify without unsolder.

That you think, it is necessary to verify ?

It could not be a bad transformer or CCFL ?

Good evening

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

Good photos, but difficult to tell.On the board that has the transistors missing D108 looks like that has been getting hot compared to the one on the other board.Also I would compare on each board L2,L3,D4 and D12,make sure the each measure the same and the solder on the L2 and L3 is good.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Ok

It's good ?

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

That is excellent, same on the bottom will be very good.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Oh excuse me.

I don't understand that you want.

And this ?

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

Unfortunately, they need to be taken directly from above,and with a wider view.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

And the second board

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello Rtech,

I make some close up photos.

It's difficult to do not be fuzzy

First the board one. I have 4 screens wiesonic VE710b and I openned 2.

One to take parts and repair the other.

I do not know if it will be sufficient to make you an opinion ?

Thanak's for you answer.

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

Well, how about some good close up photos of the bottom of the board.And bieleve me,dry joints on transformers associated with these transistors to cause them to fail, and you cannot really measure the transformers, without the proper test equipment, except for comparing the secondary resistance if the inverter transformers.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello and thank you for your answer.

I have difficulty in believing that the problem results simply from a defect of dry joints.

Why? (I try to explain) :

The defaut is the same on two boards (who comes from two different screens) and at the same place.

I try to mesure connections directely on the transformer (the pins which are on transformers) with differents liaisons on the board. It's ok.

I already burned out two transistors by making a first try. I would like to be on before redoing a try.

I have somme questions :

Can I make a try without connecting the bad part ?

How to measure transformers ?

How to measure tubes if that it's possible?

Thank's for you answer.

Have a nice day.

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

These usually fail on BenQ type Boards, due to Dry joints on the inverter tranformer associated with the pair that keep failing..suggest you resolder the transformer before replacing them again.

[rogebe]

Hello,

I am a french guy thus not very comfortable with the language.

I have four screens wiewsonic VE710b with the same trouble.

Black screen and flashing. Flashes are regular and constant when I start

I have open. No bad caps.

But two transitors are bads (short circuit) : C5706 (see the attachement).

I replace the both and the cap associate in unsoldering on another screen

The screen is ok for 30 seconds. I see the logo "no cable" but after black screen and flashing. The same trouble.

The two transitors are again bads.

If you have an idea to solution my trouble, do not hesitate.

Good weekend.

RGB