Wiewsonic VE710b black screen Flashing

[Agent24]

Re: Wiewsonic VE710b black screen Flashing

I repaired an other one.

2 on 4 but I do not have transistors anymore to be cannibalized.

Did you have a look on eBay?

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello

I repaired an other one.

2 on 4 but I do not have transistors anymore to be cannibalized.

Still one thank you.

Nice day for you.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello,

I have to go back up the board and the screen works again.

Thanks to all those who gave me somme ideas to repair.

Finally I have to change two transistors (Q10 and Q11), C3, to check condensers yellow and to resolder transformers.

Well I have two similar screens to be repaired.

Coming up next.

Good day.

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Up

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello guys,

I had no answer to my last questions.

Needs it to make the other thing ?

Thank's for you answers.

Good day.

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

I resoldered the two inverter transformers.

I measured the two yellow caps: 0.211 (scale 2uF).

I changed C3.

Good day for you.

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello,

Before switch on the board I think resoldered both inverter transformers.

As I have two same boards (in fact, I have 4 same screens), I took transistors and yellow caps (0.22µf) which was good to replace on the other board.

But I am going to unsolder the yellow caps and to verify their value

However I do not see these transistors " 100179 " ?

The reflextion on the post 23 is right ?

C3 is very important for Royer Oscillator ?

What is the fonction of C108 ?

Thank you for you interest in my problem.

RGB

[budm]

Re: Wiewsonic VE710b black screen Flashing

Post 20 also requested to check the capacitance of those two 0.22uf cap, but I am not sue if he did or not.

[viziks]

Re: Wiewsonic VE710b black screen Flashing

Please also check 0.22uf condensers between the 2 C5707 transistors.Defective capacitor will cause transistors to overheat.
I hope you must have also checked and resoldered both inverter transformers near the transistors "100179 ".

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Ok Budm,

I made a photo

In red the condensers which are before D108. It is a s à high voltage power rectifier. He has to feed both Royer Oscillator (inverters).

Transistors on the right was OK. Those on the left not

Normally caps in the red circle must be good

Rest C3 and C108 has to change

I am clear ?
It is right ?

Thank's for you answer.

RGB

[budm]

Re: Wiewsonic VE710b black screen Flashing

That bad filter cap C3 for the inverter power supply can cause the Royer Oscillator (the two C5707/5706, the tuning cap (0.22uf yellow cap), the inverter transformer) to run at the wrong frequency which will cause the transistors to run hot and burn up.
If I were you I will replace the electrolytic caps as a set, not just C3. Bad cap can look normal.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello budm,

You are right, the condenser C3 seems bad (the eye of master !)

For the yellow cap, I put it a which was between two good transistors.

Something else ?

Nice day to you.

RGB

[budm]

Re: Wiewsonic VE710b black screen Flashing

OK, just to be sure, the brown stuff on C3 is not from the cap, take it out and look on the bottom side of that cap. Check the value of the yellow cap sitting between the two inverter transistors and make sure they show 0.22uF.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello everybody

I do not know really any more how to solve my problem.

Somebody would have an idea ?

Thank you for your answers.

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello,

Excuse me for this silence I had some problems of connection.

But I admit that I am lost. I do not know that I do.

I try to think about a method of test to solve my problem.

Thank's for all informations that you give me but if you have any suggestions you can give please let me know.

Nice week end.

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

Both sets of CCFLs must be fitted to test,otherwise it will switch off anyway.You should be able to test this one on the bigger screen.The CCFLs will NOT cause the transistors to burn out.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

Hello,

It's that possible to measure the CCFL to verify that it works ?

If I understood well. You ask me to try on an exit then on the other one.

I think that I can try on the exit that transistors burn out.

Finally I have a last question. Can i try the CCFL on a bigger screen. I have one with the power is OK. Like that I can test it.

Can I connect the power with one CCFL ? It is going to destroy the circuit ?

Thank's for your answers.

RGB

[Rtech]

Re: Wiewsonic VE710b black screen Flashing

The BRown stuff on the board is probably nothing.With the CCFL,then you can test your lamps.Just disconnect the Top Screen Lamp that is in now, and replace it with the test one,You do not have to open the screen ,just leave the test one hanging loose,leave the normal Bottom CCFL plugged in.If the fault is the same then try replacing the Bottom one with the test CCFL, leaving the normal Top CCFL plugged into its normal socket.

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

I have a ccfl which comes from a bad screen (a vE710b) !

RGB

[rogebe]

Re: Wiewsonic VE710b black screen Flashing

What do you think of that ?

RGB