Viewsonic VE710b Power on black screen

[Guti904]

Re: Viewsonic VE710b Power on black screen

I tested some components of the power board and this are the results:

Mark 1: L0606-817C (see pic)

pin 3 (black probe) pin 4 (red probe): reading: 0.83V - when backlights blinks the reading falls to 4V and back to 0.83V (always with the company of the "tick" sound and also the blink of the green power light)

pin 1 (black probe) pin 2 (red probe): reading: - 1.08V when backlights blinks the reading goes to 0V and back to 1.08V

Mark 2: Transistor (see pic)

leg1 (black probe) leg2 (red probe): reading: 12.8V, when backlights blinks the reading falls to 4.8V and back to 12.8V
leg2 (black probe) leg3 (red probe): reading: -12.8V, when backlights blinks the reading falls to -4.8V and back to -12.8V

CONNECTOR CN6 Power Supplu (to mainboard) see pic attached
black probe - red probe
1-2: -12.8V when blinks the backlights and power led, the reading fall to 4.9V and back instantly to -12.8V.
1-2: -12.8V when blinks the backlights and power led, the reading fall to 4.9V and back instantly to -12.8V.
1-3: -12.8v idem
1-4: 0V
1-5: -12.8V
1-6: -11.1V when blinks the backlights and power led, the reading fall to 8V and quickly to 1V then 9V and back 11.1V.

If I disconnect the mainboard from the power board, the tick sound dissapears but the readings in the CN6 of the power board (readings 1-1, 1-2,1-3,1-4 and 1-5 remains the same, except 1-6 reading is -10.4 V (instead 11.1V with the mainboard connected).

[Guti904]

Re: Viewsonic VE710b Power on black screen

Sorry, I forgot the pics!

[selldoor]

Re: Viewsonic VE710b Power on black screen

If you disconnect the connector to the panel does it make any difference
The one on the main board at the top in your picture.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Transformer 51031512-00 / LSE L0615F2 readings:

black probe - red probe
1 - 2 : 0V
1 - 3 : 341V and falls to 332V when backlight blinks
1 - 4 : 341V and falls to 332V when backlight blinks
1 - 5 : 0
2 - 3 : 338V and falls to 334V when backlight blinks
2 - 4 : 338V and falls to 334V when backlight blinks
2 - 5 : 0

(see pics)

[Rtech]

Re: Viewsonic VE710b Power on black screen

The pulsing Power light and voltages, indicate that you probasably have a short circuit in the Inverter section.You have next to each Inverter transformer a White Capacitor and on each end of them is a transistor.These, I point out AGAIN, are the Royer Components,AND are certainly the PRIME suspects.Put your meter on DIODE test, and measure each transistor the same way going from pin to pin and then reversing the leads,AND they should all read the same, in every way.These type of circuits are regularly used in Benq Boards,a lot being used in Older Dell models,and every time, I see a Power light going off and on, then at least one pair of these transistors will be short circuit somewhere.

[Guti904]

Re: Viewsonic VE710b Power on black screen

If you disconnect the connector to the panel does it make any difference
The one on the main board at the top in your picture.

I don't remember, i will try it and tell you what happens.

[Guti904]

Re: Viewsonic VE710b Power on black screen

The pulsing Power light and voltages, indicate that you probasably have a short circuit in the Inverter section.You have next to each Inverter transformer a White Capacitor and on each end of them is a transistor.These, I point out AGAIN, are the Royer Components,AND are certainly the PRIME suspects.Put your meter on DIODE test, and measure each transistor the same way going from pin to pin and then reversing the leads,AND they should all read the same, in every way.These type of circuits are regularly used in Benq Boards,a lot being used in Older Dell models,and every time, I see a Power light going off and on, then at least one pair of these transistors will be short circuit somewhere.

Thanks for the tip Rtech, I will test that diodes and will put the readings to see how whe proceed.

[budm]

Re: Viewsonic VE710b Power on black screen

That is my experience with failed BenQ monitors also, blinking power LED due shorted out (some will have E to C reading of 200 Ohms, not dead short 0 Ohm) 2SC5706/5707 because of bad tuning caps, bad solder joints.

[Guti904]

Re: Viewsonic VE710b Power on black screen

If you disconnect the connector to the panel does it make any difference
The one on the main board at the top in your picture.

The result is the same, with or without the panel connected.

[Guti904]

Re: Viewsonic VE710b Power on black screen

The pulsing Power light and voltages, indicate that you probasably have a short circuit in the Inverter section.You have next to each Inverter transformer a White Capacitor and on each end of them is a transistor.These, I point out AGAIN, are the Royer Components,AND are certainly the PRIME suspects.Put your meter on DIODE test, and measure each transistor the same way going from pin to pin and then reversing the leads,AND they should all read the same, in every way.These type of circuits are regularly used in Benq Boards,a lot being used in Older Dell models,and every time, I see a Power light going off and on, then at least one pair of these transistors will be short circuit somewhere.

I see, there's a white cap and two C5706 transistors. This are the readings of the 4 transistors:

Inverter pic1:

Front transistor
1-2: 0 Ohm
2-1: 0 Ohm
2-3: 116 Ohm
3-2: 151 Ohm
Leg1 and leg2 are shorted right??

Back transistor
1-2: 0 Ohm
2-1: 0 Ohm
2-3: 117 Ohm
3-2: 151 Ohm

Leg1 and leg2 are shorted right??

Inverter Pic 2

Front transistor
black probe - red probe
1-2: 494 Ohm
2-1: 487 Ohm
2-3: 1 (open circuit)
3-2: 506 Ohm


Back transistor
1-2: 494 Ohm
2-1: 487 Ohm
2-3: 1 (open circuit)
3-2: 506 Ohm

there's a way to void the faulty inverter to test the another?

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

I

Front transistor
1-2: 0 Ohm
2-1: 0 Ohm
Leg1 and leg2 are shorted right??

Back transistor
1-2: 0 Ohm
2-1: 0 Ohm

Leg1 and leg2 are shorted right??

Shorted, both are bad.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Is there a spare code to replace these diodes if I can't find the same?

What about void the faulty inverter? This can be done or I just have to wait after replace the transistors?

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

c5706s on ebay.

http://www.ebay.com/sch/i.html?_nkw=...rom=R40&_clu=2

Or you can use c5707s as most Benq boards use c5707s found commonly in lcds power/inverter supplies.

I have replaced my fair share of these burnt out c5707s as budm mentioned due to bad solder joints.

http://www.ebay.com/sch/i.html?_from...s&_stpos&gbr=1

[budm]

Re: Viewsonic VE710b Power on black screen

I use 2SC5707 in place of all 5706, 5707 has better rating.

[Guti904]

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.

[Guti904]

Re: Viewsonic VE710b Power on black screen

I have the rest of the monitor at home, so when I leave work I'll test it all together.

[Guti904]

Re: Viewsonic VE710b Power on black screen

I tested all, when I power on the monitor the screens appears with "Signal" the "No" word is missing and then goes to black. Also I noticed when backlights power on a white stripes on the left of the screen (about 2'' width), the rest of the screen is black with the cutt message "No signal". Any idea about this?

[Guti904]

Re: Viewsonic VE710b Power on black screen

Here's the pic. The message is "sgnal" instead "No signal" and also you can see the white stripes at the left.

[retiredcaps]

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).

[Guti904]

Re: Viewsonic VE710b Power on black screen

retiredcaps, I connect a source and now I can see what really happens... the screen looks perfect only the right side, the left side are partially with the white stripes, the rest black.