Viewsonic VE710b Power on black screen

[Guti904]

Re: Viewsonic VE710b Power on black screen

Perform a diode test for verification.

1) Set your multimeter to diode test.
2) Put your red probe on pin 1, black on pin 2. Report reading.
3) Put your red probe on pin 2, black on pin 1. Report reading.
4) Put your red probe on pin 3, black on pin 2. Report reading.
5) Put your red probe on pin 2, black on pin 3. Report reading.

2) 1 (Infinite resistance)
3) 240
4) 240
4) 0 Ohm

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

2) 1 (Infinite resistance)
3) 240
4) 240
4) 0 Ohm

Recheck the last reading. By the way, in diode test, all the units are volts, not ohms.

[Guti904]

Re: Viewsonic VE710b Power on black screen

There are mutiple VE710b versions.the monitor should also have a model number on,and they are all different as far as I can tell.As different manufacturers can use different components, different layouts and circuits to obtain the same inputs and outputs,anything goes.So unless you got the above tfmr details from exactly the same board as this unit has then that is probably the difference

The board model board is SLV03150450-00

[Guti904]

Re: Viewsonic VE710b Power on black screen

Recheck the last reading. By the way, in diode test, all the units are volts, not ohms.

Sorry, the last reading has 0 (there's continuity)

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

Sorry, the last reading has 0 (there's continuity)

That is a weird reading. It should be out of range. I say this diode is bad.

[jetadm123]

Re: Viewsonic VE710b Power on black screen

Another number that Viewsonic uses to identify the different revisions of the same model can usually be found on a sticker in the back of the monitor. It will read something like model: VSxxxxx. What is this number? It should help ID the power supply.

[Guti904]

Re: Viewsonic VE710b Power on black screen

That is a weird reading. It should be out of range. I say this diode is bad.

Sorry, i retest the last two readings:

3) 240
4) Open circuit....

So, that means the transistor is ok?

When i power on the board sounds noisy, i don´t know if this is normal or is because a faulty component.--

[selldoor]

Re: Viewsonic VE710b Power on black screen

Hi - you will have to be more exact as to where the sound is from roll up paper or thin card tube and try and pinpoint where its comes from.
When you have put the mosfet back in (with it all connected up) what voltages do you get on the connector to the main board. I see the main cap seems to be a Ltec, they are not the best - what make are the smaller caps - if they are ltec they will need upgrading.
Bad caps can contribute to noise as the voltages on the board are not stable.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Hi - you will have to be more exact as to where the sound is from roll up paper or thin card tube and try and pinpoint where its comes from.
When you have put the mosfet back in (with it all connected up) what voltages do you get on the connector to the main board. I see the main cap seems to be a Ltec, they are not the best - what make are the smaller caps - if they are ltec they will need upgrading.
Bad caps can contribute to noise as the voltages on the board are not stable.

The ouput voltages to the mainboards are 5V and 12V, the first thing I measured was those, when i turn on the monitor the screen blinks two times and then goes black, after 4 or 5 secs after, blinks again (i think the blacklights try to turn on but they can´t).

I will solder the transistor and make a video to show you what happens...

selldoor, what do u think about the diode's readings??

[selldoor]

Re: Viewsonic VE710b Power on black screen

If you have
2) 1 (Infinite resistance)
3) 240
4) 240
5) 1 (Infinite resistance)

In accordance with retiredcaps test instructions then it is OK.

Better post a pic of the mainboard front and back and the board
on the back of the panel [if this model has one] take care in handling this.

Have you been able to retest the inverter transformers yet.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Well that is odd - it looks very much like this

Right inverter transformer:

P1-P2: continuity
P1-P3toP6: continuity
P2-P3, etc: continuity
P1-S1: 618
P1-S2: 822
P2-S1: 618
P2-S2: 822

Left inverter transformer:

P1-P2: continuity
P1-P3toP6: continuity
P2-P3, etc: continuity
P1-S1: 614
P1-S2: 818
P2-S1: 614
P2-S2: 818

Both have the same readings.

Here's two pics from the mainboard

[retiredcaps]

Re: Viewsonic VE710b Power on black screen

If you have
2) 1 (Infinite resistance)
3) 240
4) 240
5) 1 (Infinite resistance)

In accordance with retiredcaps test instructions then it is OK.

The resistance and diode tests suggest it is okay, but there is still the question if it outputs the correct voltage.

[Rtech]

Re: Viewsonic VE710b Power on black screen

Perhaps we need to go back to basics here ! When you switch on the Monitor, I assume the Power Led comes on ?? then when you switch the Computer on and apply a signal, what happens to the Led ?? eg recognises the signal?, therefore changes colour ?, and stays that way?, or flashes all the time etc etc?. According to the resistance readings the Inverter tfmrs are OK.Outputs of 5v and 12v seem to be normal.I note this is the standard Royer type setup, so doubt,based on the symptoms,must be considered reference the timing caps and associated transistors, and of course the Backlights themselves.This really does highlight the importance of having some test Backlights,and unless these can be eliminated and/or confirmed as the problem,then,you are now going to have to test all the Royer components,and hope that they indicate where you go next.

[Guti904]

Re: Viewsonic VE710b Power on black screen

Perhaps we need to go back to basics here ! When you switch on the Monitor, I assume the Power Led comes on ?? then when you switch the Computer on and apply a signal, what happens to the Led ?? eg recognises the signal?, therefore changes colour ?, and stays that way?, or flashes all the time etc etc?. According to the resistance readings the Inverter tfmrs are OK.Outputs of 5v and 12v seem to be normal.I note this is the standard Royer type setup, so doubt,based on the symptoms,must be considered reference the timing caps and associated transistors, and of course the Backlights themselves.This really does highlight the importance of having some test Backlights,and unless these can be eliminated and/or confirmed as the problem,then,you are now going to have to test all the Royer components,and hope that they indicate where you go next.

When I power on the monitor, the power led comes on, the computer recognises the signal but no images appears, the screen remains black and blinks everytime, blinks two times with 3 or 4 seconds intervals. I will put the transistor in place and test it all again...

[Guti904]

Re: Viewsonic VE710b Power on black screen

I uploaded a video to show you the little sound makes the power board after power on. In exact time the sound comes out, the screen partially blinks.

here's the video: http://www.youtube.com/watch?v=CHpzS...ature=youtu.be

[selldoor]

Re: Viewsonic VE710b Power on black screen

Do you have any spare working lcd bulbs or another panel (broken or laptop screen might do) to substitute for the current bulbs.

Dont think you came back on this one - you really need to be able to try
another bulb on this monitor or these bulbs on another monitor.

If you cant you will have to try and get to the bulbs in the panel and see if the wiring or bulbs are burnt.

Can you identify where the sound comes from.

[Guti904]

Re: Viewsonic VE710b Power on black screen

I have in my work office a broken lcd monitor (only the lcd screen). I will remove the backlights and try it with this board...but the noise seems to come from the side of the main transformer, but cannot say the sound coming from it, but its from that sector...

[selldoor]

Re: Viewsonic VE710b Power on black screen

If the cables will reach you may not need to dismantle it fully.

[Guti904]

Re: Viewsonic VE710b Power on black screen

The mainboard sends to the power supply the on signal, but receives the correct voltage from the power supply?? I mean, if i disconnect the mainboard is posible to see in the screen the message (no signal?) without the intervention of the mainboard? (I'm asking supposing I can send the on signal to the power supply bypassing the correct pins or something like that...)

[Rtech]

Re: Viewsonic VE710b Power on black screen

CN6 goes to the Logic Board, is there any markings on the bottom of the Board to tell you what is supposed to be on each pin ?? with only six pins, it is likely that they are 2 x ground, maybe 2 x 5/12volts,1 x Dim/adjust, and 1 x BLON/ENA,Using the latter and ground you can apply approx 3v,maybe from a battery,Power the Power board ONLY,and have lamps plugged in, and if the Board is 100% the lamps will light.