Viewsonic Optiquest Q19wb

[MBAJACE]

Hi, I have a 1 year old 19in LCD screen that works perfectly fine for 2-10 seconds and the backlights shut down. No sign of bad caps. I did an intense visual inspection. Many people have had this problem and a solution has never been posted. When the lights shut down I can still see info on the screen. It has to do with the backlights power regulation. I tested the voltage across several cap points on the board and it jumps from high 14v to low 14v.
I'm going to swap the 1000uf 25v with a radio shack 1000uf 35v. I saw it solves the problem on fixya. Is this safe? What would happen if I used a 1000uf 50v. I decided the biggest cap 1000uf 25v is for the backlights which seem obvious to need the most power.
Any advice would be great.

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Hi, I have a 1 year old 19in LCD screen that works perfectly fine for 2-10 seconds and the backlights shut down. No sign of bad caps. I did an intense visual inspection. Many people have had this problem and a solution has never been posted. When the lights shut down I can still see info on the screen. It has to do with the backlights power regulation. I tested the voltage across several cap points on the board and it jumps from high 14v to low 14v.
I'm going to swap the 1000uf 25v with a radio shack 1000uf 35v. I saw it solves the problem on fixya. Is this safe? What would happen if I used a 1000uf 50v. I decided the biggest cap 1000uf 25v is for the backlights which seem obvious to need the most power.
Any advice would be great.

If you saw on Fixya that rubbing horse droppings on the monitor would fix the problems, would you try that? In the world of capacitors, Radio Shack capacitors are the equivalent of horse droppings.

There are many causes for the 'two seconds to black' problem. Bad capacitors are one of them, replacing the bad caps with good ones will fix that. Radio Shack does not carry any capacitors that are likely to help, and may be worse than those presently in the monitor.

There are other possible causes, including a bad transformer, bad ccfl, bad solder joints where the wires are soldered on the end of the ccfls, bad diodes, bad glue, and a few more.

If you want help, follow the link about attaching pictures in my signature. Take good quality pictures of both top and bottom of the power supply / inverter and attach them to you next post.

PlainBill

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

HAHA, I understand. It did not fix the problem. I found a ebay supplier that had a cap set for 12.00. The radio shack cap didn't do anything. I will get some photos. The boards look good though, hopefully someone can notice whats wrong. I can only detect 14v in the board. I will get the pictures you want ASAP.
Thanks PlainBill

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

[retiredcaps]

Re: Viewsonic Optiquest Q19wb

Pictures of the back?

You will get much better focus if you use macro mode and take the pictures close to a window for better light (especially if it is sunny out there).

[retiredcaps]

Re: Viewsonic Optiquest Q19wb

Also just to give you an idea of all the possible problems that PlainBill is talking about, see this video (about 8 minutes)

http://www.youtube.com/user/preherte.../1/HMUazhb0bhc

I'm not saying your problem is represented in the video. I'm just trying to give you an idea of how many things you might have to check. He talks about all the possible problems pretty quick, but they are equivalent to what PlainBill is saying.

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

OK, I will try to get better pics.

[retiredcaps]

Re: Viewsonic Optiquest Q19wb

Is this under warranty? 1 year old?

Hi, I have a 1 year old 19in LCD screen

[PlainBill]

Re: Viewsonic Optiquest Q19wb

Is this under warranty? 1 year old?

Not any more!

Just for reference, the attached pictures are what I hope to see when I ask for pictures. I don't need close-ups of capacitors; three different angles on a heat sink won't excite me. A straight-on shot clear enough I can follow the traces - almost as good as Miss June!!

Troubleshooting 'Two seconds to black' issues is a work in progress. Eventually I hope to be able to get the process down to the point where we can eliminate a number of possible causes quickly. That goal is a long way away.

PlainBill

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

I'm still working on getting better pics but I found interesting readings from what I believe to be the transformer. It has the copper spun around it. The inner ( I think secondaries) are not reading any volts. Later down the board it steps from 120 to 136v
On the outside of the transformer it looks perfectly normal. Could this be the problem?

The two components (boxes) leading to the LCD were outputing 11v all evenly. This may be stupid but I hardwired the fuse to eliminate that as the cause. In fact I know its stupid. If I blow the board oh well. I'll buy a new one but I'd prefer to find the problem.

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

g

[PlainBill]

Re: Viewsonic Optiquest Q19wb

I'm still working on getting better pics but I found interesting readings from what I believe to be the transformer. It has the copper spun around it. The inner ( I think secondaries) are not reading any volts. Later down the board it steps from 120 to 136v
On the outside of the transformer it looks perfectly normal. Could this be the problem?

The two components (boxes) leading to the LCD were outputing 11v all evenly. This may be stupid but I hardwired the fuse to eliminate that as the cause. In fact I know its stupid. If I blow the board oh well. I'll buy a new one but I'd prefer to find the problem.

1. Even a poor picture is worth a thousand words. Word descriptions don't cut it.

2. Shorting out the fuse is a REALLY bad idea. Don't do that.

3. I've identified some points on the back. Note the two transformers, outputs O1, O2, O3, and O4, the two drivers, and the inverter controller.

4. What is the part number of the inverter controller?

5. What is the part number of the inverter drivers?

6. What is the resistance from O1 to O2? What is the resistance from O2 to O4?

7. The pictures are quite good as far as size is concerned, but I really need something sharper.

PlainBill

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

The #'s on the board are
ILPI-025
REV: F
2007.02.13.

On the blue power switching device
SPW-055 RoHS
NCE N 0830
GH-130 E217615

The two black drivers? leading to the display wires are
SPW-068 Rohs
LSE J06CH

I'm going to have to do some research on testing the resistance ( I know my meter can do it ).

Also I found a shorted pink resistor. There is an identical resistor next to it that is not shorted. There are 3 different sizes of pink resistors, it is one of the largest.

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

Picture I found, exact same.

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

Transformers measure .631 and .635 for 501 and 502 I'm going to do the 8 point check you posted awhile back for an identical power supply from acer

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

Oddly it was working again and when I tried power cycling it to see if it was fixed it is now back in 2 seconds to black mode. Also it was moved from 1 machine to another. I think it has some kind of memory to it. Is there a way I can bypass the back lights. Hard wire them on? The info is still showing up on the screen if I shine a led at it. All of the bulbs are fine.

[PlainBill]

Re: Viewsonic Optiquest Q19wb

My mistake, I forgot to attach the picture that goes with the questions I asked above.

PlainBill

[lucky13]

Re: Viewsonic Optiquest Q19wb

My recollection on this model is that it frequently has bad CCFL (one or both of the top lamps failed). You might want to get anpther set of lamp to check the lamps.

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

BTW I found 2 resistors that were shorted. Make any sense?

[MBAJACE]

Re: Viewsonic Optiquest Q19wb

It just ran again for about 10 min before I reset the settings on graphic card. CFLs are off again. In 5 or so hrs it should work again. I'm getting normal readings on the board. Just to resistors that seem to be shorted.