viewsonic n2751w dark blue screen

[raymond]

I've acquired a 27" viewsonic n2751w LCD tv-monitor. I've opened it up and it's been laying on a table now for a few days. I'm quite baffled. The backlight comes on, the screen has a fairly dark blue-grey color with a thin lighter blue vertical stripe (1/10 in. wide) down the middle of the screen. That's it, no picture, menu or anything else will happen. The control buttons do nothing at all. It turns on and off fine, the led turns green when on/red when off. I've looked over the two exposed boards several times, both sides. They look good-no bulging or leaking caps. Any ideas would be appreciated.
Cheers.......Ray

[hijodalgo]

Re: viewsonic n2751w dark blue screen

Pictures of the set will be more helpfull Ray,thanks..

[cadiman]

Re: viewsonic n2751w dark blue screen

I would start with the Main board. Run this tv model number on Ebay and you may find all the boards except the main board and that is really a good clue to troubleshooting any tv with little knowledge.

This helps me. I try to do this before I buy a bad tv. It will give you some insight and prevent you from buying junk...most of the time.

[momaka]

Re: viewsonic n2751w dark blue screen

Any ideas would be appreciated.

Either video board or panel board problem. I'd say probably a shorted ceramic cap in the power supply section of the panel board. Post some pictures of the panel board, particularly of the area with the inductor.

[raymond]

Re: viewsonic n2751w dark blue screen

Thanks for the replies. I have a lot to learn yet beyond spotting and replacing bad capacitors.
I'm working on pics of both sides of the boards now. I've become quite familiar with lcd PC monitors, having repaired quite a few now (thanks mainly to this forum). This is the second lcd tv I've come upon though and they can be more of a challenge.
Momaka .....excuse my ignorance, but By 'panel board', are you referring to the main large board or the smaller board (inverter board...I think) which is below the metal housing and leads directly to the screen?

[momaka]

Re: viewsonic n2751w dark blue screen

Momaka .....excuse my ignorance, but By 'panel board', are you referring to the main large board or the smaller board (inverter board...I think) which is below the metal housing and leads directly to the screen?

Well I haven't fixed many TVs either (actually only 1), but in LCD monitors, the panel board is the one that is usually permanently connected to the LCD panel (hence the name) with very thin ribbon cables. It's also connected to the video/logic board. The inverter is connected to the CCFLs.
Everything should be similar in your TV, though, since LCD TVs are more or less just large LCD monitors .

[Scenic]

Re: viewsonic n2751w dark blue screen

Well I haven't fixed many TVs either (actually only 1), but in LCD monitors, the panel board is the one that is usually permanently connected to the LCD panel (hence the name) with very thin ribbon cables.

that's called the t-con board

[raymond]

Re: viewsonic n2751w dark blue screen

Thanks for the responses I've received so far, they keep my enthusiasm up. I've included jpegs of the power board and main- video board. I'm thinking the problem is in the main board but I can't be sure. The back light works well. The screen shows an illuminated grey blue color with a thin bright blue vertical line running down the middle of the screen. I'm wondering if the entire screen is being reduced to that thin bright blue line. Any thoughts? Cheers......Ray

[momaka]

Re: viewsonic n2751w dark blue screen

Illuminated white/gray screen with no picture is more likely to be a t-con board failure. The blue line is a bid odd, though. If possible, post some pictures of the t-con board.

Meanwhile, I suppose it also wouldn't hurt if you check the voltage regulators on the video/logic board.
With the TV plugged in and turned on, measure the voltage on all of the voltage regulators on the video/logic board. I see 10 of them, but there may be more. These very rarely fail, but it's still worth checking. Let me know if you need help locating them.
The way you measure the voltage on a voltage regulator is you put the (-) multimeter probe on ground (any metal part of the case of the TV) and the (+) probe on the tab of the voltage regulator.
It also looks like your video/logic board has some HERMEI caps - they're known to be crap - but let's assume they're fine for now and just check the items I mentioned above.

[raymond]

Re: viewsonic n2751w dark blue screen

The screen is more a dull grey/blue color. I tried taking couple of photos of it lit up but there wasn't enough light to pic up the bright blue center line or background. Also, the menu buttons have no effect on the TV.
I will check the voltage regulators as you suggested. The t-con board is located on top of the screen housing rather than on the back making it a bit harder to get at. There is one more small board beneath the video/logic board
( about 5x5" in size ) with two ribbon cables coming off of it and into the T-con board.
What voltages should I be looking for on the voltage regulators and should I be checking every tab on each? ......Cheers

[PlainBill]

Re: viewsonic n2751w dark blue screen

The screen is more a dull grey/blue color. I tried taking couple of photos of it lit up but there wasn't enough light to pic up the bright blue center line or background. Also, the menu buttons have no effect on the TV.
I will check the voltage regulators as you suggested. The t-con board is located on top of the screen housing rather than on the back making it a bit harder to get at. There is one more small board beneath the video/logic board
( about 5x5" in size ) with two ribbon cables coming off of it and into the T-con board.
What voltages should I be looking for on the voltage regulators and should I be checking every tab on each? ......Cheers

The best approach is to report the full part number of each regulator, and the voltage on each pin. Some regulators are fixed output and the output voltage is part of the number. for example, AS1117-33 is a 3.3V fixed output regulator. Others are variable output (i.e., AS1117). And to make life exciting, pinout will vary from family to family. Generally expect output voltages of 3.3, 2.5, and 1.8 volts, but don't assume the regulator is bad if the output is some other voltage.

PlainBill