LCD Repair

[Computer-Lab in Basement]

So my dad had a Dell E172FPB LCD monitor, and about 2 months ago it gave up the ghost.  It would turn on and display something for about 2 seconds, then it would black out.  So I had looked it up on google, and found that these monitors were prone to failure.  They had defective transistors that, after a few years, would burn out and cause the backlight not to turn on.  I found that the simple fix was to just take out the bad transistors and replace them.  So the moral of the story is, if you have a bad LCD monitor with those symptoms, chances are it can easily be repaired to good as new condition.  Anyone else have this same problem with any of their LCD's?

[keyb_gr]

Reading up on this, it seems that while replacing these transistors will make things work again in the short term, they may eventually fail again. The root cause seems to be bad solder joints together with a design problem.

BTW, aren't those the kind of Dells with these awful vertically arranged menus?

[Computer-Lab in Basement]

idk what the menus look like.  Even if the transistors aren't the cause of the problem, it only costs $4 for a repair kit, and the transistors can last about 3 years, so $4 every 3 years plus a little work isn't that bad.  Plus, it will give me something to do every 3 years.

[Computer-Lab in Basement]

I have to work to get my good computer equipment.  This being my first and only LCD monitor, I knew I wasn't going to be getting the best thing in the world.  Either way, I am still happy I was able to fix this one.

[InSanCen]

I have a samsung 4:3 19" LCD here that I got for nothing. Previous owner moved it about a lot, and consequently unplugged the VGA cable a lot. Re-soldered it, and hey presto. One monitor for browsing (19" Fujitsu-Siemens 16:10) and the aforementioned Samsung for code and other misc junk. Compiz on multi-monitor setups is just great... I just need to get that 7" touchscreen modded in on the S-Video connection now... mmmm....

[Computer-Lab in Basement]

I just got back home and I have plugged in my repaired LVD monitor and it is working beautifully.  I am not use to using an LCD monitor, it is so alien to me...

[Rajagra]

Normally if an LCD goes dark it's a failed inverter board and you just swap it out. But if you can pin it down to the exact component (or two) so much the better.
Be careful of high voltages when you poke around these things. They are safer than CRTs, but can still be nasty.

[Computer-Lab in Basement]

When I looked up how to fix it, the instructions said that the problem was 4 transistors on the inverter board that had gone bad.  It was a simple fix.  I didn't have any trouble with it, me and my dad unsoldered the old transistors and soldered in the new ones and now I have one decent LCD monitor.

[Hak Foo]

When I looked up how to fix it, the instructions said that the problem was 4 transistors on the inverter board that had gone bad.  It was a simple fix.  I didn't have any trouble with it, me and my dad unsoldered the old transistors and soldered in the new ones and now I have one decent LCD monitor.

I had a Viewsonic VX910 which I spent $350 on, replaced with a $65 secondhand 21" CRT.

After about 3 years, it went to 'power, no picture'.

A bunch of bulging capacitors on the PCB.  Replacing 'em did nothing.

I will stick to super-off-brand names now

[timw4mail]

That reminds me, on of these days I should fix the DVI port that went poof on my Sceptre X22 monitor...

[microsoft windows]

Doesn't it have a VGA port too? If it does, then that shouldn't be much a problem as it is.

[Computer-Lab in Basement]

Only one of my computers has a DVI port, and the monitor for it is VGA, so I just use the VGA port instead.  What is the major difference, besides the pin configuration?

[keyb_gr]

Only one of my computers has a DVI port, and the monitor for it is VGA, so I just use the VGA port instead.  What is the major difference, besides the pin configuration?

DVI can also carry an analog VGA signal (DVI-I), but the interesting thing is the digital transmission (TMDS). No syncing mess or varying black and white levels, always a stable picture. Analog outputs are better if you have really long cable runs, but for normal use DVI has much superior handling.
(Even though there are some monitors like my Samsung which take much longer for a mode switch than with analog input and even show occasional drop-outs at times (not sure whether it's my sample or the model in general). Whoever decided that the backlight was to be the first thing to be turned off upon signal loss deserves to be fired. Eizos are much more smartly designed in this regard, but it's a pity they couldn't do anything but full-screen interpolation for a long time.)

[timw4mail]

Only one of my computers has a DVI port, and the monitor for it is VGA, so I just use the VGA port instead.  What is the major difference, besides the pin configuration?

Except the picture is sharper with the DVI connection.

[keyb_gr]

Except the picture is sharper with the DVI connection.

Dang, I knew I'd forgotten something. Yeah, there are plenty of cards with lousy analog outs out there... beware of any low-profile ones which have the VGA out attached by a ribbon cable. A number of generic GF2MX cards was pretty blurry, too.

My work PC had a 1600x1200 Eizo L885 20" screen on a Matrox G550 (analog out, as DVI is limited to 1280x1024 on these cards) - no complaints about sharpness, but I could never get timing 100% perfect. It was good enough, but a pixel-level checkerboard pattern (think Win2k shutdown dialog and such) always showed a bit of flickering.

[bsvP585hUO2Y6]

keyb gr wrote on 5949 September 1993:

> Quote:
>
>     Originally Posted by timw4mail View Post
>     Except the picture is sharper with the DVI connection.
>
> Dang, I knew I'd forgotten something. Yeah, there are plenty of cards
> with lousy analog outs out there... beware of any low-profile ones
> which have the VGA out attached by a ribbon cable. A number of generic
> GF2MX cards was pretty blurry, too.

A lot of cards also sport overzealous low-pass filters behind the vga
socket for EMI reasons.  Shorting these increases the chances for a
perfect analog picture.  IIRC there was some article about it in the c't
magazine a decade ago.

> My work PC had a 1600x1200 Eizo L885 20" screen on a Matrox G550
> (analog out, as DVI is limited to 1280x1024 on these cards) - no
> complaints about sharpness

I can confirm: Eizo + Matrox = perfect image on LCD via analog.
Luckily, I'm no gamer and thus can live with my Matrox Millenium II with
4MB RAM just fine :-).  I used to have an AGP G400 but needed to
downgrade due to lack of a suitable slot when I upgraded the
Mainboard...

> but I could never get timing 100% perfect. It was good enough, but a
> pixel-level checkerboard pattern (think Win2k shutdown dialog and
> such) always showed a bit of flickering.

I can get perfect timing, but the temperature drift sometimes thwarts my
attempts.  +/-3°C and the phase is slightly off, needing readjustment.

[Rajagra]

My Dell 2405FPW screens do an amazing job with analog 1920x1200 signals. I switch between DVI and VGA to use my 2 PCs, and I really can't tell the difference. The colours probably suffer more than sharpness - converting from digital to analogue in the PC, and then back to digital within the TFT creates two unnecessary conversions that have to have some effect.

I can't use an analogue KVM though - the ghosting is horrible at these resolutions.