ACER AL2423W - no display

[Winstar]

Re: ACER AL2423W - no display

Well another 5 years would be enough for me... Then will be time to buy an OLED monitor

But I am afraid to buy the board(s) and not fix the problem... In addition I don't think backlight will last forever, but I must say I used it almoust always at minimum brightness

[Blacklite]

Re: ACER AL2423W - no display

I have the same monitor, and after 3.5 years of faithful service, it's finally given up. It started hissing/beeping (blowing cap sound), so I turned it off, then turned it on again and got no picture and the beeping was still going, so I turned it off again.

Now I've taken it apart, and it is pretty clear where the culprit lies:



It's the biggest capacitor on the PCB, marked "C1".

When I touched the back of the screen as I started to take it apart, I noticed it was very hot to touch. The plastic was very hot, and the screw holes for the stand almost burnt me. There are a few burn marks on some of the components around the bulging capacitor in the picture. Not sure which bits are relevant exactly, but I'm going to get my photographer colleague to take a quick picture of it tomorrow at work (my phone's camera is a potato).

There are also black marks (burn marks?) along where the heatsink above these components meets the PCB. I believe this all happened when the capacitor blew.

Should I just try replacing the bulging capacitor? I can't seem to find a schematic for this board, the service manual for this monitor doesn't have it as far as I can see.

I have a fair idea of how capacitors work and I know they can be very dangerous. I've done plenty of soldering before and basic electronic stuff, is this something I should be tampering with? Realistically, my only alternative is to throw the whole thing out and buy a new screen (replacing the power board is too costly considering the current value of the screen).

Thanks in advance!

[Blacklite]

Re: ACER AL2423W - no display

Can't seem to edit my post... Oh well, here's another picture of the board from a different angle:

[tron]

Re: ACER AL2423W - no display

replace the others too (all of them)

[Behemot]

Re: ACER AL2423W - no display

Yep. Use quality low-ESR caps for the bigger ones and low-ESR or GP purpose for the small ones - there have a look into datasheet to gain the idea what the replacement parameters should be.

As for the high-voltage input cap, I suggest lines like NCC KXJ and similar, they have very long life (10000+ hours).

I just by the way got the display again, the diode once again burned itself but now completely; probably the leg was too much oxidized and the solder did not attach it even it seemed that way. Since I didn't have 1kV+ standard diode, I have used 5A/1,7kV diode from old CRT TV/display in TO-220F package and used parts of it's legs as conductor also. It has slightly higher drop but is bigger thus should also transfer heat better. Hopefully it will last this time, it's soldered propely. If not, there would be interesting effects

[Blacklite]

Re: ACER AL2423W - no display

Thanks for your help so far. I'm pretty confident I can do all this, as long as I can find the right parts. Does anyone have a schematic for this board? I tried searching for one last night but no luck...

Also I'd like to know where all that heat came from too, so I can be sure that replacing these caps will prevent it from happening when I plug it in again. Anyone got any ideas?

[Behemot]

Re: ACER AL2423W - no display

Most likely it was so bad, having high ESR thus heating itself.

[desqa]

Re: ACER AL2423W - no display

Hello.
I'm trying to fix monitor with the same power supply as mentioned in post #5 - DELTA ADP-58AF. I replaced all the capacitors and main MOSFET (Toshiba 2SK2843) but found out that Zener diode right next to it is shorted... And here's my problem, I don't know the value of this diode (ZD4). I can't find any schematic for this power supply, and the only information I have is the marking of the diode that remained on the glue after desoldering... I think it's either "81" or "18". Is it possible that this is a 18V Zener or is it some other marking?

Any help would be greatly appreciated, thank You.

---
Below are photos before and after desoldering.

[juhae]

Re: ACER AL2423W - no display

Hi, my ACER 2423 backlight turns on only by unplugging inverter board cable from the PSU. Just short flash was visible during power on. After power on: Disconnecting/connecting pin 6 makes backlight to turnon. I cut the cable and soldered a switch to make short cut in on/off backlight control.
I have to replace caps from primary side of 19 V.

Here is link to shematics:http://www.manualslib.com/download/2...Acer-X241.html

[juhae]

Re: ACER AL2423W - no display

Hi, my ACER 2423 backlight turns on only by unplugging inverter board cable from the PSU. Just short flash was visible during power on. After power on: Disconnecting/connecting pin 6 makes backlight to turnon. I cut the cable and soldered a switch to make short cut in on/off backlight control.
I have to replace caps from primary side of 19 V.

Here is link to shematics:http://www.manualslib.com/download/2...Acer-X241.html

Ha! There is no diagram of power board AND Pin is 1 ( not 6). Sorry for mistakes!

[dondrusco]

Re: ACER AL2423W - no display

I received brand new power board for AL2023. Problem still persists - I have to continue with control board, it looks like backlight-on signal falls too low. Power led stays green.

I have another chance to swap parts between three monitors.
Gericom T2000 - faulty LVDS cable
Acer AL2023 - turns the backlight off after a while
Acer AL2423 - backlight problem.

AL2023 + logic board from AL2423 - backlight problem persists
AL2023 + panel from T2000 (the same model/revision) - backlight FIXED!
Some CCFT has a problem
AL2423W - recapped primary capacitors (C22,C24,C25,C30,C32) - backlight FIXED!
Couriously, the T2000 backlight works fine with no issue with panel from AL2023...

[QuickFix87]

Re: ACER AL2423W - no display

I have recently fixed such a monitor. It went black after several minutes in use. Replacing 7 capacitors CS 10/11/12/13/14/15/16 fixed this problem. At least 3 of them were clearly broken. Replaced all of them for the surefire result.
Also, the resistor R59 on the same power unit PCB seemed to be burnt. It was in black dust. I wiped this dust. Its body looked whole. I detached it. Its resistance was 826 KOhm. I thought it was too high for that place and concluded that it was broken. And read its color rings backwards. The resulting resistance that I calculated this way was either 1.3 or 13 KOhm 0.5%. I was unsure as the brown ring looked almost identical with the red.
Yet, after first replacing the original 826 KOhm resistor with a new one of 1.3 KOhm the screen was black even with good capacitors. After a while I figured that those 826 were close to the standard 820 KOhm, so it was fine. I put back the original resistor and the screen started ok.