Acer AL2423W Recapped, backlight works but no display

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

Hello, Per.
All the same I managed to recover the monitor. The last time when the monitor has again refused to work, I has thrown it in a far corner. Then, after a while has decided again it to look. Has checked up an oscillograph all power supplay - all normally. Has then looked Flash-rom - activity on information outputs is watched, i.e. the processor and flash work!

Began to look further, and in at last has found the reason - diode D18 in the voltage regulator on 1.8 volt.
On it too big voltage fell, and this defect was not to constants (that appeared disappeared). Has replaced, flash-rom didn't become flashing, at once has included - the monitor has worked.

Per Hansson, the same adjustments at me too aren't saved, but I any more don't pay attention to it.
Earlier I had a version firmware 1.3, and they be 1.0.

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

I gave this monitor to my parents years ago, it started developing a problem quite a while ago that I have not taken the time to try and really fix until now:
The monitor would turn on fine from cold but would after being on for some time display a "No Signal" message on the screen even though it was still working fine.
In the very first post I mention this:

(Actually I cheated and did not replace the 10uF CapXon because I had problems removing the grounding shield, also I did not replace the 450v bulk filter cap next to it)

So I thought this would be a good place to start, I replaced the 82uF 450v CapXon KM with a 450v 100uF Nichicon PT capacitor.
And the 10uF 50v CapXon KF I replaced with a United Chemicon KMG 10uF 50v capacitor.
As I was curious to find the actual culprit I did not do anything else with it. (The old caps measured good though).
And only after did I find this quote in another thread:

Which caps would you recommend instead of CapXons KF 10 uF/50V (120 ripple, 2 impedance)? I tried Chemi-Cons KMG, but it was not working (power supply went into safe mode almost directly). Samxon's GK 22 uF worked for ten hours, than I gave it to a guy for long run test and it went into safe mode after 10 minutes. What about GK 10 uF? According to Joe's web, they have 285 ripple, 0,03 ESR.

My monitor did not seem to be worse off with the KMG capacitor though.
But the original issue with the "No signal" did come up again after a few days.
(It was a very rare intermittent problem that I only witnessed myself once or twice)

So for the next thing I went back to the main PCB, there where some low capacitance Teapo SH capacitors that I had not replaced.
After disassembly I noticed that there where two different values: 47uF 10v which I did not really have a good substitute for with me.
And 22uF 25v which I decided to replace with 22uF 50v UCC KMG capacitors.
I tested each one on my ESR tester and measured capacitance with my DMM as I desoldered them and got more and more annoyed because they where all measuring good at around 1.0 to 1.5 in ESR!

But finally on the 10:th and last capacitor I found a bad one at 7.4 in ESR!
It sat right next to the input power pins that connect to the power PCB (old picture here with it in the top left on the green PCB).
Which looking at the markings on the PCB seems to be related to the "ON/OFF" circuit of the monitor, so quite logical after all
This was around a month ago now and the issue has not come back so it seems it was a good fix

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

This little monitor just keeps on giving!
After posting the message above that the monitor was working fine even using the same capacitor that Behemot said he had problems with mine developed the same fault!
So I fixed one "no signal" problem where that message would just be displayed while the monitor was still working, only to be replaced by a new one: monitor shut down completely after some time of use!

So I looked at the specs of the startup capacitor and just like Behemot said the one we both used as replacement was quite far off from the original.
So I searched Elfa and found this one which matches the original quite well when you take the ripple frequency in the datasheets into account Elfa partno: 167-04-347
It's a NIC Components NRSZ Series capacitor partno: NRSZ100M50V5X11
It's been working fine since putting that in some weeks ago. (Touch on wood).
Let's see if I broke it again by just saying that!

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

But the original issue with the "No signal" did come up again after a few days.
...
So for the next thing I went back to the main PCB, there where some low capacitance Teapo SH capacitors that I had not replaced.
After disassembly I noticed that there where two different values: 47uF 10v which I did not really have a good substitute for with me.
And 22uF 25v which I decided to replace with 22uF 50v UCC KMG capacitors.
I tested each one on my ESR tester and measured capacitance with my DMM as I desoldered them and got more and more annoyed because they where all measuring good at around 1.0 to 1.5 in ESR!

But finally on the 10:th and last capacitor I found a bad one at 7.4 in ESR!

The monitor once again did the "no signal" problem while still displaying a picture.
So this time I did the last remaining capacitors: the Teapo SH 47uF 10v where replaced with UCC KMG 47uF 25v capacitors.
And it's back to working again!
Now since it's been 7 years since I started this thread maybe I have to start all over again soon

This little monitor just keeps on giving!

...And giving

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

I have now located another reason for the "no signal" message being shown while the monitor still displays a picture.
It's a firmware issue! See below quote from Acer service bulletin for the Acer X241.
(The X241W monitor is basically the same without adjustable stand and speakers).

I posted a screenshot of how the service menu looked in the first firmware I found way back then.

I did some more searching, and found a user that has uploaded another firmware on a Russian forum since after the first one I found.
The version string shown in the service menu in this version is still v1.00 but it's obviously different because there is a panel selection menu for example.
The first firmware I found did not have that, and it also did not support the actual panel that was installed in my monitor:
A Samsung LTM240M2-L02, which explains the issues I had with color balance after I got it working back then.

To see the firmware version: turn off the monitor with the soft-off button.
Then press Auto and the soft-on button simultaneously.
If successful the power LED should now be amber instead of green.
Next press "menu" and it should say "Factory mode" if it does you press "menu" again and you are in the service menu.
Be careful in here: just take a picture of the service menu calibration values.
Then power off the monitor with the soft-off button.

Then you can dump the current firmware for safe keeping using an external programmer, the chip is U8 on the PCB.
Next flash it with the firmware attached to this post.
I have run mine for 6 months now with this firmware and it seems solid so far
Clarification: the firmware attached to this post is not the same as the Acer service bulletin below references.

DATE: 04/03/08 NUMBER: mn_029

SUBJECT:
REVISED - The message "No Signal" sporadically appears on the screen.

AFFECTS: X241 monitors ET.L990B.029

ISSUE:
This is an update to the document original published 9/19/07
While the X241W monitor is in use, it might show "No Signal" on screen abnormally.
Sometimes, the monitor may still continue to display video.
Other times the monitor may be go black. For some customers, the problem will correct itself in a minute. These problems often occur during the first 20 minutes the monitor is powered on.

SOLUTION:
Short term #1 – Unplug the monitor to reset the video controller.

Long term #1 - The main board firmware can be reflashed to a newer version of
firmware by an Acer authorized monitor repair depot. The latest firmwares are listed below.

for monitor with s/n version “00” and ”10” FW = WDTD-D1AP0 V1.03
for monitor with s/n version “12” FW = WDTD-D1SP0 V1.02
for monitor with s/n version “13” FW = WDTD-D2AP0 V1.03

ACTION REQUIRED:
Confirm the firmware has been updated prior to returning the monitor to the customer
or to stock.
When an Acer service repair technician updates the firmware, they should record that
the part IN-MONITOR was used.

SPECIAL TOOLS
6K.ISPVE.001 Tool Kit with a corresponding DB-15 and Serial data cable.
USB-A to USB-B cable for power.

PARTS REQUIRED
Replace main board if firmware update does not resolve the problem. See spares parts list for p/n.

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Got some news
I bought another mainboard on eBay about a year ago, because it had a newer firmware:
The firmware version is actually printed on the back of the PCB on a sticker, this new one was CKS: 7F70 VER: 1.01
It did not fix the "no signal" issue but this one did support HDCP because it uses the Genesis gm5861H-LF processor vs gm5861-LF of the original board...

But then a few weeks ago I saw that a seller was offering the mainboard for a Acer X241W with firmware v1.02 & checksum: 0BEB
Based on the Acer service bulletin above it might still not be the right one, but I had to give it a try
It was installed just yesterday so it will be a long while until I know if it works or not since the issue is so intermittent.
I have attached both firmwares to this post
P.S: The X241W lacks the hardware for the speakers, I might just try to flash the board I bought a year ago and see if it works.
It was anyway time for a recap of it as you can see there is one bulging Teapo, great QC there Teapo: they all invariably fail eventually