Acer AL2423W Recapped, backlight works but no display

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

EDID-information can be read directly from U1 2402 on bus I2C without involvement of the processor.

Parable:
- What do you search under a lantern?
- The key has lost.
Where you have lost it?
- Yes on that road.
Why here you search?
-zdes is more light...

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Connected the monitor via VGA now to my Linux machine, in my first post I read the EDID data via DVI with GPU-Z, just wanted to see if it worked via VGA aswell...
And it does, no picture is displayed of course...

[root@localhost ~]# monitor-edid
Name: AL2423W
EISA ID: ACR0977
Screen size: 51.8 cm x 32.4 cm (24.05 inches, aspect ratio 16/10 = 1.60)
Gamma: 2.2
Analog signal
Max video bandwidth: 170 MHz

    HorizSync 31-81
    VertRefresh 56-75

    # Monitor preferred modeline (60.0 Hz vsync, 74.0 kHz hsync, ratio 16/10, 94 dpi)
    ModeLine "1920x1200" 154 1920 1968 2000 2080 1200 1203 1209 1235 -hsync +vsync

And the long verbose output if you want to see it...

[root@localhost ~]# monitor-edid -v
probing EDID using VBE (port 0)
 vbe: int 10h points to c000:0d18: 52 50 ba ca 03 ec fe c0
VBE version: 3.0, oem version = 4.52
Memory: 65536k
OEM name: NVIDIA
Vendor name: NVIDIA Corporation
Product name: NV34 Board - q231-0
Product revision: Chip Rev
Port 0:
 DDC1 not supported
 DDC2 supported
 Screen not blanked during data transfer
 Time to transfer one EDID block: 1 sec (rounded up)
parsing EDID from vbe
Name: AL2423W
EISA ID: ACR0977
Screen size: 51.8 cm x 32.4 cm (24.05 inches, aspect ratio 16/10 = 1.60)
Gamma: 2.2
Analog signal
Standard resolution: 640x480 @ 60 Hz (established timing)
Standard resolution: 640x480 @ 67 Hz (established timing)
Standard resolution: 640x480 @ 72 Hz (established timing)
Standard resolution: 640x480 @ 75 Hz (established timing)
Standard resolution: 720x400 @ 70 Hz (established timing)
Standard resolution: 800x600 @ 56 Hz (established timing)
Standard resolution: 800x600 @ 60 Hz (established timing)
Standard resolution: 800x600 @ 72 Hz (established timing)
Standard resolution: 800x600 @ 75 Hz (established timing)
Standard resolution: 832x624 @ 75 Hz (established timing)
Standard resolution: 1024x768 @ 60 Hz (established timing)
Standard resolution: 1024x768 @ 70 Hz (established timing)
Standard resolution: 1024x768 @ 75 Hz (established timing)
Standard resolution: 1280x1024 @ 75 Hz (established timing)
Standard resolution: 1920x1200 @ 60 Hz, ratio 16/10
Standard resolution: 1680x1050 @ 60 Hz, ratio 16/10
Standard resolution: 1600x1200 @ 60 Hz, ratio 4/3 (!)
Standard resolution: 1280x720 @ 60 Hz, ratio 16/9 (!)
Standard resolution: 1280x1024 @ 60 Hz, ratio 5/4 (!)
Standard resolution: 1280x960 @ 60 Hz, ratio 4/3 (!)
Standard resolution: 1152x864 @ 75 Hz, ratio 4/3 (!)
Standard resolution: 1440x900 @ 60 Hz, ratio 16/10
Max video bandwidth: 170 MHz

    HorizSync 31-81
    VertRefresh 56-75

    # Monitor preferred modeline (60.0 Hz vsync, 74.0 kHz hsync, ratio 16/10, 94 dpi)
    ModeLine "1920x1200" 154 1920 1968 2000 2080 1200 1203 1209 1235 -hsync +vsync

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

20 MHz it is enough. About waveform - a signal not periodic what can be the form - simply you observe activity of a signal in a big way no more Vcc for U8. If after short-term activity the signal disappears, the processor means has hung.

If the processor does not react to pressing of buttons it speaks that the processor does not work - or it is stopped because of program failure, or has broken. In this case business does not reach bus LVDS.

Look also at a reset signal on the processor, the reason in it can.

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

I should mention I have ordered the X1 crystal and the Teapo capacitor for position C147 that I did not have in stock (it sits right on the power line to the panel FYI...)

I got my small caps order from Elfa today
Swapped out C147; a 100uF 25v Teapo cap for Rubycon ZL, no difference
Swapped out the 14.318Mhz X1 crystal next, also no difference...

I guess next test will have to be with a scope, thanks for the clarifications ndugu!
Btw, what sort of waveforms should I be expecting to see sent to the LVDS PCB via CN5 cable?
And also on the flash chip, what sort of waveform should be present here?
The scope I'll be using will be max 20Mhz, will this be enough?

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

Yes, it is desirable an oscillograph

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

[QUOTE=Per Hansson;116676]Welcome to Badcaps and thank you very much for your post ndugu!
Did you have to use an oscilloscope to measure pins 2, 5 & 6 on U8?

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Here are my readings with multimeter;

#1, CE = Short blip at a volt or so then 0v
#2, SO = 3.325v
#3, WP = 0.971v
#4, VSS = GND
#5, SI = 3.313v
#6, SCK = Short blip at a volt or so then 0v
#7, HOLD = 0.967v
#8, VCC = 3.354v

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

говорите немношко по-русски?

Just kidding, - i have typed text above for 5 minutes (@US keyboard layout)

It's interested to see step by step solving this issue.
Good luck!

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Welcome to Badcaps and thank you very much for your post ndugu!
Did you have to use an oscilloscope to measure pins 2, 5 & 6 on U8?

-----------------------
Добро пожаловать в Badcaps, и благодарю Вас за Ваше сообщение ndugu!
Вы должны использовать осциллограф для измерения контакты 2, 5, 6 на U8?

[ndugu]

Re: Acer AL2423W Recapped, backlight works but no display

In processor GM5861H there is no internal memory of the programs, all program code is stored in SPI Flash SST25LF040. At monitor inclusion look on pinouts 2, 5, 6 microcircuits U8 go an exchange of the information or not. In my case, at power up there was a short-term activity (1-2 seconds), then the activity termination. It says with the big share of probability that the program code is deformed.

--------------------------
В процессоре GM5861H нет внутренней памяти программ, весь программный код хранится в SPI Flash SST25LF040. При включении монитора посмотри на выводах 2, 5, 6 микросхемы U8 идет обмен информации или нет. В моём случае, при влкючении была кратковременная активность (1-2 секунды), затем прекращение активности. Это говорит с большой долей вероятности о том, что искажен код программы.

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Thanks for the link dondrusco, but I'm not having much luck via Google to find similar instructions for my monitor
Do you know where the monitor stores the settings, is it in the SST25LF040A flash chip?

Because I asked for instructions on how to connect my programmer to the JTAG header but seems it is not possible at all
I wonder how the monitor would respond if it's eeprom was corrupt, this is my current theory...

I should mention I have ordered the X1 crystal and the Teapo capacitor for position C147 that I did not have in stock (it sits right on the power line to the panel FYI...)
Btw, the power to the panel, is it supposed to be 4.9 (5v?) I can't seem to find this info in the service manual...

> Hi, I've got a GQ-4X with a ADP-056 adapter
> I would like to read the firmware via JTAG on an Acer AL2423W monitor
> It has a Genesis chip on the logic board, and the EEPROM is a SST25LF040A
>
> I have attached the pinout of the 6-pin header from the service manual,
> how do these map to the ADP-056?
>
> I think I have a few figured out, but not sure;
>
> J1> ADP-056
> 1 > ?
> 2 > ?
> 3 > TDO
> 4 > TDI
> 5 > TCK
> 6 > TMS
>
> Sincerely - Per Hansson

Hi,

Thanks for the email.

The GQ-4X supports CPLD programming via JTAG.

Your chip SST25LF040A is not a JTAG chip, it is a SPI chip.
If yo want to read,write this chip via JTAG connection, then you need a
customized JTAG device. The GQ-4X does not work that way.

If your mother board has a SPI port, then you can try to programming the
chip via SPI port. Otherwise you need to remove the chip from mother board
and programming it on the programmer directly.

Regards.

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

The last thing, which comes to me, is reset flash eeprom to default settings.

But I have never done it before...

See https://www.badcaps.net/forum/showpo...71&postcount=7

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Hi, I finally managed to get the metal cover off the LVD board
There was one fuse I could identify, F1
It reads 4.9v on both sides to ground...

Actually I am reading ca 0.8 > 1.5v on the data pins of CN5 with my Fluke 113 DMM in manual voltage measuring mode (I do not use auto mode because it is dangerous)

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

OK, I found, that resistors are NC. (in the schema)

You have to trace that grey, magenta and blue wire to the panel board.
There is one SMD fuse just behind LVD to protect panel.

If there is voltage behind the fuse, we have to return back to Genesis chip.
You have to have oscilloscope to detect signals @ data pins of CN5.
If there is no signal - then panel is OK, control chip is probably dead.
Otherwise, the panel is probably dead.

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

Did some further tracing of pins 26 and 27 on CN5 that showed zero volts
Turns out they have been left out of the circuit at installation
R152 & R164 that connect to pin #27 are missing
R150 & R163 that connect to pin #26 are missing

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

U12 = double checked, voltages still same as this post
Pin 1 was slightly lower, but if I understand the schematic right this is a control loop voltage, so it will be different depending on how much load is on the system (how hard U12 is having to work to produce a clean 3.3v output)

C196 = 3.356v

Q10 = Emitter=3.352v, Base=2.602v, Collector=0v
 Q9 = Emitter=3.352v, Base=2.582v, Collector=3.256v
 Q8 = Not installed

These transistors has these markings (the "44" is written 90° in relation to the other text)
R2A 44

I think this is the correct PDF;

I attached a cropped picture of the relevant section, it is also available in full resolution version; https://www.badcaps.net/forum/attach...1&d=1399820456

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

You can also check 3,3_DVDD @ emitors of Q8,Q9,Q10. If there is no voltage, you probably cut the line under C196 during exchange. It is power for keyboard and LEDs, too.

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

There is no voltage @26 and 27 pins. Check U12 and capacitor C196. +3,3_DVDD line

[Per Hansson]

Re: Acer AL2423W Recapped, backlight works but no display

dondrusco; do you want me to measure on the underside of the LVD board (the board I pictured in the previous post?)
If so it would need to be disconnected from the panel when measuring... If you just want me to measure where the cable connects to the LVD can't I just measure where it goes out from the logic board instead?

That is what I did, I measured at the outputs on the logic board, i.e. connector CN5 on the logic board, also visible in the bottom of the picture in my previous post...

These where the results;
30=4,9v
29=4.9v
28=4.9v
27=0v
26=0v

[dondrusco]

Re: Acer AL2423W Recapped, backlight works but no display

Use diagram 02. SDRAM/AMP/OUTPUT - CN5.

Follow wire colors from PCB to LVD and check voltages there.
I expect problem - pins 26,27, 28 and 30 - 3,3V