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Acer aspire 5738Z dead laptop

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  • Автор: mohkamtun
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Hello
Got dead Acer aspire 5738Z for repair.
Platform : JV50-MV M92MB (discrete)

Found shorted VGA_CORE_PWR, changed U41 and short was gone.

Now lap powers up, leds lighting, fan spinning but absolutely no display (neither on screen nor on external monitor).

All main system voltages are ok

Checked LCD1 (lcd connector), DCBATOUT_LCD1, LCD_TXACLK+ and LCD_TXACLK- are ok, but BRIGHTNESS_CN, BLON_OUT_1 and LCDVDD are all absent!

Dumping bios with last version "BIOS_Acer_1.34_A_A" did not help.

*Did anyone encounter same display problem with aspire 5738Z?

*Does aspire 5738Z has graphic chip issue ?

*Any suggestion as to help solve display fail should be appreciated.

Thank you

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2

  • Автор: freeqwer
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post code ?

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  • Автор: mohkamtun
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freeqwer написал(а):

post code?

88

Is it bios initialization problem ? If so what steps to take ?

According to some search on the web, bios is likely to be Phoenix, but not sure.

Is there any secure way to find out which bios has a laptop, when display is failing ?

Thank you

Отредактировано mohkamtun (28.04.2015 01:17:46)

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4

  • Автор: freeqwer
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What is the voltage on the CPU and GPU ?

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  • Автор: mohkamtun
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freeqwer написал(а):

What is the voltage on the CPU and GPU?

Hello,
Don't know what happens, my yesterday post disappeared, might have pushed by mistake a wrong button!

Ok, then try to summarize again :
Voltages found :
VCC_Core : 0.98V
but surprisingly, VGA_Core : 0V ?? though shorted U41 already changed.

Checked working conditions of U45 :
VDD : +5V
TON : +0.9V ??

P.S note that BOOT is +5V

1*-Think TON isn't correct, isn't it ???

Changed U45 RT8202 to RT8204 at hand, to no avail : always no voltage output and TON remains +0.9V

Lifted one side of L19 and measured resistance to gnd :
-before L19 : over 6Kohms
-after L19 : 3 to 4 Ohms ?

2*- 3 to 4 Ohms is correct for VGA_Core output,or is it too low ??

3*-What's next step to take to solve VGA_Core output fail ?

4*- As VGA_Core is failing, and for further diagnose, is their any risk to supply temporarily +1V to VGA_Core output with L19 removed and power up lap as to see whether it'll display once GPU voltage is solved.

Thank you

Отредактировано mohkamtun (30.04.2015 00:43:54)

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hello !

I should be grateful to get clarified my last 4 pending questions so as to help me move on the right direction in repairing Acer 5738Z.

Add to my post 5, working conditions of U45,  EN_VGA=+3.3V

Thank you

Отредактировано mohkamtun (01.05.2015 19:30:33)

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7

  • Автор: freeqwer
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mohkamtun написал(а):

TON : +0.9V ??

Check the value of the resistor R418
Check the value of the capacitor С696

mohkamtun написал(а):

-before L19 : over 6Kohms

this is a normal value

mohkamtun написал(а):

-after L19 : 3 to 4 Ohms ?

this value can be (for the GPU)

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  • Автор: mohkamtun
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freeqwer написал(а):

Check the value of the resistor R418
Check the value of the capacitor С696

R418 and C696 are already checked OK : Resistor checked in circuit and C696 out of circuit.

Wish to precise, when adapter is connected Ton is +19V, It goes to +0.9V when lap is powered on.

I have some doubt regarding the replacement of U45 RT8202 by RT8204, which I got at hand though pinout is likely to be same.

Hi, new feed back
Changed again U45, and both U40 and U41 with 2 replacements fets, always no VGA_Core output but RT8204_DL_VGA is +3V instead of 0V (open) and RT8204_DH_VGA is 0V.

OUTPUT is then flowing through U40 instead of going through coil ?

Don't understand why it's happening ? :smoke: wish to identify culprit component;

Please suggest any further step to take.

Thank you

Отредактировано mohkamtun (04.05.2015 21:18:11)

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9

  • Автор: freeqwer
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mohkamtun написал(а):

I have some doubt regarding the replacement of U45 RT8202 by RT8204

I also have such doubts :
http://sh.uploads.ru/t/gFUHb.jpg
http://sg.uploads.ru/t/PW8SF.jpg

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  • Автор: mohkamtun
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freeqwer написал(а):

I also have such doubts:

Hi everyone!
Finally, got a recovered RT8202 but always no VGA_CORE output

After deep diagnostic, conclude that bad load on VGA_CORE_PWR line is preventing  issue of +1.05V .

Probably a cap on the output line is leaky ?

1*-Need diagram JV50-MV [b]M92MB[/b] as I got at hand JV50_MV_-1_0109, which is slightly different from mobo.
2*- Using DC supply voltage to identify leaking cap didn't help, is there any quick way to  find faulty component on VGA_CORE_PWR line ?

thank you

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  • Автор: freeqwer
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Write more than simple sentences.
I don't always catch the meaning.

mohkamtun написал(а):

Need diagram JV50-MV

LINK

mohkamtun написал(а):

After deep diagnostic, conclude that bad load on VGA_CORE_PWR line is preventing  issue of +1.05V .

What is the relationship between the signals ?

What is the resistance of the line VGA_CORE_PWR ?
Check U40 u41 u17

What are the voltage across the terminals  U45 :

16 TON
15 EN/DEM
2 VDD
9 VDDP
13 BOOT

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12

  • Автор: mohkamtun
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freeqwer написал(а):

Write more than simple sentences.
I do not catch the Meaning Always.

I will try to make it more clear.

freeqwer написал(а):

LINK

The acer under repair is Platform: JV50-MV M92MB (discrete) PCB P/N : 48.4CG07.011, the link is for JV50_MV, PCB P/N : 48.4CG01.0SA, which is slightly different. 

freeqwer написал(а):

What is the relationship between the signals?

I didn't understand exactly what you mean.

freeqwer написал(а):

What is the resistance of the line VGA_CORE_PWR?
Check U40 U41 U17
What are the voltage across the terminals U45:

16 TON
15 EN / DEM
2 VDD
9 VDDP
13 BOOT

Resistance of line VGA_CORE_PWR is 5 to 6ohms.
U40, U41 already changed and are ok. U17 doesn't exist in mobo.

Voltages across terminals of U45 are :

16TON : +19V
15 EN /DEM : +3.3V
2 VDD and pin 9 VDDP : +5V
13 BOOT : +5V

After deep diagnostic of U45 and it's surrounding components, I came to the conclusion that something on the output rail of VGA_CORE_PWR is preventing +1.05V to be issued.
It should be one of the multiple parallel caps attached to VGA VDD supply pins.

That's why I need the right scheme i.e JV50-MV M92MB (discrete) PCB P/N 48.4CG 07.011 to identify the culprit cap.

1*-If you have any download link for this platform, I should appreciate.
2*-Is there any quick and sure method to find out the leaky cap WITHOUT REMOVING EVERY CAP ON VGA_CORE_PWR LINE ?

Thank you

Отредактировано mohkamtun (27.05.2015 18:19:08)

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