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Old 04-28-2012, 03:23 AM   #1
primoz1
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Default Acer aspire 7520 power problem

Hi again. I got this laptop with integrated nvidia graphic on board, I reball GPU about month or two back ago, and then work OK. Now has a problem, work if has battery and AC power is connected, but just first time if I shut down laptop and try switched on again (with power button) then not react at all, but if pull out AC connector and put back, then work again, if I try started without battery and AC power connected, no react again.

Laptop (when started) works OK.

What colud be wrong ? AC adapter is OK, even I try with another adapter who is 100% OK. but no changes.
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Old 04-29-2012, 08:04 AM   #2
xaviero1412
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Default Re: Acer aspire 7520 power problem

try update bios first...
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Old 04-30-2012, 03:29 AM   #3
primoz1
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Default Re: Acer aspire 7520 power problem

Hi. I update bios from windows, and no changes. Once try start without battery in this way, unplug power and remove battery and hold power button app. 60 sec, then with pushed power button, connect power plug, release and push again power button and laptop started, but when I try again no work. So this laptop only start with battery, after start can plug power and work normal.
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Old 04-30-2012, 01:14 PM   #4
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Default Re: Acer aspire 7520 power problem

it just probably guests,
1. check vccore
2. check vdisp

i think that 2 voltages are priority to check first after doing update bios and no any progress
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Old 04-30-2012, 01:51 PM   #5
primoz1
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Default Re: Acer aspire 7520 power problem

Quote:
Originally Posted by xaviero1412 View Post
it just probably guests,
1. check vccore
2. check vdisp

i think that 2 voltages are priority to check first after doing update bios and no any progress
Hi what do you mean with this vccore and vdisp ?
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Old 04-30-2012, 03:34 PM   #6
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Default Re: Acer aspire 7520 power problem

vccore is cpu core voltage
vdisp is display/VGA voltage
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Old 04-30-2012, 03:47 PM   #7
primoz1
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Default Re: Acer aspire 7520 power problem

Aha, how can I do this test ? With some software or multimeter ?
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Old 04-30-2012, 03:56 PM   #8
xaviero1412
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Default Re: Acer aspire 7520 power problem

at this state, u cant check via s/w.
u must check with multimeter voltage reading through hardware.
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Old 04-30-2012, 04:26 PM   #9
primoz1
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Default Re: Acer aspire 7520 power problem

Ok. But how can I do this, because Im not familiar with multimeter ?
Thankyou.
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Old 04-30-2012, 04:48 PM   #10
xaviero1412
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Default Re: Acer aspire 7520 power problem

sorry , i cant tell you any further since u not familiar with metering-job... i'm afraid u will damaging ur precious laptop....

please, take some any basic electro class or u can search n learn online... utube n google is your friend...
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Old 04-30-2012, 04:54 PM   #11
primoz1
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Default Re: Acer aspire 7520 power problem

Hi. I can use multimeter, but I don know what on motherboard must check, with that part I do not have much experience, that I try to say.
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Old 04-30-2012, 05:21 PM   #12
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Default Re: Acer aspire 7520 power problem

check power coil (PL) voltage near the processor and southbridge or VGA
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Old 05-01-2012, 08:38 AM   #13
primoz1
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Default Re: Acer aspire 7520 power problem

Hi I hope Im measure correct elements (cube coils)

I must say first I try ohm conductivity for each coil , then I connect battery and power plug and turn on motherboard, and check voltage of coils, black wire tester I put on minus like on pictures, and rapid lost voltage on this coils.

I try first with battery and then remowe battery and result is the same.
Attached Images
File Type: jpg ohm-with-no-power.jpg (617.7 KB, 217 views)
File Type: jpg voltage.jpg (657.2 KB, 196 views)
File Type: jpg multimeter-settings.jpg (130.1 KB, 124 views)
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Old 05-01-2012, 10:06 AM   #14
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Default Re: Acer aspire 7520 power problem

Quote:
Originally Posted by primoz1 View Post
Hi I hope Im measure correct elements (cube coils)

I must say first I try ohm conductivity for each coil , then I connect battery and power plug and turn on motherboard, and check voltage of coils, black wire tester I put on minus like on pictures, and rapid lost voltage on this coils.

I try first with battery and then remowe battery and result is the same.
measure it with and with-out processor, and always write it down....
check voltage on red-pointer, especially the coil nearest processor.
it its lower than 1v, replace the blue-checklist with 2.5v 470uf caps.

the yellow-checklist will not be replace if the above 4caps 470uf has solve the problem
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File Type: jpg acer7520.jpg (395.1 KB, 251 views)
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Old 05-01-2012, 11:05 AM   #15
primoz1
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Default Re: Acer aspire 7520 power problem

Hi I check again without CPU and get this values.

I search this 470 uf capacitors.
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File Type: jpg aspire-7520g.jpg (629.3 KB, 237 views)
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Old 05-01-2012, 11:35 AM   #16
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Default Re: Acer aspire 7520 power problem

so, positive 100% the problem is at cpu_core/vccore.... just replace the 4caps....
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Old 05-01-2012, 11:58 AM   #17
12ax7a
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Default Re: Acer aspire 7520 power problem

your black dvm lead may be in the wrong hole for measuring ohms & voltage... although some voltages do seem legit.. that 10A hole is usually for current only. normally you'd use the COM hole for those measurements. too fuzzy to read the meter writing from here. just something to check.
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Old 05-01-2012, 01:42 PM   #18
primoz1
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Default Re: Acer aspire 7520 power problem

Hi. I replaced all 4 capacotors. Now sometime start without battery just pliged on AC power, sometime not, if once start, then can turned ON and OFF with power switch, but just 5-6 times, then wont start again, but with battery start OK. If I found another 7520 board I will try change yellow element too, this 4 capacitors I grab from 5520g with damaged southbridge pins (puled out from board) but 5520g not have this yellow element.

I will report what happend, thank's for help.
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Old 05-02-2012, 09:15 AM   #19
xaviero1412
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Default Re: Acer aspire 7520 power problem

replace them with new capacitor, not from damage boards.
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Old 06-10-2012, 11:06 AM   #20
primoz1
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Default Re: Acer aspire 7520 power problem

Hi thanks for all, I change two capacitor with new and now is all OK.

But I got another acer aspire 5520 with graphic on card, but no show any picture, I try with another graphivc card and still no changes. So I measure coils on similar spots like on 7520 and get this voltages.
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File Type: jpg 5520g.jpg (384.9 KB, 177 views)
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