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Old 08-10-2018, 05:07 AM   #1
robgerr
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Default Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

Goodmorning friends of the forum. This laptop has isegent defects:
When I give power on it does not react,
I have to make several attempts until that main power up.
I have no image on both lcd and vga screens.
I noticed that it warms up the pch.
The tensions seem to be there in the coils except that of the cpu (cpu_core) that are missing.
I tried to exchange the cpu but nothing.
I tried to reprogram the bios with dumps found on the net but nothing to do.
I did a reflow on the NVIDIA bga but nothing.
Also changed the ram but nothing
The resistance on coils with inserted cpu and 12 Ohm, I think it is correct.
The thing that leaves me perpplesso and that pch warms up a lot and does not seem normal.
Since I do not have printing on the board it is difficult to follow the diagram but I have measured near the pch of the capacitors and I find a resistance of 3ohm which seems to me low.
I checked on U511 at pin 7 and I find 3V.
Thank you
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Old 08-10-2018, 10:12 AM   #2
caspian
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

It is possible that the PCH is faulty. It is also possible that the CPU-VCore circuit is faulty.
Anyway, you need the schematic of this laptop.
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Old 08-10-2018, 11:35 AM   #3
piernov
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

If it's the PCH and not the GPU, 3 ohms would be too low.
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Old 08-10-2018, 05:34 PM   #4
robgerr
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

I measured the voltage in the capacitors where I find the 3 ohm and when I give the power on I find a voltage of 1.05v in these capacitors
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Old 08-10-2018, 10:38 PM   #5
mcplslg123
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

If you have schematic, Then fiest check VR ON signal is present or not on kbc as well as vcore ic. Next you need to check voltages on all pins of vcore ic.
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Old 08-11-2018, 03:32 AM   #6
robgerr
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

yes I have the scheme. Tomorrow I take note of all the tensions on the IC that produces the vcc core
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Old 08-11-2018, 07:01 AM   #7
robgerr
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

schematic:
https://we.tl/FwkUvd0jE3
U511 -iSL95831AHRTZ-T VOLTAGE:
pin 1 0v
pin 2 0v
pin 3 0v
pin 4 1,05v
pin 5 1,05v
pin 6 1,05v
pin 7 3,11v
pin 8 0v
pin 9 0v
pin 10 1,05v
pin 11 0,67v
pin 12 3,47v
pin 13 3,30v
pin 14 0v
pin 15 0v
pin 16 0v
pin 17 0v
pin 18 0v
pin 19 0v
pin 20 0v
pin 21 0v
pin 22 5,08v
pin 23 19,25v
pin 24 0v
pin 25 4,77v
pin 26 0v
pin 27 0v
pin 28 0v
pin 29 0v
pin 30 5,09 v
pin 31 5,09 v
pin 32 0v
pin 33 0v
pin 34 0v
pin 36 0v
pin 36 4,77v
pin 37 0v
pin 38 0v
pin 39 0v
pin 40 4,82v
pin 41 0,11v
pin 42 3.55v
pin 43 5,09 v
pin 44 0,8v
pin 45 0,v
pin 46 0v
pin 47 0v
pin 48 0v
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Old 08-11-2018, 12:33 PM   #8
caspian
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

replace U511 and Q513 and Q512 and Q515 and Q514 at the same time if you have got spare ones. this may solve the issue. Although I am not sure this will fix the problem, but this is the best work you can do now.

Last edited by caspian; 08-11-2018 at 12:40 PM..
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Old 08-13-2018, 04:55 AM   #9
robgerr
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

thank's caspian

I found iSL95831 instead of iSL95831A but reading on other forums I saw that it worked on this board. Unfortunately I did not have the mosfet, I soldered ISL but still nothing, I do not have the cpu_core
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Old 08-13-2018, 08:56 AM   #10
caspian
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Default Re: Samsung RV520 (main BA4-01608A Scala2_R) no video and no cpu_core

Now, remove Q513 and Q512 and Q515 and Q514 from the board the test them separately using your multimeter. then while the mosfets are removed, check voltages on all pins of U511. It takes time to reach a successful repair step by step.
have you soldered U511 properly?

Last edited by caspian; 08-13-2018 at 09:24 AM..
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