Help disabling onboard Acer LA-E892P RAM

[shybear]

hi,
Acer Aspire A515-51G comes with onboard RAM (4GB) errors that doesn't allow install Windows in anyway (blue screen.)
On BIOS there isn't any set to disable the onobard RAM so actually I decided to soldered away the 4 RAM chip.

Right now without installed RAM on the slot the machine just power on and shut off soon next. With a RAM stick it power ON (0,6A) but black screen.
I've seen that for Asus boards there are some resistors to shift or maybe if its possible to modify BIOS so to make it possibile to BOOT just with RAM installed in the slot.
Actually I tried 4GB and 8GB tested RAM with no luck.

[piernov]

Re: Help disabling onboard Acer LA-E892P RAM

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[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

hi Piernov,
first of all really thanks for your fast reply!
From your picture and tab I've to set all RAM ID'S at 1.
So I think I've to add the two 10K smd resistors for each Id because I removed all chips.
The mounted chips has a logo of an M with an elipse on it so it make suppose its Micron chip then ID0 should be already at 1. Do you maybe have a boardview (or at least just a screnshoot) to find where these resistors are located? Thanks

[mcplslg123]

Re: Help disabling onboard Acer LA-E892P RAM

If you had MIcron as onboard memory, then your RAM_ID0 is already set to 1. So you need to make RAM_ID1/2/3 -all set to 1. In other words, RC150/153/224 has to be set and if RC155/225/226/227 are there, they have to be removed. I may be wrong but thats what i've understood. Without BV, its practically impossible to locate these resistors.

[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

I confirm that 4 memory chips are MICRON branded so as mcplslg123 says without memory chip I've RAM ID1/2/3 to be set to 1 as RAM ID0 that for Micron chips its already set to 1. I'll have next to check check if RC151 and RC155 are there or not and "copy" it to RC150 RC153 RC224 (looking@RC151) and RC225 RC226 RC227 (looking @RC155). I hope that Piernov may have boardview or at least a screenshoot picture to locate these resistors.

[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

Searching over the net I found schematic and boardview of LA-E892P rev.1A so I was to find on SDRAM_ID0 that:
RC151 is mounted
RC155 doesn't exist that its setting for state 1 (Micron chip installed).
So I changed the settings of ID1/2/3 from o to 1 in that way:
ID1 shift RC225 to RC150
ID2 shift RC226 to RC153
ID3 shift RC227 to RC224
I made it by solder and flux, NO AIR, checked for shorts and tested for right value of 10K between common point of RPC19 and each test point near CPU.
I attach also a microscope picture of the work.
Actually it looks like that there is something wrong because laptop doesn't power on at there is something that overheat maybe PU401. (around 0,2A)
I checked all again and I think to make the right resistors shifting.
I am also sure at all that I removed correctly RAM chips because before I checked and the laptop powered with onboard stick but no boot.
Maybe its because my board is REV: 1C but it seems that in this part of board is the same.

MOD Edit: Link to schematic -> https://www.badcaps.net/forum/showthread.php?t=123072

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[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

I'm really lost.
I tried to find for exact revision mainboard but anywhere there is just rev.1A.
Anyway comparing board layout with board view resistors and connections are exactly the same and the mounted resistors are all 10K.
Before to try to remove again resistors and see what's happen there are two strange things in schematic table that also Piernov posted.
1. in the tab the 4th line with no description comes with 0 0 1 1 what is?
2. there is an asterisk near RAM_ID0 and RAM_ID1 but I don't see any note about it into schematic.
Anyway I attach also a collage picture of works made and board.
I signed with an X where I moved RC225 RC226 and RC227.

[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

Next to last post I checked all again and next I plugin power and this time current was 0,01 - 0,02 and it power on .
Then I started installing windows without any problem but an hour later I found laptop shutdown. I tried to power on again but machine went in loops trying to start and next shut down.
Today I tried again and laptop at first worked but stopped again in like 30 minutes.
Then I checked again for some false contact on removed onboard ram chip and next I refreshed resistors solders trying to align it well.
Now @ cold machine power on but if I power off an on at 4th or 5th log comes with typical graphic chip problem and next start looping on/off but this is an other issue
So I want to thank piernov to show me the way how to set board and mcplslg123 to explain me how to do it and that works properly.
If someone has an other board version I think that schematic and boardview I posted.

[sadik35]

Re: Help disabling onboard Acer LA-E892P RAM

Please hep me send photo ram remove photo ?

[shybear]

Re: Help disabling onboard Acer LA-E892P RAM

Please hep me send photo ram remove photo ?

hi,
I advice you that its not easy to do it.
First of all you must have a microscope, a really good solder unit and an hot air station.

I suggest you to use gel flux instead of liquid one.
To remove it I suggest to mask around memory chips with kapton tape and do it one by one.
So first of all put some liquid flux under the chip and some gel flux all around the chip and use hot air moving it slowly on the chip. Don't try to force or do anything just wait and never stop the hot air over the chip. Just use something to push a bit the chip so you'll understand when chip is starting to desoldering then without moving hot air use a tweezers to take chip apart.

A suggestion: you've to be really patience to aim the desolder so don't give up or think you're dont' doing it right just give time to air to raise the right temperature.

[superhache]

Re: Help disabling onboard Acer LA-E892P RAM

Searching over the net I found schematic and boardview of LA-E892P rev.1A so I was to find on SDRAM_ID0 that:
RC151 is mounted
RC155 doesn't exist that its setting for state 1 (Micron chip installed).
So I changed the settings of ID1/2/3 from o to 1 in that way:
ID1 shift RC225 to RC150
ID2 shift RC226 to RC153
ID3 shift RC227 to RC224
I made it by solder and flux, NO AIR, checked for shorts and tested for right value of 10K between common point of RPC19 and each test point near CPU.
I attach also a microscope picture of the work.
Actually it looks like that there is something wrong because laptop doesn't power on at there is something that overheat maybe PU401. (around 0,2A)
I checked all again and I think to make the right resistors shifting.
I am also sure at all that I removed correctly RAM chips because before I checked and the laptop powered with onboard stick but no boot.
Maybe its because my board is REV: 1C but it seems that in this part of board is the same.

wow thanks a lot!!
it worked on an Acer A515-51 Mother LA-E891P REV 1A

[Puspendu Sikdar]

Re: Help disabling onboard Acer LA-E892P RAM

Thank you sir