SODIMM Socket - Which Pins are Chip Select?

[Mark & Mary Ann Weiss]

This question pertains to a Sony GRX560 notebook computer with a defective
SODIMM socket.

The condition only affects chip select (chip present?) at boot time.
Specifically, in order for the system BIOS to scan the installed memory
module, external downward pressure must be exerted on the module ONLY DURING
BOOT. Once the machine starts loading the OS, the module can be left alone.
PC continues to operate fine until next power off/on, at which time the RAM
module is not found unless downward pressure is exerted on it during boot
only.

Once the system is booted, it continues to run without incident and is able
to utilize the installed RAM.

This sounds like a poor connection with perhaps as few as one pin
connection.

My question is, on this 200-pin SODIMM socket, which pin carries the "chip
present" signal to the system mainboard?

There are simply too many pins for me to focus on all at once, but if I can
narrow down to the specific pin, perhaps I can effect a repair by bending
that pin outward a bit, or inserting a microscopic sliver behind it to add
spring tension to it.

Ultimate solution is to replace socket, which I would like to avoid, if at
all possible, due to the difficulty involved with SMD rework.

Any information on the pin functions of the socket?


--
Best Regards,

Mark A. Weiss, P.E.
www.mwcomms.com
-

 

[JW]

This sounds like a poor connection with perhaps as few as one pin
connection.

My question is, on this 200-pin SODIMM socket, which pin carries the "chip
present" signal to the system mainboard?

There's no "chip present, per se.

A datasheet is worth a thousand words:
http://download.micron.com/pdf/datasheets/modules/ddr2/HTF4C16_32_64x64HG.pdf

My guesses? Pins 195, 197, 198, 199, 200. Used for SPD functions during a
power up.

 

[Mark & Mary Ann Weiss]

There's no "chip present, per se.

A datasheet is worth a thousand words:
http://download.micron.com/pdf/datasheets/modules/ddr2/HTF4C16_32_64x64HG.pd
f

My guesses? Pins 195, 197, 198, 199, 200. Used for SPD functions during a
power up.

Thanks for the data sheet. I too happened across a similar sheet for a
different module, but same pinouts. These are the pins I suspected, but I
needed confirmation that they are indeed used only at boot time.

The symptom is a failure to detect both modules, unless someone presses on
the #1 module at POST/Boot time. Once past POST, the module can be let go
of, and the system will continue to run and use the RAM. Whatever it is,
it's only needed during POST and then not used, hence the broken connection
does not matter after that.


--
Best Regards,

Mark A. Weiss, P.E.
www.mwcomms.com
-

 

[JW]

Thanks for the data sheet. I too happened across a similar sheet for a
different module, but same pinouts. These are the pins I suspected, but I
needed confirmation that they are indeed used only at boot time.

The symptom is a failure to detect both modules, unless someone presses on
the #1 module at POST/Boot time. Once past POST, the module can be let go
of, and the system will continue to run and use the RAM. Whatever it is,
it's only needed during POST and then not used, hence the broken connection
does not matter after that.

Like I said, those would be the most likely candidates, they're only used
at power up to set memory timing. Any other pins would cause memory
failures/crashes.

 

[Mark & Mary Ann Weiss]

Like I said, those would be the most likely candidates, they're only used
at power up to set memory timing. Any other pins would cause memory
failures/crashes.

Thank you for confirming the affected pins.

I am going to open 'er up again this weekend and try retensioning those
pins, and also double-checking the soldering quality on the PCB that
connects to those pins.


--
Take care,

Mark & Mary Ann Weiss

VIDEO PRODUCTION . FILM SCANNING . DVD MASTERING . AUDIO RESTORATION
Hear my Kurzweil Creations at: http://www.dv-clips.com/theater.htm
Business sites at:
www.dv-clips.com
www.mwcomms.com
www.adventuresinanimemusic.com
-