THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

[Bartoloni]

the board model is:

LPN-1 TABLET MB
12H18-2
48.4WW01.021

Hi i have this laptop (i5 tablet+keyboard), there is an oscillator (OSC1) that reach 65°C (never seen something like that)
on the 4pin SMD surface of oscillator there is printed 0.0327 and 301 (with a symbol) , on 2 pins of the board there is 1.8V ..1 is ground and 1 is without any voltage (probably the output) .. the laptop is starting, fan is spinning fast there is a sync on external DP monitor but shows a black screen on both screens (the integrated one that is probably the faulty one that started the issue is also without backlight)

i found it watching heat on the opposite side (the oscillator is covered by heatsink)

thank you for any help and suggestion on how to replace (just to try) the oscillator... maybe with a different one.

P.S. the oscillator is near the chipset and i was thinking that there is a fault on the chipset (maybe customer replaced the screen with battery connected or something similar)

[Bartoloni]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

no one know who made this oscillator or how i can replace it with something different?

[anshad]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

no one know who made this oscillator or how i can replace it with something different?

As far as i know, schematic is unavailable for this board to this date. However if your goal is to find a replacement for that crystal, a schematic is not a must have. All you have to do is identify the CPU, find another board's schematic which uses the same CPU. Then you can find the Crystal's frequency and either buy a replacement or take from a faulty board (if one available)

[Bartoloni]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

This not a CPU but the Chipset, i searchend on ~100 boards that i have and oscillators are all 25Mhz 24Mhz 26Mhz and other Mhz vaues, this because a 32768 hz frequency is used (in a 16bit architectures) to create 1 second clock signal used by DATE/TIME of CMOS.. this kind of frequency is always (for what i can see this is confirmed except this motherboard) provided using a crystal (usb-drives... very old desktop motherboard) and not an oscillator... do you have an idea on how to replace a an oscillator by a crystal ? (i think this is not possible) and without the oscillator datasheet i can't do "experiments" without acknowledgment...

[anshad]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

This not a CPU but the Chipset, i searchend on ~100 boards that i have and oscillators are all 25Mhz 24Mhz 26Mhz and other Mhz vaues, this because a 32768 hz frequency is used (in a 16bit architectures) to create 1 second clock signal used by DATE/TIME of CMOS.. this kind of frequency is always (for what i can see this is confirmed except this motherboard) provided using a crystal (usb-drives... very old desktop motherboard) and not an oscillator... do you have an idea on how to replace a an oscillator by a crystal ? (i think this is not possible) and without the oscillator datasheet i can't do "experiments" without acknowledgment...

0.0327 marking i think means 0.0327Mhz, which is another way of denoting 32Khz. I think it's an RTC crystal. So far all the boards i have seen are using the same 32Khz RTC crystal. Old ones usually have the two pin, cylindrical version. This kind of four pin, SMD ones are common in newer boards. Two pins are actually dummy.

[Bartoloni]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

Two pins are actually dummy.

do you have an idea about placing a 2 legs crystal on this motherboard?
for what i found the 4 legs are usually.. GND - STANDBY(OR ENABLE) , VCC , CLOCK OUT

[anshad]

Re: THINKPAD helix LPN 1 TABLET MB 12H18-2 schematics request

do you have an idea about placing a 2 legs crystal on this motherboard?
for what i found the 4 legs are usually.. GND - STANDBY(OR ENABLE) , VCC , CLOCK OUT

My knowledge in the matter is limited. As far as i know, there are two kinds of oscillators that came in the 4 pin package. One is normal crystal with two functional pins, one GND and one NC. Usually they have pin 1 and 3 for crystal OSC pins, pin 2 as body GND and pin 4 not connected.

https://cdn.badcaps-static.com/pdfs/...1645366849.pdf

Two pin crystal can be used instead of this type.

Then there is the "Oscillator" package which has EN, Output, VCC and GND pins. According to specification, Pin 1 is NC/EN, 2 is GND, 3 is output, 4 is VDD. I haven't seen this kind yet and have zero experience with them.

It's hard to judge which kind is yours from the image. I believe checking pin 4 will get an answer. For a normal crystal, pin 4 is NC but for the OSC package, it's VDD which should be around 1.8v or higher.