T23 4x beep with any (working) RAM, 1-3-3-1 without RAM

[RealBlackStuff]

An old problem, that was never satisfactory solved, has cropped up again.
T23 beeps 4x (1-1-1-1) regardless of whatever 64/128/256/512MB module is put in either or both RAM-slot(s).
All used modules are tested working and all are PC133.
Without any RAM, if beeps (correctly) 1-3-3-1.
At boot-up the fan spins for a few seconds, then switches off.
CMOS is good (3.1V).
From what I can see all inductors are properly mounted.
Both modem and LAN cards have been removed, no HD or CD or main battery.
Any suggestions?

[rkawakami]

Swap out/re-seat the CPU?

[RealBlackStuff]

Tried that, but no good, unfortunately.
Swapped out keyboard, CMOS, main battery, charger, no difference.
Rather than dump that T23, I bought another motherboard cheap here: http://www.primelec.com/ibm-lenovo-thin ... nWVCGepXGg
Will let you know next week how that goes.

[MikalE]

Has the MB been inspected for cold connections on the RAM slots?

[RealBlackStuff]

Yup, all contacts have been resoldered, unfortunately to no avail, hence the new mobo.

[MikalE]

Is it possible that the northbridge has failed?

[RealBlackStuff]

I can heartily recommend that Primelec mobo, it's an officially refurbed T23 12P3770 mobo!
All I needed to do was use the HMD to correct the MTM/SN and install the latest 1.20 BIOS, it already had 1.06a EC.
To make the laptop a bit more attractive, I also gave it my lid fixer-upper treatment.

BTW, any of you own a Bimmer or Merc?
T23 is ideal for servicing them, since they have a Serial Port.
(And if interested enough, I might sell...)

[rkawakami]

BTW, any of you own a Bimmer or Merc?

2000 BMW E46 (323i). I use an ODB II USB interface cable; no serial port needed.

[kfzhu1229]

Yup, all contacts have been resoldered, unfortunately to no avail, hence the new mobo.

Since you have nothing to lose by now, try washing the motherboard? Sometimes that helps.

[RealBlackStuff]

To be honest, I got better things to do...