Toshiba A205-S5825 regular shut down at start up

Mohamed Kamel
13/05/2014 21:41
Hi! An urgent help is needed for Toshiba A205-S5825 regular shut down issue.
Platform : ISKAA LA-3481P Rev : 2A

Steps already taken :

1-cleaned fan system (was a little dusty but not clogged), removed dried paste and applied new one to CPU and GPU.

2-Tried naked mobo with a working ram, CPU, KB and Lcd display, enter bios screen, lap always shut down after about 1'50s.

3- Scanned mobo with an infra-red thermometer, Max temperature registred 42° at SB, so no heat issue.

4- Checked Thermal Sensor ADM1032ARM :
VDD : 3Vs
D+ 2.38V
D- 0v
EC_SMB_CK2 and _DA2 : 5.6V each
pin 4 "Therm#" and 6 "Alert#" not connected.

Please note that CPU of A205-S5825 series doesn't use big "Nec-Tokin cap" but 330uf small caps.

Also Tried with Mobo +ram +fan but without CPU it also shut down at about same time.

Has any one dealt with the same issue, or any clue as where to dig further

Thank you

Sergej
14/05/2014 00:52
Mohamed Kamel, only from power supply? Try to change PQ34, PQ37

Mohamed Kamel
16/05/2014 17:02
Sergej писал:
Mohamed Kamel, only from power supply? Try to change PQ34, PQ37


Found G/S resistance of PQ34 and PQ37 almost 0 ohms. Replacing both,
didn't help and G/S resistance remained 0 ohms.

Replaced ISL6262A with no avail and surprisingly G/S resistance is always 0 ohms.

My questions :
1*- Why G/S resistance of PQ34 and PQ37 is still 0 ohm ? That might be a clue.
2*- But as I tried Mobo +ram +fan but without CPU and still shut down issue, I'm more likely to conclude that fail is either in input supply of ISL6262A or other DC/DC converts involved when powering lap.

Wish to get your comments on the 2 above mentioned points and any new suggestion as where to dig further is welcome.

If schematic or particular part of it is needed p.s ask.

thanks.

Mohamed Kamel
27/05/2014 01:02
The problem of Toshiba A205 shut down is still outstanding, will appreciate any new suggestion to help solving the issue.

Also any comment from Sergej or other members on the 2 points raised on my last post is welcome and might put new light on the issue.

Mikkey
17/06/2014 16:24
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