Support in other languages: 
Showing results for 
Search instead for 
Do you mean 
Reply
Community Moderator
richk
Posts: 2,489
Registered: ‎01-01-2010
Location: San Francisco
0

Re: T400 motherboard replacement advice needed?

[ Edited ]

See my note above about high temperatures. You need at least a quartz preheater and a good rework station (plus steady hands).  The bigger fuse (3.18mm) is Littelfuse 433003 (3 amp, 32 volt).  The smaller one (1.6mm)  is Littlefuse 434500 (.5 amp 32 volt).  I don't know a good source. Sometimes they are available at Mouser.com.  I use organ donor boards if I fix them.

Community Moderator
zoltanthegypsy
Posts: 3,462
Registered: ‎01-13-2008
Location: Bainbridge Island, WA, USA
0

Re: T400 motherboard replacement advice needed?

[ Edited ]

Is there enough room to do something really tacky like bridging the blown surface-mount fuse with a leaded one? (leeeeeded, not led-ed)  Using low-temp non ROHS solder?

 

Pretty shade-tree, but maybe in an emergency?  Kids, don't try this at home.  I'm asking, not saying...

 

Z.


The large print: please read the Community Participation Rules before posting. Include as much information as possible: model, machine type, operating system, and a descriptive subject line. Do not include personal information: serial number, telephone number, email address, etc.

 

The fine print: I do not work for, nor do I speak for Lenovo. Unsolicited private messages will be ignored. ... GeezBlog

English English Community   Deutsche Deutsche Community   Español Comunidad en Español   ru.gif Русскоязычное Сообщество

Community Moderator
richk
Posts: 2,489
Registered: ‎01-01-2010
Location: San Francisco
0

Re: T400 motherboard replacement advice needed?

There is room
Fanfold Paper
x_merlin_x
Posts: 13
Registered: ‎12-30-2008
Location: Munich, Germany
0

Re: T400 motherboard replacement advice needed?

Hi richk and everybody,

 

I am having a similar problem with my T500. Backlight not working while everything else is fine. I seem to have blown it during the replacement of the magnesium display frame.

 

Where exactly can I find the fuse F7 labeled as a P. I have removed the keyboard and the front plastics. Do I have to remove the bottome plastics as well?

What's DOS?
pavanbabut
Posts: 5
Registered: ‎05-15-2010
Location: Fremont, CA, USA
0

Re: T400 motherboard replacement advice needed?

My T400 started this when I am trying to replace the LCD with another one. The new one came with its own inverter so I installed it and plugged in everything and turned on the system and screen is soo dim that you can barely see it and none of the lights come on except the WiFi.

 

I swapped the inverter with the old one that was working fine before and the staus is still the same, no leds except WiFi and display is dim (even using old LCD that has scratches on it and was working 100% funcationally before)

 

I looked under the LCD connector on the board and I saw two conponents right below the connector one towards optical drive (labels P and green in color) and another one towards the CPU (labeled F, aslo green in color). They look fine to me cosmetically, will check their continuity tomorrow.

 

Meanwhile if you guys have any suggestions, let me know. 

What's DOS?
pavanbabut
Posts: 5
Registered: ‎05-15-2010
Location: Fremont, CA, USA
0

Re: T400 motherboard replacement advice needed?

[ Edited ]

The tested both fuses and the big one appears to be fine as it has continuity, but the small one doesn't. This doesn't make sense why my backlight is also not working on both screens that I have unless I am looking at a wrong fuse.

 

I have highlighted the fuses that i am checking in the picture below. The one on the right appears to be fine, but not the one on the left.

 

Link to image

 

Any ideas?

 

Moderator note: images totalling more than 50k converted to links per forum rules:  Lenovo Community Participation Rules

Community Moderator
richk
Posts: 2,489
Registered: ‎01-01-2010
Location: San Francisco
0

Re: T400 motherboard replacement advice needed?

If those fuses are not both good, you will have the problem you describe
What's DOS?
pavanbabut
Posts: 5
Registered: ‎05-15-2010
Location: Fremont, CA, USA
0

Re: T400 motherboard replacement advice needed?

I ordered a couple of new inverter boards to see if its the problem that caused the fuse to burn in the first place. Will keep the status updated as I get them.

 

thanks

What's DOS?
pavanbabut
Posts: 5
Registered: ‎05-15-2010
Location: Fremont, CA, USA
0

Re: T400 motherboard replacement advice needed?

Turns out that replacing just the small fuse fixed both issues.. status LEDs and backlight. Now they both are working.

 

So, having a bad small fuse is enough to have both these issues.

Community Moderator
richk
Posts: 2,489
Registered: ‎01-01-2010
Location: San Francisco
0

Re: T400 motherboard replacement advice needed?

As I said "If those fuses are not both good, you will have the problem you describe."