~Toughbooktalk~ Rob - 630-300-8877

The largest Toughbook discussion site on the net!
It is currently Fri Jan 18, 2019 4:37 pm

All times are UTC-06:00

Post new topic  Reply to topic  [ 1 post ] 
Author Message
PostPosted: Sat Oct 25, 2014 7:12 am 
User avatar

Joined: Fri Jan 18, 2013 11:35 am
Posts: 2969
I will just cut and paste the highlights from NBR.....


First of all i would like to say Hello to everyone as i have been lurking about looking at several posts on this forum over the last year.
Well now the problem i have, its a CF-52 MK3 with a backlight problem (i.e it doesn't work), I bought this cf-52 with a broken screen and was assured that everything else worked o.k only to replace the screen and find out that either the led inverter is not working or their is a problem coming from the MB.
I dont have any workshop manuals for the cf-52 mk3, just pdf's and driver's for the cf-52 mk2 which i also have. Did think i could swap screens with my mk2 untill i found out the mk3 uses a led backlight and the inverter's/cables are completely different. I dont seem to be able to find a part number fror this mk3 inverter or any way that i could test it, i would like to know if anyone has had this problem and if they have pin out diags for the cables or manuals for the mk3 cf-52 all would be appreciated.
Regards to all Billyhl.

LED-screens have inverters too :) but with a lower voltage.
But I don't believe, that he has an LED-driven backlight, except someone else has done the same, like I had done myself to change the CCFL into LED on his machine.
@billyhl: Could u pls post a pic from ur inverter and tell us ur full model number? The connector to the mainboard could be different. But the inverter itself should be the same.


Part number for the inverter is


If your 52 has had a crunch the fault may not be with the LED Driver PCB itself but with a fuse on the main board. Given an understanding of multimeter use, ESD precautions & electrical safety it's at least worth a look with a magnifier and a torch.

Laptops have a number of surface mount fuses, mostly on the main board, often close to the connector leading to the protected circuit. I don't see any on your LED Driver board.

Suggest finding all the images you can online of SMD fuses (surface mount device) so you can distinguish them from other components. They're frequently marked on the board as F--- for fuse. Diodes are D---, resistors R---, capacitors C--- etc.

This is a great Call....Great advice. These surface mount fuses are tough to see with over 40 eyes. I had a 51MK3 with no LCD backlight. The LCD worked in other units and a external monitor worked too.

I had the MB out in my hand with one eye and a magnifying glass and found a blown surface mount fuse.

This photo is a 51MK2 MB surface mount fuse.

The screen was missing from the cf-52 when i bought it but i messaged the user who told me that the old screen had the number LP154WX7 (TL)(P2) on the back of it, apparently there are several different connections on these and the one i got from a certain uk auction website was item number 370648399712 which stated "NEW 15.4" LED Screen LP154WX7(TL)(P2) or equivalent compatible BLOCK Connector", I had provided them with pictures from the LED Driver PCB and this was the screen that was suggested for this cf-52. Hope this helps onirakkiss, and thanks for your input.

Regards to all Billyhl.

Thank U, thats what I want to know.
Here LP154WX7-TLP2 Datasheet download - Panelook.com U will find some more specifications, especially interesting are the:
Lamp Voltage : 20.3/22.4/23.8V (Min./Typ./Max.) (thats why u need an inverter to stepup from ur battery voltage)
and the LED Interface Pins : 12 pins
Pin Configuration : BLE-12PINS-ACACACACACAC

just switch the machine on and check the voltage against the chassis on every single pin on the 8pin-connector, which will power up ur backlight. But be really carefully, cause if u short the wrong pins with ur multimeter, another fuse will be blown, or something else.

The third connector is for the touchscreen.

I might be jumping in a bit late. I have found the the CF-52 MK3 has a big problem with the screens. I have three sitting here with the same problem. Blank screen but good output on the VGA connector. In every case it is not the screen, inverter nor the fuses. It is two very small sma devices. One is a OR gate and the other is a AND gate. In all three cases, these two chips are bad. I have been super busy with other projects and haven't had a chance to touch those in some time but hope to get back to them soon.

How do u know, that the LED-inverter is not working, if u have no screen?
So if the display of ur MK2 is only using 2 connectors, where is the problem? Just plug it in!
The connector on the top left is normally powering ur (CCFL-)inverter. I'm not sure, about the 1.pin of this connector on the bottom; could be ground (ground is "-" or 0V against the chassis) or it could be the supply voltage for the inverter like it should be on the second pin, where u should found 5V or 10V to 13V. The 3. could be the same (if I count correct or u have to go one back). The 4. (or 3.) pin is the PWM-signal, which will be between 0 to 6V, depending on ur choice of brightness with the keys. I'm unsure about the nxt 2 pins, just check them out. At least the last 2 pins (near 8) are ground (-).
Before u starts to measure anything, it is a good idea to find out, if there is a better connection area for ur test-tips of ur multimeter for a safe work without any harm for the electronic circuit on the board. So u can see, that pin7 and 8 have a connection to the soldering point on the right of them and pin2 should have connection to the fuse F3 S4A ( which means: fuse number 3, quick response, 4A). U can check this, if u had first pull out! the power plug and the battery from ur notebook, while using the multimeter as a continuity checker between the connector pins and the soldering pads around.
If u don't have a clue what I mean, someone should check my spelling or go to the next electronic expert. I'm in London for some days in June (ZZ-Top) or u can send the parts to me. But the best thing is to solve it urself :)

Pls replace only F3, the 4A fuse.
U can check that this will help and that u have no other failures with ur multimeter - set to current measuring above 4A (and hopefully ur multimeter has a internal fuse...). If u put all together (chassis, display...) switch it on and put the multimeter measuring tips on each end of the blown fuse. U should see the light is going on and ur multimeter will show u some numbers with a value less than 4A (maybe 50-100mA). If it is nearly or above 4A, pull the tips quick away, cause u will have a failure in ur led-driver-board.
It could be easier for u, if u first solder 2 thin wires on the blown fuse. So u will get an easy access for ur measuring pins and later u can also soldering a normal fuse on the end of the wires and isolate them with something and fix it on the position behind the connectors. There is enough place for a normal fuse. :)

Just got the CF-52 back today and the backlit screen is now working, So a very big THANK-YOU to all of you posting here that have tried to help me. It was found to be the F3 S4A slow blow fuse which was causing all the problems, the F4 N2A was not there either but no voltage was tracked on either side so this was considered redundant. Glad to finally be able to see the image on screen with backlight working and am very gratefull for those taking the time to answer this post.

Regards to all Billyhl.

Life will beat you into submission.

Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 1 post ] 

All times are UTC-06:00

Who is online

Users browsing this forum: No registered users and 1 guest

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited