cf-29 Mk4 LCD backlight does not work now - Please help me

hi bros.

my Mk4 just shows me new issue.

I worked last time fine, then left it at home.

3h later, I come back home and start installing the microphone following this thread ( http://forum.notebookreview.com/panasonic/240268-intern-microfon-cf29.html) because I just had 3 pins connector for that installation.

after plug in the microphone, I start the laptop and see that the backlight of the LCD does not work. It is really dark and very hard to see what is happening there.

I try to plug in and out the LCD cable, no luck.

I unplug the microphone, and try again with LCD cable, still no luck. The screen now still show me that the laptop is working, I can see it runs but very very dark. Of course, when I attach to external LCD, the laptop works just fine itself.

One more thing is that, I can hear the wind sound from the microphone, or when I touch my finger to my microphone, I can hear that sound. But when I speak, even if speak loud close to the microphone, I don't hear anything. (I use 2nd laptop to test this function through Skype). I even use 2 microphone from my Nokia phone, both of them show the same behavior like that.

Could you tell me how to fix this issue? Thank you very much.

 

U have to drill a hole in the plastic, where the mic is situated. Otherwise u will only hear the bodynoise
Pull the white connector http://forum.notebookreview.com/att...018255-changing-ccfl-led-display-p4100027.jpg on the left of the bottom of the mic-connector out and after that, push him back in the socket. (this connector is for ur touchscreen and the ccfl-power)

 

when I tested the mic, i put it outside of the laptop with a long wire, that's why i can touch it with my finger. Because I want to make sure it works before plug it into the laptop in its small position. However, the issue was that.

Do you have any idea?

i do the same way, but nothing changes.Issue still there. Do you have any idea?

thank you

 

Check the cable connector maybe one or two wires are pulled from the connector base otherwise you have a motherboard to be repair by someone who are familiar with this unit on a backlighting circuit. Get the schematic and you will see what I am talking about.

For mic., it must be line 1 and 3 on the connector.

ohlip

 

i double check those, but no luck.

i also read this thread that you also did mention something there: http://forum.notebookreview.com/tou...um/392298-wtb-cf-29-backlight-inverter-2.html

i have a Mk5 now also in working fine condition, should I swap them together to make a test? I am worrying that it may destroy both of them. I really hate that.

yes, my 3 pins connector just has 2 pin lines which are at 1 and 3 only. I read the thread of microphone installation before doing the job.

but it is strange that i can not hear the voice, only the wind sound if I whist or the sound if I touch that microphone, other than that, no human voice.

 

Try to hook it up on the external monitor or you may hook up the LCD of the other unit. it doesn't nececssary swap it all completely. Just take out the defective one. Place the other toughbook beside of it or side by side with the LCD harness ready and then hook it up directly to the unit that you are going to test. You know what I mean less work just to confirm if the mbo. still 100% working.

BTW, I guessed you worked on the unit with battery inplace.

ohlip

 

-...maybe u have to try a different type of a microphone.

-Are u firm with a voltmeter? If no, don't read further. If yes, u should check the voltage on the white connector CN9. If there is no voltage on the right side of the pins, the fuse on the mainboard is broken. Also u can check the fuses first: just make ur tb powerless, detach the accu and now u can check the fuses on the bottom of CN9 with an multimeter. They should have zero ohm.

 

thank you very much. I think I should change the microphone to another type (update: I take apart my Microsoft VX-3000 webcam, then cut down the microphone from that one. Now the microphone works just fine. Thanks a lot for your tip).

- I checked the CN9 from left right with 11 pins:
1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11

Pins number 1,3,5,6,7,8 no voltage.
Pins number 10, 11 have same about 40 voltage
Pins number 9 is 1V, 4 is 12V, and 2 is 8V.

- both fuses (i see there are 2 of them, is that right?) response with under zero Ohm.

i have no idea what next i should do now.

please give your advice. thank you

 

sounds good so far.

pin 9 should be more. But depends on ur multimeter, because there is the pwm-signal... Had u used the tb-chassis as ground and had u adjusted the brightness to max level?

The next step is to open the display and check the voltages which u found on pin 7 to 11 on CN9 u have to find the same on the inverterboard on the back of the panel.

 

thanks for your idea. However, do I need to do that with my inverter? because I also put whole this LCD screen into my Mk5 and it works just fine.

update: i also just measure both fuses at bottom under CN9, they both have 12.5V. Is this normal?

 

update: i just found one non-working fuse, this is the fuse under the bottom right under the LCD cable which is the long pins beside CN9.
its name is : J3E 59 (it is really tough to see the name, i have to use my Nikon D700 + macro lens 105mm f/2.8 in order to see that name. LOL).

this fuse shows no Voltage when the laptop is on and shows near 1K Ohm when the laptop is off.

Except this fuse, all the other fuses are in working condition.

I don't know how to find out a replacement for this fuse. If you have any idea, please give me your advice.

 

Fuses should start with an 'F' , i.e. F4, F5 ....

I have an electronic store here, where I can buy nearly any part and component.

But back to ur really problem: could u pls verify the voltages on ur display inverter in ur MK4? Here is a pic and where to find which voltage: http://forum.notebookreview.com/panasonic/471036-changing-ccfl-led-display.html#post6067251. Please, don't cut ur wires ;-)

 

Quote:
Originally Posted by neverlostdata
hi bro,

i use that LCD from my Mk4 with my Mk5, it works well.

so I am not sure why you want me to check the inverter on LCD Mk4 again? do you think it is the issue from mobo? please tell me. thank you

VUONG
U found the voltages on the fuses and on the connector on the mobo, but sometimes u had bend an pin inside of an connector or an cable is a little bit loose or whatever... it's for verifying the signals.
Hope u had not killed the PWM-signal on pin 9. This signal can u check with an multimeter with the posibility to check frequencies or better with an oscilloscope.

And please copy this mail to the thread in the forum, so anybody can get an advantage from this issue

------------

I copy here my PM with Onirakkis. This hope will be useful for someone.

My issue still be there. idea are welcome. Thank you

 

I'm not sure if chasing voltages is what you need to be doing. As I recall somewhere... The battery was installed when you were working on it. When this was done in the old CF-28 days.. This pretty much guaranteed a blown backlight fuse. I would be checking the fuses for continuity! A good fuse will shown continuity and a bad one will not. The ones on the CF-28 were a 63V 1A type and were small white SMD fuses. On a few, when I couldn't harvest off of another mobo, I would just use a small 1A Buss type fuse and shrink wrap it. There was plenty of room to tuck it in there. Plus... Trying to check for voltages can lead to shorting pins and creating even more issues if you aren't careful. I check for continuity first...

Just my .02