Take a look at our
ThinkPads.com HOME PAGE
For those who might want to contribute to the blog, start here: Editors Alley Topic
Then contact Bill with a Private Message

Several backlight DEAD!

Older ThinkPads from the 300, 500, 600, 700 Series, iSeries, Transnote etc.
Post Reply
Message
Author
el_Capo
Posts: 18
Joined: Sun May 26, 2024 11:14 pm
Location: Santiago, Chile

Several backlight DEAD!

#1 Post by el_Capo » Sat Jul 06, 2024 6:05 pm

I have a problem with 3 of the older computers in my collection (T21, T22 and 700X) which have their backlight burned out.... (when I illuminate them with the phone's flash you can see what the screen shows). In some cases they momentarily return to normal but only briefly. :( I was investigating and found a video on YouTube of an Indian who unsoldered a chip near the monitor connector into the motherboard, solving the problem....
as always any ideas or recommendations are appreciated...
Regards!
Enthusiast Thinkpads Collector... 8)
770X-X220(x2)-X270-X390
T21-T22-T42-T43-T60-T61
R51 :lol:

panips
Posts: 32
Joined: Mon Mar 25, 2024 10:28 pm
Location: Saratoga, CA

Re: Several backlight DEAD!

#2 Post by panips » Sun Jul 07, 2024 1:59 am

Please make sure whether the CCFL is dead or it's the inverter board issue.
A simple solution (for me) is to get new LEDs (from AliExpress) and do some soldering works. Usually the led comes with 4 wires where

ren/voc: should be > 9V, I did not find any manual nor specs but I believe 9~20v is OK
yellow/enable: > 3.5v(?)
white/adjust: it depends but it CANNOT be floating (which is different than what I saw on some Japanese twitters or the LED keeps flashing, I can confirm that)
black/ground: hmm...

you can either reuse the inverter board or solder them to the mother board.
:lol: 230Cs, 235, 240, 330Cs, 360CSE, 365XD, 370C, 390, 535, 550BJ, 560, 570, 600, 750C, 755CX/CD, 760LD/E/XL, 770Z, PC110, R30, S30, TransNote...
:( PS/55 Note, 220, 315ED, 360PE, 365CD, 500, 535E, 701C/Cs, A20p...
WTB: 700C, 7xxT, 755CV/CDV, R50p w/QXGA (and other ThinkPads before 1995)

SMA
Junior Member
Junior Member
Posts: 337
Joined: Fri Jun 29, 2007 3:48 pm
Location: Copenhagen, Denmark

Re: Several backlight DEAD!

#3 Post by SMA » Sun Jul 07, 2024 8:08 am

For the T21 the most likely cause is a broken LCD cable.
Read about it in this topic

viewtopic.php?t=45602

Might be the same for the T22.

el_Capo
Posts: 18
Joined: Sun May 26, 2024 11:14 pm
Location: Santiago, Chile

Re: Several backlight DEAD!

#4 Post by el_Capo » Sun Jul 07, 2024 3:09 pm

panips wrote:
Sun Jul 07, 2024 1:59 am
Please make sure whether the CCFL is dead or it's the inverter board issue.
how i check this?? could you gave me some details?
A simple solution (for me) is to get new LEDs (from AliExpress) and do some soldering works. Usually the led comes with 4 wires where
ren/voc: should be > 9V, I did not find any manual nor specs but I believe 9~20v is OK
yellow/enable: > 3.5v(?)
white/adjust: it depends but it CANNOT be floating (which is different than what I saw on some Japanese twitters or the LED keeps flashing, I can confirm that)
black/ground: hmm...
do you have links??

Thanks for responses!!!
Enthusiast Thinkpads Collector... 8)
770X-X220(x2)-X270-X390
T21-T22-T42-T43-T60-T61
R51 :lol:

panips
Posts: 32
Joined: Mon Mar 25, 2024 10:28 pm
Location: Saratoga, CA

Re: Several backlight DEAD!

#5 Post by panips » Mon Jul 08, 2024 11:46 am

Replace with known-working inverter board or ccfl and see if it works. Or, you may also check the outputting voltage of inverter board. If the inverter board does not work, you can also test the fuse. Sometimes it's just because of a blown fuse.

I don't know what e-commercial site you'd like to use but google with keywords "Backlight Strip Kit LED" might be helpful.

update:
might be the protection circuit of the inverter board if it blacked out after a while
might be bad capacitor if sometimes it works but sometimes it does not.
:lol: 230Cs, 235, 240, 330Cs, 360CSE, 365XD, 370C, 390, 535, 550BJ, 560, 570, 600, 750C, 755CX/CD, 760LD/E/XL, 770Z, PC110, R30, S30, TransNote...
:( PS/55 Note, 220, 315ED, 360PE, 365CD, 500, 535E, 701C/Cs, A20p...
WTB: 700C, 7xxT, 755CV/CDV, R50p w/QXGA (and other ThinkPads before 1995)

el_Capo
Posts: 18
Joined: Sun May 26, 2024 11:14 pm
Location: Santiago, Chile

Re: Several backlight DEAD!

#6 Post by el_Capo » Fri Jul 12, 2024 6:41 pm

i found this one in aliexpress---- :roll:
could you tell me if will works in my T21/T22?? :?
https://i.ibb.co/MnZRfCH/Screenshot-202 ... 193624.png



https://www.aliexpress.com/item/1005007 ... ry_from%3A
Enthusiast Thinkpads Collector... 8)
770X-X220(x2)-X270-X390
T21-T22-T42-T43-T60-T61
R51 :lol:

RealBlackStuff
Admin Emeritus
Admin Emeritus
Posts: 23930
Joined: Mon Sep 18, 2006 5:17 am
Location: Loch Garman, Éire

Re: Several backlight DEAD!

#7 Post by RealBlackStuff » Sat Jul 13, 2024 12:46 am

Those provide ONLY backlight, but NO picture.

T20/T21/T22 inverter FRU 10L1402 or 91P7741:
https://www.elecok.com/ibm-lenovo-think ... l1402.html
https://www.pchub.com/hitachi-invc571b- ... 1402-p6747
Lovely day for a Guinness! (The Real Black Stuff)
But I actually prefer Murphy's from Cork!

el_Capo
Posts: 18
Joined: Sun May 26, 2024 11:14 pm
Location: Santiago, Chile

Re: Several backlight DEAD!

#8 Post by el_Capo » Tue Jul 16, 2024 6:41 pm

RealBlackStuff wrote:
Sat Jul 13, 2024 12:46 am
Those provide ONLY backlight, but NO picture.
If you notice, in my original post I explained that you can see data on the screen, that is, it provides information whenever you illuminate the screen with an external source (flash phone) from close by!
Greetings!
ps. I ordered a couple of LED strip bands from Aliexpress as well as the CCFL module
Enthusiast Thinkpads Collector... 8)
770X-X220(x2)-X270-X390
T21-T22-T42-T43-T60-T61
R51 :lol:

RealBlackStuff
Admin Emeritus
Admin Emeritus
Posts: 23930
Joined: Mon Sep 18, 2006 5:17 am
Location: Loch Garman, Éire

Re: Several backlight DEAD!

#9 Post by RealBlackStuff » Tue Jul 16, 2024 11:09 pm

Just in case: where would you put those "LED strip bands"?
Lovely day for a Guinness! (The Real Black Stuff)
But I actually prefer Murphy's from Cork!

Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “ThinkPad Legacy Hardware”

Who is online

Users browsing this forum: No registered users and 7 guests