Backlight replacement troubleshooting help needed

[wisgro]

Recently replaced the backlight in my T23. All cables are connected but lcd panel is black, not even a ghost as if it isn't getting power. Before replacement I had the classic symptoms: reddish tint progressed to flickering then all I saw was a faint ghost. I plugged an external monitor in. Works fine. Any advice or links to troubleshooting the backlight greatly appreciated. I have had this thing apart 3 times now triple checking all lcd cable connecitons, etc but can't find the problem.
Thanks, Walt

[rkawakami]

Welcome to thinkpads.com!

If you do not see any pixel activity (ghost image) on the display when you are getting a signal out of the external VGA port try cycling through the internal/external monitor settings by hitting Fn+F7 a couple of times. This will activate the LCD and external monitors in the following sequence:

- LCD only
- External only
- Both

If, after pressing this key sequence at least three times, you do not see any pixel activity on the LCD, but the external monitor does work properly, then the problem could be on the motherboard, the cable or the panel.

Troubleshooting:

If LCD's backlight does not turn on at all AND no pixel activity is present after using Fn+F7 at least three times:

- ribbon cable and/or wires to CCFL damaged/unplugged
- lid closure switch stuck
- motherboard issue

If LCD backlight does turn on yet there's nothing on the screen:

- ribbon cable damaged/unplugged
- LCD panel is damaged
- motherboard issue

If LCD backlight does NOT turn on and there's a ghost image on the screen:

- inverter board damaged/unplugged
- wires to CCFL damaged
- bad CCFL

[wisgro]

Thanks for responding so quickly Ray. I tried the fn + f7 sequence you suggested. Once turns the external monitor off, second time turns it back on. The lcd is still blank. I pressed the The lid closure switch shuts the external monitor off. I've pressed that many time both with power on and off.
I'm at a loss. Checked, re-checked and checked the cables and all looks fine. The ribbon cable connector is plugged tightly into the mobo and is held in place with a screw. Cables don't appear to have any damage.
The part that puzzles me is that a ghost image displayed when the old ccf died. The next problem developed after I installed the replacement back light. Every description I found of the problem says that a ghost is visible when the back light dies. U figured if the replacement is no good I should still see a ghost.
I printed the pic of a ribbon cable for sale. The description said T23 but the cable pic doesn't look like mine. The pic shows 5 points of connection. Mine only has 2 that I can see... 1 at the upper rear of the panel and one to the mobo.
Walt

[rkawakami]

The ghost image on the LCD means that the video signals were getting to the panel but the backlight was not turning on. Since you have appeared to have disassembled the LCD panel to replace the backlight, the only thing I can think of is that the panel was not re-assembled correctly and/or some damage was done to affect the display. Said damage could be in the panel, the cable or the motherboard.

The ribbon cable for the T23s should have 5 "ends":

- motherboard connector; large white connector, secured by a bracket
- inverter connector; white connector about 1/2" long
- LCD panel connector; thin about 30 gold 'fingers'
- UltraPort connector; at top end of ribbon cable, 13 'fingers' separated into two groups
- ThinkLight LED; 1/2" wide with a small white 'block' on it

Here's a picture:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0102644139

[tfflivemb2]

As much of a pain as it would be, I would check your soldering connections on the CCFL (backlight).

[Msmax]

Just make sure the connector of the LCD cable which connects to the inverter board is in place. If you say your cable has only 2 'ends', then probably this connector is not fitted to the inverter board.

Msmax

[wisgro]

Thanks everyone. Your tips are very helpful. The link to the picture is the same one I looked at the other day/printed. Guess I'll have to disassemble the panel one more time to check the ribbon connections. After viewing the responses I drew a blank trying to picture the ribbon cable connection to the inverter. That could be the problem.
Walt