7970 backlight broken (i think)

Answered Question
Jun 15th, 2007

Hello again,


So I'm pretty sure I have it nailed down to the backlight on the screen is broken. I have tried it via PoE and CP-PWR-CUBE3 and it still powers up and I am able to see what is on the screen if I tip it at just the right angle. But otherwise the backlight is non-functional. I have also confirmed (by tiping the phone to just the right angle to see) that the brightness bar for the phone (when power cube is used) is all the way up.


What I'm curious about is.. what do I do now? I got the item used and I'm not sure I could get a refund. Basically I'm begging for the possibility of information to change the backlight. I hear on many lcd screens they are able to be somewhat easily changed so a whole new unit doesn't have to be purchased.


Thanks a bunch!


edit: or maybe just some more ideas on what to try. seems strange that the backlight just craps out.. I've never before heard of such a problem with the 7970 or an LCD (such as monitor or tv)

Correct Answer by Paolo Bevilacqua about 9 years 8 months ago

Correct, with the reset sequence, you cannot hardset TFTP, because the phone will use DHCP exclusively.

The phone will do all by itself once DHCP reply with option 150 is provided. TFTP32 has a nice log window that allows you to monitor both DHCP and TFTP progress.

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Paolo Bevilacqua Fri, 06/15/2007 - 14:51

LCDs can and do go bad. Specifically, the backlight lamp blows.

Now, is the rightmost button of the five in a line horizonal below the display, lit in green ?

If so, press it. If no result, the backlight lamp is gone.

donjohnson911 Fri, 06/15/2007 - 14:59

It is not lit in green.


Do you know if its possible to have it fixed or do you know how to fix it for a somewhat reasonable price?


I started a factory reset process just as an idea but I seem to be having problems with that now too. Each line key flashes, in sequence over and over, sometimes the headset key will light and stay light while the line keys flash, and some times one of the line keys will hold and stay lit with the headset key. This also happens with the speaker key.


But it has been doing this for about 10 minutes now and just keeps doing it over and over. I have term70.default.loads on my TFTP server but it isn't a cisco TFTP server, and I havent noticed any way to change which IP it looks for this file on.


Any comments on this?

Paolo Bevilacqua Fri, 06/15/2007 - 16:18

Well, it depends on how much you are determined about fixing it. Try emailing [email protected] about a spare backlight lamp. They can ask you to remove it to measure it, but if they can't help you, I wouldn't know who to ask. Cisco doesn't sell phones spares parts.


About the reset sequence, what it does, it resets the phone to get an address via DHCP. The DHCP server must also provide TFTP address via option 150.


If you use tftp32 (free for XP), you can do dhcp w/option 150 and tftp server with a single program.


donjohnson911 Fri, 06/15/2007 - 16:51

So I don't need to hardset a TFTP server on the phone? I'll download this tftp32 for my workstation and put the files on it. The phone will just locate it and get the firmware by itself?

Correct Answer
Paolo Bevilacqua Fri, 06/15/2007 - 17:26

Correct, with the reset sequence, you cannot hardset TFTP, because the phone will use DHCP exclusively.

The phone will do all by itself once DHCP reply with option 150 is provided. TFTP32 has a nice log window that allows you to monitor both DHCP and TFTP progress.

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