J720 Problem

everyone, I have a second hand J720 and it has something wrong
when i press the power key, it switch off the screen but switch on again
It cant go into standby mode
Also, the touch isnt working
I cant dag the icons on desktop and when I start a program,
it open and close automaticlly
does anyone wt's going on?
Can I fix it myself?

Sounds like something happened to the display cable. I've got a M900 which also had this kind of problem before. I needed to press the power button a few times to turn it off. Then I opened the case, disconnected the cable and then gave it a firm connection. That did solve the problem for me.

Good to see another Jornada user from Hong Kong! Hello there!

Another J728 user from HK.

I've got this 3 months ago, but I just shook it a little bit and all got back working.

In the past I have used a non-destructive "slapping" of the J and problems went away.

There is a good video about disassembling the jornada here in HPCFactor. I solved many problems on my old jornada after I learned how to open it. Usually 99% of the problems that the jornada presents are cable problems (dirty cables or bad connected). You just need to connect them better and you have a new jornada.

My experience is pressing Power using a quick and short press. A slow and long press could lead to off and on again. Of course, hardware problem needs attention inside.

My 900 is naughtier. Short and quick press makes no difference unless I reconnect the cable.
Could it be an issue of aging cable, or just some factory fault?

I took a video about the problems:
http://www.youtube.com/watch?v=8yyC61Np4cY
Does anyone know how to fix it?

Have you tried using a stylus to see how the screen issues compare to using just your finger to "tap"?

Edited by Hal 2010-03-23 12:24 PM

I've tried it with stylus
Just the same, no different

Looks like (for whatever reason) it thinks that there is a stuck key.

Check the keyboard diagnostics if you can and re-connect the leads as above.

You could even try disconnecting the KB and reboot, calibrating,and trying the screen to see if it makes a difference.

I think it is not the problem of Kb
It'll never have strange sound when i type the "Start" key on the KB

The least destructive disassembly to check connections is to take the screen apart. But it invariably ruins the "HP" and "720" labels. I have been able to remove them with minimal damage and in SOME cases iron them flat again and reglue (I prefer to use the thin double-back tape like for photo albums). Or you can pierce the labels to get to the #6 torx screws in both places. Then you can pry open the screen cover from the bezel and expose the back of the screen and the 2 ribbon cable connections. With the top off, you can support the screen in place using a rubber band and then boot up and see if anything changes after you have unseated/reseated the ribbon. Try at your own risk!!

To get to the other end of the cable requires disassembly of the main-body case, which is shown in the file video on this site. Of course could be the cable itself and not its connection that is the problem. You wouldn't know without swapping parts with known working ones. You might be able to find a distressed 720 on ebay and get one good one out of 2, but there are risks.

Edited by Hal 2010-03-28 3:37 PM

Could it be a problem with the keyboard cable/connector?