Intermittent failure of HP1740 monitor

[cascara]

I have an HP1740 monitor which although it is new has an intermittent display failure problem. The monitor was bought 4-5 years ago together with two other HP1740's. The problem display was given a quick test at the time of purchase then returned to its box. Total hours shown was 107.

The problem display was taken into use about six weeks ago when a display failed completely.

The problem display ran for about 26 minutes then the brightness reduced followed after some 5 secs. by a complete blackness. The display LED remained lit. After some 5 mins switching the display off and on gets the display working again but the switchoff often recurs after an uncertain amount of time.

After the obvious wiring checks I moved the display to my other computer (different video card and connecting leads). There was no difference but after a couple of days the display did not fail. The display carried on without any problem for about two weeks.

After a no-problem two weeks I had two days when it went back to the 26-30 mins then failure. This 'good fortnight bad two days' has just repeated itself.

I took the discarded display apart so know that it is not easy to try a cure put the display back together to see the effect if any. So I am hoping that someone will recognise the symptoms and point me in the right direction.

I have been unable to think what could cause this bad then good behaviour.

[selldoor]

Re: Intermittent failure of HP1740 monitor

Welcome to the forum-
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

It will be useful if you can say a bit about yourself - skills tools etc.

[budm]

Re: Intermittent failure of HP1740 monitor

Does it look like this?
http://s807.photobucket.com/albums/y...HP/HP%20L1740/
Look for bad solder joints, this is made by BenQ.

[jetadm123]

Re: Intermittent failure of HP1740 monitor

Try using a hair dryer to accelerate the failure time. This should help you pinpoint the area of the failure.

[George Ortiz]

Re: Intermittent failure of HP1740 monitor

Pictures would definitely help here. I am very familiar the L1740 series. There at least
four different power supplies/logic board/display combos for this series. Two of the series even after repairing the power supplies turned out to be bad ccfls. One of the series was definitely blown capacitors. The final series BenQ I am not familiar with, because we don't have them, but posting pix here definitely helps.

[cascara]

Re: Intermittent failure of HP1740 monitor

Thank you all for your thoughts.

I am 'merely' a hobbyist so what surprises me is that a bad solder joint can show itself in a random fashion. Your experience says that even though the display is used in a more or less consistent way and the ambient temperatures are virtually the same the bad joint will sometimes show itself and sometimes not.

Taking that on board I think my best plan is to wait until the next failure when I shall disembowel the display and if the use of a hairdrier does not point me to the problem I shall look at the joints. If that also does not reveal any thing I shall try to upload some decent photos.

Thanks again for your help.

[cascara]

Re: Intermittent failure of HP1740 monitor

I read this thread last night -

https://www.badcaps.net/forum/showth...T4+%28FP71G%29

The symptoms seen by retiredcaps are very similar to those shown by my monitor.

The thread was from 2010 but stops before any cause of the shutdowns was identified.

If retiredcaps reads this I would appreciate hearing if he can recall any cause being found.