fixing a Levono/IBM 6659 PCD monitor (any idea what part 'F701' might be?)

Fuse, 4AT is 4Amp Time delay. But fuses dont olfact when they go, so it sounds like something else is wrong. Freecycle might be quicker.

NT

Thanks, the fuse was indeed blown. However, after replacing it, I'm back to where I started with this odd behavior of powering up only half the time. This occurs even when the monitor has been sitting undisturbed, so I don't think its a loose connection. In fact, it almost seems as though the problem only occurs after the monitor has been plugged in for a while (maybe 30 mins), but this might be coincidental.

I'm pretty sure the problem is somewhere on the '48.L2501.A04' board; not very specific I know. Is anyone familiar with this or similar monitors? Any ideas as to what parts I should look at replacing? Any idea where a schematic could be found?

thanks aga> snipped-for-privacy@gmail.com wrote:

Are you far from civilisation? If not, why spend time on it?

NT

1) First, the 6659 is a pretty fancy display (21" and will do

2) I'm a graduate student and don't have money to buy a new display or pay for this one to be repaired.

Right I see. Well, repairing smpsus driving EHT stages is not especially straightforward, so if youre a graduate student I dont think your odds are very high on this.

However if you must, the smpsu is refusing to start: why? Either its at fault or its going into protection mode because of a fault downline, which usually means a horizontal output area fault.

NT

Just out of curiosity, are there typically EHT stages in LCD monitors? Maybe for the backlight?

A bit more info on the symptoms which might serve as a clue: For about

thanks, Graham

no, i was thinking it was crt for some reason.

CCFLs do run on HT

if its lcd its more likely to just be the psu.

NT

Sorry, if did not see your second reply when i first reply. You said on the second reply, that it needs a restart after 15 min. I see a whole bunch benq 's lcd has the same problem, sometimes it is the transistor, or capacitor, transformer, or even cold solder joint.

If you have an ESR meter, you can check the capacitor(disacharge the big cap before mesauring it) Colder solder joint is easy to find, just need to look carefully. Transformer(inverter) is liitle bit difficult, Since it is difficult to find the replacement

First i will look at the board, and see any discoloration(if something run hot for a long time, it will change the color of the board.) If somthing run very hot, it usually break first. Then Measure the cap with esr meter,check colder joint, then measure the voltage of different rail, and find out which section cause the problem.

Usually the manfacturers don't give out any service manual, but if you want to learn how lcd power supply works, you can goolge "hp vf17 manual". This is a service manual for HPvf17, it has the block diagram and flow chart. It teachs you a lot so read it carefully and try to understand it as much as possible.

i guess your lcd may has bad caps or colder solder joint, since you can't power it up 50%of the time and it needs a restart will made the lcd alive again.

snipped-for-privacy@gmail.com wrote: