HP L1925 Video Input Logic Board won't power on

[EGuevarae]

Re: HP L1925 Video Input Logic Board won't power on

Hello Eduardo



I have a question for you as I am in a quandry, I will explain,
I have 2 boards on the desk in front of me now, both dells, E173fpf + E153fpf.
Both monitors were totaly dead before removing the said boards, they are the 3 in 1 type inverter + psu + video on the 1 board , they are very similar to each other, both have ic like your 1501-50, only these are 1506-50,
when you compare datasheets they are the same to me, my datasheet is



Same pinout + block diagram, the 2 ic of mine have continuity between 3 and 5, I have had no reason to suspect these 2 ICs , no discolouration on the boards,they both look in perfect condition,the 17'' I cannot see anything wrong with it, but the 15'' has burnt out current resistor on it, on the PSU side of it, between the mosfet source and the PWM controller so I believe this is the problem on this board, now to question,

Is it possible that your conclusion was wrong on your IC about it being bad ???

I read all your post and I know your capadility is very good, but I ask because the coincidence of them all being bad on diffrent boards is strange, and if you are right then I have a couple of hard tasks on my hands that I am not looking forward to, so I am hoping that is not so, I wait for your reply,
many thxs
bob

Well, first of all, thanks for thinking I'm capable.
I tested them both and the results were posted here. I'm currently debugging a Delphi system (Time Clock) and I'm busy now, but give me an hour or two, and I'll pull the boards with the chips and recheck them and get back here with the results. Maybe I'm wrong, but I can't think of anything other than this Delphi code someone messed with. Give me some time.
Eduardo

[jpdoe]

Re: HP L1925 Video Input Logic Board won't power on

Thanks, eguevarae

[maverick530]

Re: HP L1925 Video Input Logic Board won't power on

I'm a newbie at all this, but I'm about 90% sure that it was the 1505 IC that was bad. The bad one has no continuity between 3 and 5. Remember the burn on the back of the board? It lines up perfectly with this IC. I have another good IC that does have continuity between 3 and 5 like yours--so I'm thinking it's not your ICs.

I just did a horrible job soldering a good one in.

Best of luck.

[EGuevarae]

Re: HP L1925 Video Input Logic Board won't power on

Hello Eduardo



I have a question for you as I am in a quandry, I will explain,
I have 2 boards on the desk in front of me now, both dells, E173fpf + E153fpf.
Both monitors were totaly dead before removing the said boards, they are the 3 in 1 type inverter + psu + video on the 1 board , they are very similar to each other, both have ic like your 1501-50, only these are 1506-50,
when you compare datasheets they are the same to me, my datasheet is



Same pinout + block diagram, the 2 ic of mine have continuity between 3 and 5, I have had no reason to suspect these 2 ICs , no discolouration on the boards,they both look in perfect condition,the 17'' I cannot see anything wrong with it, but the 15'' has burnt out current resistor on it, on the PSU side of it, between the mosfet source and the PWM controller so I believe this is the problem on this board, now to question,

Is it possible that your conclusion was wrong on your IC about it being bad ???

I read all your post and I know your capadility is very good, but I ask because the coincidence of them all being bad on diffrent boards is strange, and if you are right then I have a couple of hard tasks on my hands that I am not looking forward to, so I am hoping that is not so, I wait for your reply,
many thxs
bob

As promised, pics and notes were pulled out from the Cold Cases Department, and here are the conclusion:

My IC is, as far as I know, BAD , as it should not have continuity between pins 1 (V) and 3 (GND).
How I arrived to that conclusion? Desoldering the 5 pins in both the bad and a good chip (see post #2 for a good example of something you should not do. Kids, don't try this at home ..... this is only for professional IC Killers... ). The pins measured 0.9 ohms between them, both ways. I have pics of before the test, close ups of the bad IC with the pins lifted and even a piece of paper between the pins and the circuit board. Obviously GND (Pin 3) was connected still, as it is the pad too, but the other 4 are/were not. I even had a pic of the reading, and the last pics are of the board as it was stored, still pins lifted. The one that was good and is now destroyed, didn't measure like that. I can't find the readings, maybe because I destroyed it and the readings were not important anymore. I know (well, I think) that there is more damage to the board, and that's the reason it is in the Cold Cases Container, until I get proficient enough to fix it (I have resolved one Cold case : The Proview 568, so this one has still hope ...).
I don't know your particular case, but you can try to just lift (very carefully) the pins and test. Maybe your problem is different.
I hope this helps.
Eduardo


It pays off to take pictures of everything you tear apart after all.... yet, my wife says I picture my stuff more than her .....

[Bobdee]

Re: HP L1925 Video Input Logic Board won't power on

I'm a newbie at all this, but I'm about 90% sure that it was the 1505 IC that was bad. The bad one has no continuity between 3 and 5. Remember the burn on the back of the board? It lines up perfectly with this IC. I have another good IC that does have continuity between 3 and 5 like yours--so I'm thinking it's not your ICs.

I just did a horrible job soldering a good one in.

Best of luck.

sorry maverick
I have missed your post till now,thanks, I hope and think your right, I hope I havent got my wires crossed with Eduardo and this thread, will RE read fully,
many thxs
bob

[Bobdee]

Re: HP L1925 Video Input Logic Board won't power on

Hello Eduardo
thanks for your info, by mavericks last post I think my wires are crossed, will RE read thread fully as it may be that I have misunderstood your conclusions,
thxs bob

[EGuevarae]

Re: HP L1925 Video Input Logic Board won't power on

Hello Eduardo
thanks for your info, by mavericks last post I think my wires are crossed, will RE read thread fully as it may be that I have misunderstood your conclusions,
thxs bob

I've read your posts on DarkStar Dell LCD problem. I think that we will follow the discussion there, as you both have the same LCD and similar problems. Yet, I think that my IC problem is not your problem. It's a shame I don't have a 173 to test/mess with to be of more help to you guys.

[maverick530]

Re: HP L1925 Video Input Logic Board won't power on

Here's some better shots of my board as it stands now:

Notice the dark pits where the arms of the IC used to lay in the board. Is this reparable? If so, how? Should I just fill the pits with solder?

[Bobdee]

Re: HP L1925 Video Input Logic Board won't power on

Hello maverick,
You dont say if the monitor is working in that condition,
with that alteration you made, if its not working as I presume,
then I think you would be better off with it removed, so the guys can see the tracks and make suggestions,
I think myself that it wont be that hard to save,
remove that alteration and post new pictures, if I was you, (thats if it hasnt worked)
bob