HannStar Monitor

[rigeback]

Found this monitor today at the dump and tried it out, monitor comes on with a line on the screen and then remains white, lamps are working and power supply. Took it apart hoping to find a SMD fuse blown (like before!) but no such luck, this ones a better model I guess since it has digital out put.
I would like to get it going for keeps as its in fair shape if you guys have any ideas. The photos are not so clear in some cases please let me know if I should re-shoot some areas.
Many thanks

[rigeback]

Re: HannStar Monitor

Found this monitor today at the dump and tried it out, monitor comes on with a line on the screen and then remains white, lamps are working and power supply. Took it apart hoping to find a SMD fuse blown (like before!) but no such luck, this ones a better model I guess since it has digital out put.
I would like to get it going for keeps as its in fair shape if you guys have any ideas. The photos are not so clear in some cases please let me know if I should re-shoot some areas.
Many thanks

hope I get some feedback!

[alexanna]

Re: HannStar Monitor

What type of line? Like a colored row of stuck pixels?
What brand are the Blue/Green caps?
Dose the power switch and PLED respond normally?
Have you verified any voltages?

[rigeback]

Re: HannStar Monitor

Theres 2 slight marks about 2" long (that I could live with) as I don't think the pixels are stuck but on the other hand they could be.
I dissasembled the screen and gently cleaned the area with isopropyl and the mark seem to dimish slightly.
Its basic assembled and hooked up to the computer again with no color what so ever just nice and white.
The power switch responds normally although no voltages have been measured, the green and black caps look okay.
I think the problem is on the lcd board simular to previous senario.

[rigeback]

Re: HannStar Monitor

Whoops, durring start up the screen does show pixel lines darker where the mark is located, the other controls do not change anything except for power switch.

[alexanna]

Re: HannStar Monitor

Well low and or no voltage going to the panel could mimic an open fuse.
Just because the caps look OK doesn’t always mean they are good.
There are some capacitors that are considered replace on sight.

[rigeback]

Re: HannStar Monitor

The black caps on the video board are Capxon and the green caps on the power board seem to be GFCMD or GF(M).

[alexanna]

Re: HannStar Monitor

See what some of the other members say, but I think the Samxon GF or on the list.

[rigeback]

Re: HannStar Monitor

okay thanks

[killian6pk]

Re: HannStar Monitor

I'm still to new at this to give much information, but two things I would check. First I read somewhere that single lines going from top to bottom were connection problems in the tape carrier package which I think is shown in your picture number 5. If that is true I can tell you what I read about the solution to that problem. Also in the power supply why are the pink and white wires glued into the board like that. It makes me think someone broke off the CCFL connectors and this was a patch job. You might check that out on the bottom of the board and see if that is what has happened. I would think that might be a source of your problems also.

[Koda]

Re: HannStar Monitor

You should also check for cold solder joints, there are some LG TV's having vertical lines due to cold solder joints. Maybe your's is a problem similar to those.

[rigeback]

Re: HannStar Monitor

Yep you're right it seems someone has been here before, I too wondered why the CCFL connections were not the same, however on the back there is other component replacement that are soldered in an odd way, will put some pictures on shortly.
As for the carrier tape N-5 it seems okay, N-7 is the line that has a slight problem durring start up, I would be interested in hearing what you read about the tape carrier though.
Thanks

[rigeback]

Re: HannStar Monitor

Here is a pic of the bottom side of the power board and one can see that
Q104 and Q105 are modified parts without the middle leg not being soldered, problem will be understand what replacement is required!
The current parts are numbered with 9977GH 50542

[killian6pk]

Re: HannStar Monitor

What I read said to identify the area of the screen in relation to the TCP and to take the aluminum cover off the TCP and take a thin small 3/4" square (my guess) piece of foam rubber maybe 1/4 to 1/2" thick and put over the area on top of the TCP then replace the aluminum cover and tighten the screws as tight as you can without stripping them. This was supposed to put some pressure on the weak connection which was what the person said was causing the problem in the first place. He also commented that the TCP was very fragile and could not be repaired by regular means so be carefull.

On the other parts, if you are talking about the two black bodied parts sort of in the middle of the board those are transistors it looks like and they are only supposed to have two legs soldered along with the large joint on the top. If you want to test them take your Digital Multi Meter on the Ohms setting and check the following: Orient the long solder joint to the top and the lower left leg is the Gate the right leg is the Source and the Top area is the Drain. Using your DMM probes check between S-G, S-D and G-D and record all of your reading for both transistors. Someone better than I should be able to interpret your reading as to whether these are good or bad transistors. Try to google the part numbers to find a Data Sheet on them so you can check on spare parts and have info at hand.

[rigeback]

Re: HannStar Monitor

Did some measuring and I only get a reading between G-D 133.6 @ 200 S-D & S-G rest 1

[alexanna]

Re: HannStar Monitor

I am having a hard time seeing how on a loose flex ribbon from the T-con to the panel is causing a white screen; I have noticed what I will describe as thin colored racing stripes through the picture when ONE flex cable has loosened. If there is the problem with the bonding you will have to replace the panel.
The pink and white wires soldered to the board are probably factory; they just needed to extend the connection to the CCFLs on that half of the panel. To verify the transistors are installed correctly, check to see if the solder pad that the center tab is soldered to shows continuity to the pad where you think the middle leg would be soldered to.
From what you describe you have a predominately white screen? Is that correct?
Dose the flex ribbon cable from the signal card to the panel look damaged in any way?
Is the voltage going to the signal card good?
Dose the panel have voltage going to it?
And do you notice any common voltages on the signal card [5v-3.3v-2.5v or 1.8 volts]?

[rigeback]

Re: HannStar Monitor

Yes the transistor centre pad shows contenuity to the place where it should have been soldered.
Yes the screen is completly white when powered on although it receives the suspend and wakeup from the video card ok, I just check all the flex ribbon at the board terminals for contenuity and they are okay, the ribbon was slightly crushed.
Will have to reassembble to check the voltages!

[rigeback]

Re: HannStar Monitor

According to the data sheet for this trasistor the Gate source should -+25 Volts and the drain source 60 Volts http://www.datasheetarchive.com/AP99...datasheet.html

[rigeback]

Re: HannStar Monitor

Okay did a powered on test of the transistors and on both I get 12.1 Volts between the D-G & D-S

[PlainBill]

Re: HannStar Monitor

According to the data sheet for this trasistor the Gate source should -+25 Volts and the drain source 60 Volts http://www.datasheetarchive.com/AP99...datasheet.html

Those are the MAXIMUM voltages. If you have a 12V source and are switching a non-inductive load, you would want a transistor rated for at last 12V; 25V would be better. If there is an inductive component, a higher voltage would be much better.

Something similar applies to capacitors - you want a significant overvoltage for a filter capacitor. 25 volts for a 12 volt supply would be typical.

PlainBill