Hannspree HF257 2-3 seconds black

[Hippie459MN]

I have a Hannspree HF257 (25") and about a month ago had the bottom left side of the screen start doing a weird flickering and turning the monitor off and on seemed to fix it only to to it again the next day an turning it off and back on fixed it again. A few days later after not having any issues at all the screen just went black all together and turning it off then back on it would light up for about 2-5 seconds then black again so I brought it to a friends that said he would test some items and said he had an ESR tester for the caps. Later that day he said that I had some bad caps and a bad mosfet and had found a complete replacement board on ebay so I ordered it and when I put it in, it worked worse then the one I took out. The replacement one now would come on for 2 seconds and go out and this one has a very faint click and then an audible hum as soon as the CCFL tubes go out but turning off and back on it is quiet until the back light goes out again then the humming again. Turning the brightness down saw no changes.

So at this point I decided to put the original board back in and try turning the brightness down on the monitor and was able to get it to stay on as long as the brightness was below 23. About 25 it would go out again, 24 it would stay on for a good time and then go out, 23 it was on for a few hours before I turned it off.

Well, Now I have told this friend I am just going to replace all the caps and go from there and now he is saying they all tested good (None of them are puffed up or broke open that I can see) so I am not 100% sure now so going to do that in the next day or so.

Now I have been trying to find a replacement inverter transformer in hopes that that might be the issue but have had zero luck finding anything with the same part number and then in this post (https://www.badcaps.net/forum/showpo...24&postcount=1) I do notice them saying that the TDK XAD819AR has the same inverter and have found someone online with a few of them but I can not confirm that yet. I am waiting for them to get back to me. But I was wondering, what would be the best way to test this inverter and would anyone know of replacement that would work?

Also, I was leaning towards a CCFL tube being the culprit possibly but not sure of a really good way to test as I dont have another monitor or spare tubes to use to test with. Also, How much of a job is it to replace a tube if that is the case? I have never personally done one and my friend is saying its not worth it and way to big of a job but to me from what I have been looking at on youtube and stuff it doesnt really seem like it would be to tough. Anything to really watch out for when changing them?

Thanks for any help and here are some pictures. The first one is the inverter transformer with the part number, the next 2 are some pictures of the identical board that I had that are nice and clear. and the last picture is my actual board. Mine is missing the white silicone on the back side like the other photo. Looks to never have been on there at all. It is the best picture I could get with the camera I have.

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

I put the original board back in today to try something and I was able to keep the screen lit up with the brightness down to 20 but as soon as I removed any number of the CCFL connectors from the board, 2 seconds and black. even with the brightness down to about 10. I didnt go any lower then that. I plug all 4 plugs back in and it stays lit up again so long as I dont bring the brightness up to much. So where to go from there? Could this rule out a CCFL tube? I am not going to let this monitor get the best of me just yet.

[selldoor]

Re: Hannspree HF257 2-3 seconds black

Test the Inverter transformers by checking the secondary wiring resistance.
POWER OFF, meter on ohms 2000 test S1>S2 and S3>S4 and post the results.

You might also want to resolder these connections.

[selldoor]

Re: Hannspree HF257 2-3 seconds black

You need all 4 bulbs connected otherwise it flags it up as a fault and goes into protection.

Read this guide by retiredcaps - start at post 20 - also part at the end I think about test bulbs.by Budm post 25?

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

S1>S2 = 997 consistent
S3>S4 = between 1004 and 1007

S3>S4 will not fluctuate while being tested but if I test once, wait a min or so, test again it will give a different reading. To me even the 997 sounds kind of high but I could be wrong for those inverter transformers as I do not have any kind of data sheet or any kind of info on them.

[Rtech]

Re: Hannspree HF257 2-3 seconds black

Is C314 slightly bulged,or just the photo makes it look like it is ???

[jetadm123]

Re: Hannspree HF257 2-3 seconds black

Is C314 slightly bulged,or just the photo makes it look like it is ???

Doesn't matter, since he using a stock photo from shopjimmy.

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

Doesn't matter, since he using a stock photo from shopjimmy.

Yes, Sorry about that. I was just using it for a reference as my cheap camera was not getting a good picture at all. I grabbed my mothers camera and got a better picture of my actual board.

[selldoor]

Re: Hannspree HF257 2-3 seconds black

S1>S2 = 997 consistent
S3>S4 = between 1004 and 1007

S3>S4 will not fluctuate while being tested but if I test once, wait a min or so, test again it will give a different reading. To me even the 997 sounds kind of high but I could be wrong for those inverter transformers as I do not have any kind of data sheet or any kind of info on them.

They appear to be ok - we usually reckon they should be within 3% of each other - so you are well within that.

I think budm testlamp is the way to go - It is only a test though just try it for a minute or 2
to see if you can spot a weak bulb ( It may just be the wiring)

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

I think I am going to just re-cap it and see what happens. Time to see if I can track down all the caps locally here.

[selldoor]

Re: Hannspree HF257 2-3 seconds black

Wouldnt bother recapping with local shop radioshack/ frys caps. They are not usually any good. see if you can get them from badcaps.net or digikey -take care with physical size.
use panasonic fm or fr nichicon or rubycon equivalent caps.

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

Well, after further inspection, looks like changing the CCFL tubes will be a piece of cake if I have too. Looks like I just have to pull the metal frame off enough on one end and they slide right out the side. No need to take it to far apart. I hope....

And it looks like ccflwarehouse.com has a relamp kit on sale for $30 right now.

I do wonder if it isnt a CCFL tube though cause I did have the flickering in the bottom left side of the screen and it was flickering for a good 10 seconds before I shut it off and turned it back on and then did it again for a few seconds and turning the monitor off and back on fixed it again for about 10 min then screen went back and thats when all this started.

I turned out the lights in my office and again fired up the monitor with the brightness turned way down and the lower portion of the screen does seem dimmer and there is an ever so faint flickering to it that I didnt notice when the lights were on in the room.

Just thinking out loud again.

Oh yeah, I did order all the caps from digikey. Plus my cousin works there so I was able to get her big discount on my $7 in parts. Saved like .25 cents. Plus living in MN and digikey being about 3 hours away from me, I dont think it will take long to get them.

Really stuck at a crossroads here with the ccfl tubes. Will report back once I recap it.

[budm]

Re: Hannspree HF257 2-3 seconds black

I would pull out the lamp assemblies and inspect real close at the wires attached to the end of the lamps, give it a gentle pull if it will just come off or not.
http://s807.photobucket.com/albums/y...klight%20lamp/

Test lamps:
http://s807.photobucket.com/albums/y...g%20old%20CFL/

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

Well, further inspection I can not just slide the CCFL tubes out so I am going to getting some tubes from a friend to hook up and see if if hooking up a good tube works and if so, then I will know if it is a tube of not. Really leaning that way. I did re-cap the entire board and I dont know if the new caps cause this but now I cant turn the brightness up past 11 or it will go out as where before I swapped the caps I could turn it up to about 17 without it going black. I did triple check all of my solder connections and they are all seem to be good.

The bottom portion of my screen does seem dimmer then the top. I will report back hopefully tomorrow when I get the spare CCFL tubes to test the inverter side of the board. If all test good, I will attempt to change out all 4 CCFL tubes. Hope its not that tough. lol

[selldoor]

Re: Hannspree HF257 2-3 seconds black

I will attempt to change out all 4 CCFL tubes. Hope its not that tough. lol

Try and find some videos on youtube of similar panels

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

Well, I have officially figured it the problem and was really hoping this wasnt it but it is. I hooked up a good pair of ccfl tubes to the board and its been on 100% brightness for about a half hour now. Good news it the power supply/inverter board has all brand new FM series caps on it. I can solder really good and change caps and other stuff like that but this taking the display apart has me a bit nervous but im going to give it a go. Dont really have anything to loose.

Try and find some videos on youtube of similar panels

Finding anything about taking a ccfl tube out doesnt seem to warrent to many search results and the ones I do find all seem to be nothing more then a 15" from a laptop and by the looks of it, they are a different animal then a big 25" LCD monitor.

Im going to set up the GoPro and try and get some video taking this apart.

Would anyone have any idea just how long the tubes are so I could order them before I take this apart. I just would rather this not sit around all week in pieces if it doesnt have too. My luck something would get broken or misplaced.

[retiredcaps]

Re: Hannspree HF257 2-3 seconds black

Would anyone have any idea just how long the tubes are so I could order them before I take this apart.

Members have good feedback for ccflwarehouse.com customer service. You can call them and they will help you find the correct size, etc.

They have a tutorial on how to replace as well.

http://www.ccflwarehouse.com/lasotu.html

You can buy lamps "bare" or pre-harnessed. The latter costs more, but is easier to install.

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

Order a complete retube kit from ccflwarehouse for $30 on sale a few days ago. Hopefully I will get them tomorrow (Saturday) and I can get to work on this.

I have never messed with a monitor before and an acquaintance said he had repaired many of them and had a tester for testing caps inline and first told me things were bad and told me to buy this one power supply/inverer board on ebay so I did, coming from china, waited 5 weeks, got it only to have it be bad (Transformer on PS side), so I did a search leading me here and learning A LOT so I decided to recap my original and still having the 2 seconds then black, a friend had an old busted laptop with a good monitor so I grabbed the old CCFL lamps from that and what do ya know, monitor worked great with them hooked up in place of the ones in the monitor so that was the problem. Had I known this, this would have been fixed weeks ago.

And the gal at ccflwarehouse was super helpful on the phone too.

[budm]

Re: Hannspree HF257 2-3 seconds black

Using test lamp for verification of the inverter circuits when you have 2 seconds to black is the first thing I use, it saves so much time in troubleshooting.

[Hippie459MN]

Re: Hannspree HF257 2-3 seconds black

I know that now. lol I was originally going off what this person said that took a look at the monitor for me when it first started acting up and I didnt have any test lamps at all. I do now though and after doing a lot of reading and working with this, I now now my way around a monitor much better now and will be doing any future testing/repairs myself from the beginning. This has certainly been a great learning experience and even more so once I dig in to getting the lamps out, repaired, and back in.

I cant wait. Sitting here using my spare 15" flatscreen (1024x768 max res) is a nightmare after using my 25" 1080p HD monitor.