Samsung PS-50Q96HD with BN44-00189A Keeps Turning OFF Please HELP!

[Jabboy]

Hi All,

Could someone please help with our faulty TV?
I am new to this forum and wanting to repair my Samsung BN44-00189A so please excuse my noobness.
Our TV works perfect however after it has been on for a few mins it switches itself OFF and makes some clicking sounds then switches back on. It will continue doing this for not sure how long.
I have opened the back of the TV and see no bad Capacitors etc.
I have learned good soldering skills and basic Multimemter usage.
I really hope someone with the knowhow can guide me?
Any help would be much appreciated.
Regards

[t1412]

hi mate, i had a fault like this before it turned out to be a dry joint on one of the transistors, qx801, wot power supply is yours. the one i repaired was bn44-00189. hope it helps

regards
shaun    

[Jabboy]

Hi Shaun,

Thak you for replying..... my PSU is quoted in the subject and it is: BN44-00189A or PSPH531801A.
I have taken the old Soldering off the QX801/2 and chaged almost all Caps except the few Larger ones.
With that said the issue still remains.
I am not sure what else it can be as there are no visible Burns, Bad joints or broken bridges etc :S.
Can anyone Please Help???

[t1412]

sorry m8 got to get my eyes checked, have you tested the larger transistors on the same heatsink as qx801, wots the va/vs voltages, i think there is a repair kit for this board, ohms supplies stock them!! 

shaun   

[Jabboy]

Its Great my bad I didnt put PSU in subject but just the name.
I am not sure what you mean by va/vs voltages???
How do i test these and what do i look for? I have a basic Digital meter.
On the green side, I checked the QX801/1 QS801 etc and the QX801 shows 12 and 12 while the QS's are around 54? if thats any good?
as for the Large Transistor, I have not paid any attention to it, what do i look for? there are no burns etc
Thanks

[t1412]

here are some of the pictures of the va/vs voltage test points, you will have to turn the tv on so beware don't get shocked and try not to catch any other components with the meter probes, put the black probe on a good ground like a metal part of chassis, now to touch the long pin with red probe va should read 207v and the vs should read 63v if you have to adjust the setting turn the little screw next to the long pin good luck,   

shaun            

[Jabboy]

Ah, Interesting, Never knew about these.
I will have a go later on todaya nd update you.
a little scared of Electricity especially 270V :O lol.
I will try and be brave. Many thanks.

[Jabboy]

Just tested the VS and VA.

The result was that the VS is 208.4 and VA is 65.
Now I am not sure if the slight diffirence is due to the cheap Vichy Multimeter I use or would you say it needs adjusting? I can get my Fluke out now and update u also.

Kind regards

[Jabboy]

UPDATE!!

Fluke shows 208.3 and 65. Hope this helps.
These have now been adjusted to 207.3 and 63.3.
I will test it now and see if it HELPS.

Nope. Still turns off after about 2 minuts and clicks. Really ODD.
Could this be Y-SUS or X-ZUS causing the PSU to fail? any idea please?
Regards

[t1412]

it's possible unplug it, see if you get a blank screen also unplug the z board test the fuses on  both the ysus and z boards and the soldered fuse as well

shaun 

[Jabboy]

Will disconnect both and let it run.

Thanks for your help. 

[Jabboy]

Tried the above and Unfortunately it still turns off :(. Faulth is definately PSU now.

[t1412]

where abouts are you located i have a working board


shaun
 

[Jabboy]

Oh Really???

I am in South Yorkshire, Barnsley.

[jurq]

From my experience this PSU has same old story 'Dry joints', most of the faults in this PSU comes from soldering quality (Pb Free ). Even if the Y-Buffers, Y_Sus is faulty you must do dry joints on PSU!!