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Crumbtrail TV Forums: TV Equipment: LCD TV Forum:
blinking picture Hanns-G LCD TV

 

 


peanut
New User

Apr 30, 2010, 1:58 PM

Post #1 of 16 (4670 views)
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blinking picture Hanns-G LCD TV Can't Post

scuse pun Wink
Hanns-G LCD 26" TV model JT261
last week suddenly switched off and wouldn't turn back on.
Checked caps on PSU board and sure enough most bulged and blown.
I replaced all the caps I had spares for and the set then worked perfectly for a day or so.
Then the picture started to blink to black and back slowly every 2 seconds.
Ordered and replaced remaining caps but now picture blinks continuously and regularly twice a second.

Set functions perfectly otherwise Crazy

Any suggestions welcome . If I don't get this working for the bank holiday we I'm in big trouble with her indoors
[URL=http://s130.photobucket.com/albums/p261/peanutNboo/?action=view&current=tvpsucaps.jpg]



techchris
Veteran

Apr 30, 2010, 4:33 PM

Post #2 of 16 (4664 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

look to see if the back lights are going off and on. if so you have a fault on the inverter board or the screen itself.


peanut
New User

Apr 30, 2010, 7:41 PM

Post #3 of 16 (4660 views)
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Re: [techchris] blinking picture Hanns-G LCD TV [In reply to] Can't Post

thanks Chris I didn't think of that.
When it worked for a few hours after the first repair to the PSU I assumed it was still power related. Its acting like the power supply is collapsing and recovering .

You may have just saved my life Wink


techchris
Veteran

May 1, 2010, 10:20 AM

Post #4 of 16 (4655 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

you may still have a power supply fault if the supply voltages are too low,but you need to get a service manual for that model (unlikely) to check. low or open circuit capacitors can cause this. have you changed all electrolytics on the power board?


peanut
New User

May 1, 2010, 12:00 PM

Post #5 of 16 (4654 views)
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Re: [techchris] blinking picture Hanns-G LCD TV [In reply to] Can't Post

Hi Chris
thank you for the reply. Sorry for delay in respondin.
I have only replaced the caps on the secondary side so far.
last night I changed them all again in case there were some duff ones. I can't find my cap tester anywhere.
All the primary caps are v small,low value low voltage and look fine however I will replace those as well as a precaution.

The thing that keeps me coming back to the PSU is the fact that initially when I first replaced the blown caps in the secondary circuit the tv worked perfectly for a few hours ,then slowly the picture started to blink once every 10 seconds or so increasing over a few hours to twice a second now.

My fear now is that I have inadvertently damaged a sm when I pressed the board rather down hard to remove the heatsink bridges

I read somewhere that someone removed a suspect PSU and attached a temp supply to the tv .?


peanut
New User

May 1, 2010, 8:19 PM

Post #6 of 16 (4649 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

just spotted this sm resistor. It looks a little cooked. Solder is dull and characters on resistor are very difficult to make out. Not burnt just looks like its been very hot . Its immediately below a large diode . If I knew its value i could desolder and test it.



(This post was edited by peanut on May 1, 2010, 8:23 PM)


sebxtreme
New User

Sep 17, 2010, 9:10 PM

Post #7 of 16 (4549 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

is 185 typed in, so h've you solved the prob? because i've the same....

( sorry for my bad english :) i'm a little belgian :) )


peanut
New User

Sep 17, 2010, 9:50 PM

Post #8 of 16 (4547 views)
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Re: [sebxtreme] blinking picture Hanns-G LCD TV [In reply to] Can't Post

Hi Seb.
yes the TV is now fixed. The problem was a faulty power supply . I guessed it was and bought a used PSU off ebay. it worked straightaway.
I still have the faulty PSU but no idea what is wrong with it.
There is another used PSU on ebay at the moment going cheap. Make sure that you visually check it is identical to yours with the same model number. Good luck.


sebxtreme
New User

Sep 17, 2010, 9:51 PM

Post #9 of 16 (4546 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

on ebay nothing at this moment , or do you 've a link?


peanut
New User

Sep 17, 2010, 10:26 PM

Post #10 of 16 (4545 views)
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Re: [sebxtreme] blinking picture Hanns-G LCD TV [In reply to] Can't Post

I just looked and either it was sold or has not been re-listed yet. I'll try to find the seller for you. It was about 50 euros


sebxtreme
New User

Sep 17, 2010, 10:29 PM

Post #11 of 16 (4543 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

is ok, i've find the error :) Q7 and ZD4 need to be replaced
look this :

This one was totally dead with no 5V standby present. The problem was a shorted internal voltage regulator made up of Q7 and ZD4. The Q7 is a SOT23 size device and appears to be too small and over heats in the design. In this case it shorted from the over heating and that caused ZD4 to fail and shut down a 15V bias supply on the power supply board. I replaced Q7 with a 2N4401 to give it more power capability. Any small NPN transistor with a 25V or higher Vce rating will probably work. ZD4 is a 15V zener diode. Note that there appear to be two or three power supplies used in these TVs. This fix may also apply to similar FSP power supplies such as the FSP 228 but that has not been verified.

i hope will help some pple


peanut
New User

Sep 17, 2010, 10:30 PM

Post #12 of 16 (4542 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

the ebay seller's name is 'the 247 enigma' and if you search for this ebay item you will find him.200520495921
you could email him through the item message and ask if he still has the part. You will need the psu board number from your tv


peanut
New User

Sep 17, 2010, 10:33 PM

Post #13 of 16 (4541 views)
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Re: [sebxtreme] blinking picture Hanns-G LCD TV [In reply to] Can't Post

<span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><!--reply--><tr><td width="2%"><hr width="100%" noshade size="1" color="#A1A576"></td><td width="10%" align=center><font size=1 face="Verdana,Arial,Helvetica">In&nbsp;Reply&nbsp;To</font></td><td width="87%"><hr width="100%" noshade color="#A1A576" size=1></td></tr></table></span><div style="margin-left: 30px">is ok, i've find the error :) Q7 and ZD4 need to be replaced <br>look this : <br> <br>This one was totally dead with no 5V standby present. The problem was a shorted internal voltage regulator made up of Q7 and ZD4. The Q7 is a SOT23 size device and appears to be too small and over heats in the design. In this case it shorted from the over heating and that caused ZD4 to fail and shut down a 15V bias supply on the power supply board. I replaced Q7 with a 2N4401 to give it more power capability. Any small NPN transistor with a 25V or higher Vce rating will probably work. ZD4 is a 15V zener diode. Note that there appear to be two or three power supplies used in these TVs. This fix may also apply to similar FSP power supplies such as the FSP 228 but that has not been verified. <br> <br>i hope will help some pple</div><span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><!--/reply--><tr><td><hr width="100%" noshade size=1 color="#A1A576"></td></tr></table></span>

well done seb ! I might take another look at my old PSU board . The first time it failed I replaced all the caps and it worked perfectly for a few hours. Then it started a slow blink which got faster and then picture failed .


sebxtreme
New User

Sep 17, 2010, 10:35 PM

Post #14 of 16 (4538 views)
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Re: [peanut] blinking picture Hanns-G LCD TV [In reply to] Can't Post

me too i've replacing all caps, but nothing live on it....

i hope this will fix :) Q7 is on the repair kit on ebay , i think is one voltage present sensor, if is dont make the signal because burned, no power get out ... same on the mainboard of the xbox 1.6 motherboard ;)


sebxtreme
New User

Sep 18, 2010, 10:11 AM

Post #15 of 16 (4531 views)
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Re: [sebxtreme] blinking picture Hanns-G LCD TV [In reply to] Can't Post

well all work fine, so, ZD4 need to be replaced with a Zener 1,3W 15V and Q7 with any transistor 25V vce or higher
and off course replace all capacity with other same value µf but 35V by 50v as you can because is it majoritary broken
now my lcd screen work fine !
cost : 8 euro.... for fix it !


(This post was edited by sebxtreme on Sep 18, 2010, 3:06 PM)


peanut
New User

Sep 18, 2010, 3:53 PM

Post #16 of 16 (4527 views)
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Re: [sebxtreme] blinking picture Hanns-G LCD TV [In reply to] Can't Post

well done Seb. Thanks for the solution which should be very useful to anyone else with a similar failure

 
 
 


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