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#21 |
Badcaps Veteran
Join Date: Aug 2015
City & State: Cardiff
My Country: Wales
Line Voltage: 230V AC, 50Hz
I'm a: Hobbyist Tech
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![]() You may have more than one CCFL on the brink of failing bearing in mind that they are all the same age.
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#22 |
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Join Date: Apr 2013
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#23 |
Badcaps Veteran
Join Date: Apr 2013
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![]() reviving this thread as a strange fault has occured.
the original fault was one of the ccfl failing ,causing invertor error to shut down backlight .i removed one ccfl tx and fitted link across pin 1 and 4 ,thus removing the faulty ccfl from the cct now for the strange bit , this has worked for weeks no problem , until the pic went off leaving sound and backlights still on green led on . when i switch to sby the led changes to red ,as you would expect but the sound and backlight remain on ! if you unplug mains and try again all is well for 5 minutes ,then the pic is lost ,with sound still on ,and b/l still on . ive checked all supplies in fault condition ,all ok cleaned lvds connections , to be clear the backlight stays on |
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#24 |
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![]() when the picture is lost do you still have voltage at the tcon fuse
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#25 |
Badcaps Veteran
Join Date: Apr 2013
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![]() ive removed the screening plates
but as youve guessed when powered on fault not present ,ive tried heat and freeze ,no luck . i will check t con volts as soon as fault occurs whilst waiting ive been studying cct the psu relay ,is not as straight foreward as you might expect ,when powered off theres a final click a good few seconds after removing power also it has a 6.8 ohm ww across its contacts which puzzles me ? so when its open it still has 6.8 ohms in cct Last edited by jimbofz; 02-21-2021 at 07:55 AM.. |
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#26 |
Badcaps Veteran
Join Date: Feb 2010
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Line Voltage: 120V 60Hz
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![]() The 6.8 Ohm across the relay contact is for limiting inrush current when power is applies to the circuit, the relay is closed to bypass the resistor when TV is turned on.
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Never stop learning Basic LCD TV and Monitor troubleshooting guides. http://www.badcaps.net/forum/showthr...956#post305956 Voltage Regulator (LDO) testing: http://www.badcaps.net/forum/showthr...999#post300999 Inverter testing using old CFL: http://www.badcaps.net/forum/showthr...er+testing+cfl Tear down pictures : Hit the ">" Show Albums and stories" on the left side http://s807.photobucket.com/user/budm/library/ TV Factory reset codes listing: http://www.badcaps.net/forum/showthread.php?t=24809 |
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#27 | |
Badcaps Veteran
Join Date: Apr 2013
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![]() Quote:
perhaps you could explain where the" power on" to psu comes from on this sony ? the main board is labelled AE board on this i cant find power on from micro? above this board is FB2 board these two boards are connected together with multi pin connectors ive studied the cct of both boards,with no luck the sby volts is 5v from psu ,this is fine theres a Pfc detect pin on the psu board, that goes high when psu runs i just want to make sense of it |
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#28 |
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Join Date: Jan 2013
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![]() One good thing about intermittent fault, you can check lots of voltages when it's working and compare them to when it's at fault, check all your solder joints look them over real close and give m the wiggle test, check all the voltage regulators on the mainboard and the test points on the tcon, hopefully you will find something.
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#29 | |
Badcaps Veteran
Join Date: Apr 2013
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![]() Quote:
on the board above the main board marked FB2 (the one inside metal can) you have to remove cam board and the AVC board (tv will work without these 2 boards ) i could get fault to show itself when i heated it up with hairdrier and then with use of freezer spray . so i removed board and found 3 100uf caps faulty with my esr meter . ive replaced them and repeated the test with heat and freeze and tv remainds on. the esr readings of the caps would change with heat 2 were on the print side of board and one on top looks promissing , if it completes the repair i will post pics of the board as theres no component ref numbers |
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#30 |
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Join Date: Apr 2013
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![]() well youve guessed it .
been fine running since my last post re changing caps now it has decided to test my brain futher , i now get 5 blinks at switch on which is usually to do with t con (theres two t con boards just to add to the mix!) fuses on both tcons decided to fail ,no obvious shorts so replaced fuses and still 5 blinks 12v supply on t con ok and nothing getting hot yes i did check all the earth screws in place so im stumped any thaughts ? (apart from scrap it ) |
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#31 |
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Join Date: Apr 2013
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![]() looks like the end of the road for this one,at least i found the fault .
one of the four tcon foils is faulty to remove both ends is major strip down , once done if i flexed gently the tv would trip to 5 blinks . i removed the faulty foil and the contacts had lifted and were shorting . trying to find a replacement is nigh on impossible ive kept some foils from scrap tvs but none are suitable |
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#32 |
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Join Date: Jan 2013
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![]() haven't had to do it myself but have seen some have success by trimming a little off the end of the cables.
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#33 | |
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Join Date: Apr 2013
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![]() Quote:
tried to s/glue with coctail stick and head up magnifier. so annoying as these things probably cost peanuts to manufacture Last edited by jimbofz; 03-02-2021 at 04:24 PM.. |
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#34 |
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![]() well well well managed to find replacement foil ,
bingo rewarded with great pic. it lasted 6 seconds , with scart i/p sound also cut out after 6 seconds now i get 5 blinks removed logic board and t con tested all s mount caps with esr meter measured all vcc supplies for low resistance to deck all ok i think the micro is entering protect mode its nothing to do with backlight ive studied cct ,but cant a find cct for the t con board in the manual t con number:404652hcc 8lv1.8 it has 4 foils to connect to panel not the usual 2 i always like to repair to component level , just as well, as theres no cheap t con boards i suppose what is bothering me the most is the picture is perfect none of the usual symptoms you get with t con faults on the logic board there was two 47 mf caps poor esr which i replaced is there a way to force set on ,ie overide prot cct to allow me to enter s mode to clear the fault? every time it will come on with good pic for 6 seconds any help please |
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#35 |
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![]() Wonder if a firmware update would fix it, didn't see any on the sony UK site tho.
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#36 |
Badcaps Veteran
Join Date: Apr 2013
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![]() yes not avail from sony
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