Got this nice condition 52" Samsung, fault was backlight starts then shuts off after power up obvious fault in the lower portion of the screen as it was physically dimmer. This set uses two inverters each side of the screen with them tiny buffer transformers and large main one on the Psu. I found that the bottom transformer on both left and right side slave inverters the feedback is high (12v dc on the feedback diode should be 2v any higher causes shutdown) on both them before shutdown meaning a fault in the lowest lamp or one of the transformers that drive it.
I tested both transformers and they tested fine ohms wise, so I tore the panel apart suspecting the lamp to have failed. The lowest lamp had cracked right where it plugs into the connectors on the right hand side complete clean crack as well very odd. Dont understand how as the frame is very sturdy on this and not easily flexible so could of been defect from sale.
I do not have any 52" ccfls in stock so simply I removed the lamp and bridged the outer pins on the buffer transforms on both in inverters for that lamp which dis-enables the protection circuit which keeps the backlight on and working with a missing lamp.
Sealed it up and tbh the panel looks fine no obvious light difference with the bottom lamp missing. I then recapped the Samwha Wb caps on the Psu which are known to fail and resoldered a few things.
Set is working fine looks good as well. Strange this thing is immaculate no dust inside either and it only had 105 hours use and I believe it too. Odd but free fix just need a stand now then will get it up for sale
I tested both transformers and they tested fine ohms wise, so I tore the panel apart suspecting the lamp to have failed. The lowest lamp had cracked right where it plugs into the connectors on the right hand side complete clean crack as well very odd. Dont understand how as the frame is very sturdy on this and not easily flexible so could of been defect from sale.
I do not have any 52" ccfls in stock so simply I removed the lamp and bridged the outer pins on the buffer transforms on both in inverters for that lamp which dis-enables the protection circuit which keeps the backlight on and working with a missing lamp.
Sealed it up and tbh the panel looks fine no obvious light difference with the bottom lamp missing. I then recapped the Samwha Wb caps on the Psu which are known to fail and resoldered a few things.
Set is working fine looks good as well. Strange this thing is immaculate no dust inside either and it only had 105 hours use and I believe it too. Odd but free fix just need a stand now then will get it up for sale
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