Have this 40" Jvc Led Tv, rebadged Vestel junk ! Initially I thought we had a bad led with in the Lcd screen as the Tv has sound but no picture, and shining a torch on the screen shows the Lcd glass is working but the backlight isnt. A common fault on Led Tv's is the Leds are wired in series and normally an Led will pop (due to heat) causing the whole lot not to work.
On this one, I had no Led drive voltage coming from Psu with or with out Led connector pluged in so I knew the Psu was at fault. Next I checked 24v rail as that is what drives the Led booster circuit and no 24v rail. So I then checked the 3 diodes in parallel for the 24v rail and one was shorted. Easy fix
Its funny as I had another IPS19 with shorted 24v diode and it would not come out of standby but this does lol. After finding the bad diode by finding the one with lowest ohms across it, I then cut the diode out of cirucit the Tv works but dont run it for long if you do this as it will stress the others due to one not being present. Now just need to order some UF5404 and SB5100 (for 12v rail) its important to replace ALL the output diodes on these supplies when one fails as the others wont be long off blowing up.
Note: You should check the Led booster mosfet if the 24v diodes do short as it could be damaged by this its surface mounted device under the Psu and has a circuit reference of Q501 or if it uses the through hole type Q502 if this is shorted replace it too.
On this one, I had no Led drive voltage coming from Psu with or with out Led connector pluged in so I knew the Psu was at fault. Next I checked 24v rail as that is what drives the Led booster circuit and no 24v rail. So I then checked the 3 diodes in parallel for the 24v rail and one was shorted. Easy fix
Its funny as I had another IPS19 with shorted 24v diode and it would not come out of standby but this does lol. After finding the bad diode by finding the one with lowest ohms across it, I then cut the diode out of cirucit the Tv works but dont run it for long if you do this as it will stress the others due to one not being present. Now just need to order some UF5404 and SB5100 (for 12v rail) its important to replace ALL the output diodes on these supplies when one fails as the others wont be long off blowing up.
Note: You should check the Led booster mosfet if the 24v diodes do short as it could be damaged by this its surface mounted device under the Psu and has a circuit reference of Q501 or if it uses the through hole type Q502 if this is shorted replace it too.
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