I'm currently trying to fix this LE40C530 TV. The "big picture problem" is that it seems to turn on but there is no picture. The backlights do not fire.
This TV has the inverter power supply on the power supply. This isn't my picture, but it's the same power supply as the board I've got.
The power supply is model BN44-00340B. You can get the circuit diagram from
What I've done is I noticed that the two MOSFETs had blown on the inverter section (they are labelled QI809 and QI825, if you can be bothered to get the circuit diagram). I've replaced them with similar, but not identical, MOSFETs (the ones I bought are https://uk.rs-online.com/web/p/mosfe...hTerm=419-2204, whereas the originals are https://cdn.badcaps-static.com/pdfs/...b42f87e745.pdf)
Having replaced these MOSFETs, it still doesn't work. When you apply power to the set, it sits there for a minute then tries to turn on. At this point the gate pin on the Mosfets show 5V if I put a multimeter on Volt mode, and about 50kHz if I put my multimeter on frequency mode, so I think the MOSFETs are being driven.
This board has two connectors to the inverter board- one with 7 pins for controlling the inverter, and a bigish one that supples the high voltage. On the small one, there are some feedback pins- I never see any voltage on these.
I haven't been able to find out if there is actually any high voltage power going to the inverter board, as it says 800V AC on the power supply board, but my multimeter is only rated for 750V AC, and is fairly Chinese and ropy, so I'm not keen on blowing it up.
All other voltages on the power supply seem OK.
Any tips welcome.
This TV has the inverter power supply on the power supply. This isn't my picture, but it's the same power supply as the board I've got.
The power supply is model BN44-00340B. You can get the circuit diagram from
What I've done is I noticed that the two MOSFETs had blown on the inverter section (they are labelled QI809 and QI825, if you can be bothered to get the circuit diagram). I've replaced them with similar, but not identical, MOSFETs (the ones I bought are https://uk.rs-online.com/web/p/mosfe...hTerm=419-2204, whereas the originals are https://cdn.badcaps-static.com/pdfs/...b42f87e745.pdf)
Having replaced these MOSFETs, it still doesn't work. When you apply power to the set, it sits there for a minute then tries to turn on. At this point the gate pin on the Mosfets show 5V if I put a multimeter on Volt mode, and about 50kHz if I put my multimeter on frequency mode, so I think the MOSFETs are being driven.
This board has two connectors to the inverter board- one with 7 pins for controlling the inverter, and a bigish one that supples the high voltage. On the small one, there are some feedback pins- I never see any voltage on these.
I haven't been able to find out if there is actually any high voltage power going to the inverter board, as it says 800V AC on the power supply board, but my multimeter is only rated for 750V AC, and is fairly Chinese and ropy, so I'm not keen on blowing it up.
All other voltages on the power supply seem OK.
Any tips welcome.
after reading forums like this one we have tried to repair the PSU (BN44-00340b)
this hasnt changed anything atall. The TV still refuses to come on from standby if its been on.
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