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Bush LCD32TV005HD PSU blown, no picture after PSU fixed

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wellij81:
Thanks for the info Tony, you've got me worried! I've taken it apart again to have another look. The ident no. on top of the smd diode is KJH. A Google search for 'smd diode kjh' brings up two datasheets, for BAV70 and MMBD7000, both of which say they have kjh as their marking! They are both standard small-signal switching diodes, pretty-much equivalent to 1N4148, although the MMBD7000 is an accurate match for the pinout. The good thing is it isn't a zener, so must be another diode that you've had experience of going on that board? The 100 ohm is circuit ref RD53, but I can't read the diode ref. Unfortunately the manual I downloaded does not include the lcd driver circuit.

Thanks again,

Jonathan

wellij81:
An update for those trying to fix these PSU's. I bought a new controller IC and FET for the 12v side but was concerned when the 12v rail went up to 14.9v and the 24v rail didn't come up when on a dummy load. Spent ages testing the low voltage side, and eventually came to the conclusion that the "12v" side of the PSU is designed to produce 12v in standby and 15v when fully on! The 24v rail was also ok really, just me being cautious. It will not start with a dummy load, but the TV has a longish time-delay on the backlights so it doesn't have to start up under load.
So everything is ok now.
For anyone trying to buy the controller IC (type ICE1QS01), most suppliers seem to charge around £10 for it, but Littlediode do it for £2.85 (+VAT and post, but still much cheaper). It seems like a genuine part and works ok.
I have drawn out the PSU circuit by hand as it isn't in the manual. I may scan it and upload it if anyone is interested.

Jonathan

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