Introduction
We are treating a Hisense TV with streaks and double images across the entire screen. At times, the device won't turn on at all or has ghosting or weird stripes. The cause here is either a loose / incorrectly inserted connector or the cheap processing and attachment of the heat sink.
If these causes are not decisive for the error, the television can no longer be saved because the panel or its electronics are damaged.
You should be aware that when testing live 230V AC and 400V DC those are exposed right in front of you. This is limited to the area of the power supply.
You should also be aware that 100 - 450 degrees hot air and workpieces can cause severe burns.
Undivided attention, good light and no distractions are important here.
What you need
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The first step is to remove the back panel. To do this, remove all visible screws, some of which are countersunk, using a Phillips PH1 screwdriver and store carefully.
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Caution: 2 screws are installed in each of the feet from below. Lay the TV flat and unscrew the 2 black screws and pull out the feet underneath. Then you can remove the back panel from below.
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Look around carefully, there is a ribbon cable going from the mainboard to the panel. Note: This TV has NO T Con Board. Carefully release the lock on the panel connector and check the connector for correct seating by re-inserting the cable.
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If the ribbon cable is too tight in step 2, loosen the tape at the crease and push the cable properly into the connector. This may have already fixed the error. Check your work result by plugging in and switching on the TV. It must now display the manufacturer's logo and then "No signal". Caution! 230V live circuit
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If the result is the same as before, look at the mainboard. Disassemble it by first unplugging all the connectors and then unscrewing the 4 screws on each corner. Place the mainboard in a space where you have materials for a BGA rework.
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A large heat sink sits on the mainboard. Dismantle it by squeezing the 2 plastic clamps on the underside and pushing them out. Set the heatsink aside.
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Now remove the thermal paste on the CPU with a little alcohol and a soft kitchen paper. Get a heat-resistant surface, such as a thick metal plate. Place this on the table below the CPU.
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Brush or spread a thick gob of ULF-10 soldering paste / flux around the edge of the CPU. Now turn on your hot air gun and set it to about 100 - 130 degrees Celsius and medium air volume. Now blow on the CPU and the soldering grease until it runs under the CPU. From now on, make sure you don't move the board or leave it lying on an uneven surface!
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If the flux has run well under the CPU everywhere, set the air volume to maximum and the temperature to 450 degrees Celsius. Now heat the entire CPU evenly until the flux bubbles on the sides. Maintain this state for 2-3 minutes.
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Now remove the hot air and let the station cool down. Now wait at least 10 minutes and let the CPU and board cool down. Please do not move or shake! Then reinstall the mainboard with the 4 screws and connect the cables. You don't need the heatsink for a test.
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If the image is perfect again, the BGA rework was successful. If not and the fault pattern is the same as before, it is the panel itself. Then the TV is an economic total loss, since the panel is about the same price as a new TV.
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If the picture is okay again, clean the circuit board thoroughly with spirits (like isopropyl alcohol etc.)and a bristle brush. Also remove the old thermal paste on the heatsink. Both thermal paste and flux are sticky. So use paper towels. Then use fresh paste on the CPU and reinstall the heatsink.
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Follow the steps in reverse order to reassemble your device.
Follow the steps in reverse order to reassemble your device.
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