Picked up this Samsung LE32A457 as it would intermittently fail to power on. Sometimes it would also cut out while running or the backlight would flicker but it would continue working. Or it would restart. When working, everything was OK with picture and sound. Checked PS ON/OFF signal and it was functioning as expected (on this set it's active HIGH) so it must be the power board at fault.
I replaced the common CM808 capacitor, no dice.
I found that by tapping around the power board it would cut out, so I reflowed a few suspect solder joints. Still no luck, still cut out when tapped.
When it was struggling to power up, Vcc for main controller was ~9V, operational was 15V. So I focused on QB802. Input of QB802 was OK, at ~23V regardless of fault.
Then I noticed QB802 with some glue on it, which had dried out, touching some of the pins. I cleaned this off and it's not cut out once... Anyone found this glue to be intermittent? I'm thinking that some was touching the pins partially, vibration was completing the circuit causing issues. But I've never encountered this before.
Been working for nearly an hour with neigh but a flicker from the screen.
I replaced the common CM808 capacitor, no dice.
I found that by tapping around the power board it would cut out, so I reflowed a few suspect solder joints. Still no luck, still cut out when tapped.
When it was struggling to power up, Vcc for main controller was ~9V, operational was 15V. So I focused on QB802. Input of QB802 was OK, at ~23V regardless of fault.
Then I noticed QB802 with some glue on it, which had dried out, touching some of the pins. I cleaned this off and it's not cut out once... Anyone found this glue to be intermittent? I'm thinking that some was touching the pins partially, vibration was completing the circuit causing issues. But I've never encountered this before.
Been working for nearly an hour with neigh but a flicker from the screen.
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